RepRapPro Mono Mendel Construction Manual

REPRAP PRO

Mono Mendel October 2013 to May 2014

Haynes Construction and Repair Manual

Includes Construction, Maintenance and Troubleshooting

RepRapPro Construction Manual Jonathan Beeby Models covered RepRapPro Mono Mendel

Š Beeby Publishing 2014

Printed in the UK

A book in the Haynes Service and Repair Manual Series

Beeby Publishing Sandyford, Newcastle Upon Tyne NE2 1DN, England

All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage or retrieval system, without permission in writing from the copyright holder.

ISBN 1 84425 168 3 British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library.

Construction Frame assembly Y-axis assembly

X-axis assembly

Contents 1 7

11

Z - axis assembly

15

Extruder drive assembly

23

Heatbed assembly Hot end assembly

19 27

Wiring 33 Power supply

41

Commissioning 45 Printing 51

Introduction & Tool list Introdution

General notes

Tool list

These pages are the complete instructions for building, commissioning and using the RepRapPro Ltd Mono Mendel. They are mirrored on the RepRap Wiki here: http://reprap.org/wiki/RepRapPro_Tricolour

Give yourself plenty of space and ensure your work area is clean. Dust and dirt are a 3D printer’s worst enemy. All printed parts have been printed on various RepRap machines from suppliers within the RepRap community.

Despite the fact that these machines are highly tuned RepRap 3D printers, some holes and features may need a little fettling to get the best performance from your machine. This is especially true for the Igus bushings used for the Z axis. There is a video how-to on fettling 3D printed parts on Vimeo.

Before you start the build, please ensure you have all the components as listed on the packing list included in the kit. If anything is missing, please contact us via email: Reprappro-em.png BEFORE YOU ATTEMPT TO ASSEMBLE ANY PART OF THE RepRapPro Mendel 3D PRINTER, PLEASE READ THESE BUILD INSTRUCTIONS FULLY AND ENSURE YOU UNDERSTAND THEM. Although all parts are covered by warranty, this will be invalidated by your not following these build instructions. If anything is unclear please get in contact with support prior to assembly in order to ensure no damage caused to your machine.

The RepRapPro Mendel is a robust RepRap machine once assembled; however it does require a certain amount of care during assembly. If in doubt, force is usually not the answer!

Mechanical

Like all RepRap machines, RepRapPro Mendels are fully open-source. They are licenced under the GPL. All the design files and software are available from the RepRapPro Ltd Github repository. If you want to print the plastic parts for a RepRapPro Mendel, see the appropriate section of that repository.

RepRapPro Tricolour Mendel is based on the previous RepRapPro Mono Mendel with many alterations and additions. It was designed in order to further simplify assembly and to increase build volume when using multiple extruders.

These instructions document the assembly of a single material/colour “Mono” Mendel. The extra Tricolour instructions follow the Mono instructions.

It is recommended that Tricolour machines are initially assembled as Mono Mendels, before being extended to Tricolour machines after commissioning, and you have gained some experience using the Mono. You are building a complex machine - the skills required and the rate at which you learn mean that troubleshooting when you have built it all at once is much more challenging.

Tools required for the mechanical build of the RepRapPro Mendel 3D printer: • Drill bits including 2mm, 3mm, 6mm and 8mm • Precision screwdriver set • A set of metric allen keys including: • 2mm (M2.5 size) • 2.5mm (M3 size) • 4mm (M5 size) • 13mm spanner (M8 nut) • 8mm spanner (M5 nut) • 5.5mm spanner (M3 nut) • 5mm spanner (M2.5 nut) • 15cm adjustable spanner • Half round needle file • Craft knife • Fine tweezers • 300mm rule • Vernier or digital calipers • Square • Fine nosed pliers • Pliers • Side cutters • A small amount of superglue (for securing the hobbed insert) Electrical Tools required for the electrical build of the RepRapPro Mendel 3D printer: • Digital Multimeter • A fine-tipped soldering iron • Precision screwdrivers • Solder • Hair dryer or cigarette lighter (or other heat source for heating heatshrink wire sleeving; the barrel of a soldering iron works OK) • Wire strippers/cutters • Crimping tool (very useful, but not absolutely necessary; you can do it by hand) • EITHER Ratchet crimp tool Such as this one, which we use • OR Molex crimp tool (such as the 63811-1000, you may also want the extraction tool 11-03-0044, Molexkits. com) • Scissors

Chapter 1: Frame assembly Contents Goal 1 Tools 1 Frame triangles 2 Cross bars 3

Put them all together Z-motor mounts, diagonal, and power connector Smooth Rods Aligning the frame

Goal

Tools M8 (13mm) spanner Adjustable spanner 300mm Rule

Lasercut MDF Measuring template (supplied with kit) (optional) Spirit level, cotton and Blu-tack

3 4 5 5

2 | Frame assembly Frame Assembly

Tools • M8 (13mm) spanner • Adjustable spanner • 300mm Rule • Lasercut MDF Measuring template (supplied with kit) • Spirit level, cotton and Blu-tack (optional)

Frame triangles Items Quantity 370mm M8 rods . . . . . . . . . . . . . . . . . . . . . . 6 Printed frame vertex with foot . . . . . . . . . . . 4 Printed frame vertex . . . . . . . . . . . . . . . . . . . 2 Printed U clips . . . . . . . . . . . . . . . . . . . . . . . 2 M8 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 M8 lock washers . . . . . . . . . . . . . . . . . . . . . 28 1.1 Required components Note that there are three types of printed U clips in your kit (1.2)

Split the components into two equal sets.

The ones on the left are the frame clips, the ones in the middle are the Z-drive flexible coupling clips, and the ones on the right are the printed-circuit-board clips. For this step you want the ones on the left.

The footed frame vertices are not all the same; there are two pairs. For each frame triangle, use a pair of vertices with feet that point in different directions. (1.3) Also, make sure you slide a belt clamp along the bottom M8 threaded bars between the frame vertices with feet, with a lock washer and nut either side. The other nuts should also all have lock washers under them. Loosely screw together each frame triangle.

Make the gap between the frame vertices measured face to face next to where the nuts and washers tighten about 290 mm using the frame measurement jig. (1.6)

1.2 Different U clips in kit

1.3 Footed vertices in pairs

1.4 Single frame triangle

1.5 Both frame triangles completed

1.6 Frame measurement jig

Frame assembly | 3

1.7 Required components

1.8 Assembled bars

Cross bars

Assemble the bars as shown in (1.8)

Items Quantity 330mm M8 rods . . . . . . . . . . . . . . . . . . . . . . 4 470mm M8 rods . . . . . . . . . . . . . . . . . . . . . . 2 Printed U clips . . . . . . . . . . . . . . . . . . . . . . . 4 8mm bearings . . . . . . . . . . . . . . . . . . . . . . . 2 M8 lock washers . . . . . . . . . . . . . . . . . . . . . 24 M8 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

NOTE: the 3rd and 5th bars (the ones with 608 bearings) are not quite the same! One does not have washers around the bearing.

Put them all together Items Quantity M8 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 M8 lock washers . . . . . . . . . . . . . . . . . . . . . 8

From top to bottom and left to right the sequences are: 1 Lock washer, nut, nut, lock washer 2 Lock washer, nut, nut, lock washer 3 Lock washer, nut, nut, lock washer, U Clamp, lock washer, nut, nut, lock washer, bearing, lock washer, nut, nut lock washer, U clamp, lock washer, nut, nut, lock washer 4 Lock washer, nut, nut, lock washer, lock washer,nut, nut, lock washer 5 Lock washer, nut, nut, lock washer, U clamp, lock washer, nut, nut, bearing, nut, nut, lock washer, U clamp, lock washer, nut, nut, lock washer 6 Lock washer, nut, nut, lock washer.

Slide all the cross bars into one of the triangles (1.11) and secure lightly with a locking washer and nut on each rod end.

Next slide the second triangle onto the other end of the cross bars; use a locking washer and a nut on each rod end. The holes in the feet should line up to form an X as shown in red below.

Using the numbers of the rods from Step 2: At the top attach the two long Rods: 1 and 2.

Back top: Rod 3 Back bottom: Rod 4 Front top: Rod 5 Front bottom: Rod 6 Now go round the frame tightening everything up using two spanners. Tighten the triangles first, then the six bars in the x direction.

Use the template to get the measurements right.

Make the gap between the faces of the vertices on the triangles 290mm. Make the gap in the X direction between the faces of the vertices 273mm, along the length of each crossbar.

Get the two top rods even, with an equal amount projecting each side, then move the back one 5mm to the right and the front one 5mm to the left.

Try to get the measurements accurate. But it is more important to get the lengths equal than to get them precise.

1.9 Caption

1.10 Frame measurement jig

290mm 273mm

1.11 Square base

1.12 Measurements

4 | Frame assembly Z-motor mounts, diagonal, and power connector Items Quantity 470mm M8 rods . . . . . . . . . . . . . . . . . . . . . . 2 Printed Z motor holders . . . . . . . . . . . . . . . . 2 Printed U clips . . . . . . . . . . . . . . . . . . . . . . . 2 M8 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 M8 lock washers . . . . . . . . . . . . . . . . . . . . . 14 M8 washers . . . . . . . . . . . . . . . . . . . . . . . . . 10 XLR panel plug . . . . . . . . . . . . . . . . . . . . . . . 1 20mm M3 caps . . . . . . . . . . . . . . . . . . . . . . . . 2 M3 washers . . . . . . . . . . . . . . . . . . . . . . . . . 2 M3 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.14 Required components Put the two U clips on the bottom rods of the frame triangles roughly in the middle of their bars. Using a 470mm rod, thread it through the two U clips, with a nut and lock washer each side. You may have to twist the rod to get it through the U clips, using its thread to move it - it can be quite a snug fit. Secure the rod to the frame with another lock washer and nut on the outside of each U clip.

Use nuts and lock washers to put two more U clips on its ends for the Z smooth rods (1.15).

Leave all these loose.

1.15 Lower rod composition

The order of parts on the lower rod should be: nut, lock washer, U clip (for z smooth rod), lock washer, nut, nut, lock washer, U clip (frame), lock washer, nut - (gap between frame triangles) - nut, lock washer, U clip (frame), lock washer, nut, nut, lock washer, U clip (for z smooth rod), lock washer, nut Next thread the base diagonal rod through two of the four feet. Put nuts and lock washers on it both inside and outside each foot, but leave them lose. (1.22) Put eight smooth washers on the top bars, with two on either side of each rod then put the Z motor mounts on.

1.16 Top bar composition

Secure them with two nuts each, with one smooth washer and one lock washer. The smooth washer goes on the clamp that will hold the Z rods. Tighten the other nuts against their lock washers, but leave the Z-rod-clamp nuts lose.

1.17 Z rod clamp

1.18 XLR plug

Fit the XLR plug to the frame vertex at the rear right of the machine with the socked facing outwards, i.e. this is the side with the nuts on the bottom bar and on the foot with the diagonal cross brace, using the M3 screws, nuts and washers. The washers go under the nuts. Fit the plug so that the triangle formed by its three pins points upwards. (1.18)

Frame assembly | 5 Smooth Rods Items Quantity 400mm smooth rods (Y) . . . . . . . . . . . . . . . . 2 350mm smooth rods (Z) . . . . . . . . . . . . . . . . 2 Check that the linear bearings slide smoothly on each of the smooth rods. The linear bearings may need a little extra oil, and the smooth rod may need cleaning, for smooth running. The quick way to clean the smooth rod is to put it in an electric drill, then use wire wool or a kitchen scourer on it while the drill turns the rod. Be careful though!

Slide the Y rods through the U clamps. Adjust the U clamps on the left-hand Y rod so that there is a gap of 22mm between their nuts and the nuts on the left frame triangle. Adjust the right-hand Y rod U clamps so there is 175mm between the rods. Lightly tighten the clamps on the rods.

Now slide the two Z smooth rods into place.

Do not over-tighten the clamping nuts on the Z motor mounts. The rods need to be held firm, that is all.

1.19 Square Z rods horizontal

Aligning the frame Place the frame on a flat surface. Wooden furniture, by and large, is not flat. But thick kitchen worktops are very flat.

Frame alignment order: 1. Check all triangle sides are equal 2. Check cross bars (between vertices of triangles) are all equal 3. Adjust base diagonal to square the base; you should be able to measure across the

1.21 Completed frame

1.20 Square Z rods vertical corners of the base (upside down is easiest) the red lines shown in the image here: 4. If the frame doesn’t sit flat on the table (assuming a flat table) once you’ve done this, press the frame on the corners that are high, so the base square does sit flat.

5. Use the supplied glass to check that the Y axis smooth rods are level with each other.

The rods need to be level, or the heated bed will not move in one plane only; one side will rise and fall as it move back and forth on the Y axis. Place the glass on the rods, and see if the glass rocks. Use a piece of paper on each side, and at each end, to check there is no gap between rod and glass. If the rods are not level, check your table is flat, that nothing is caught under the footed vertices, and that the smooth rod bar clamps are evenly clamped.

You will have to remove the rods to fit the Y axis and bed, but this test will check that your construction is correct and the frame is square.

If you can’t get the rods quite level, you may need to place a shim under one foot, like a folded piece of paper, to get the bed perfectly level. Leave doing this until later.

6. Square the Z rods front/back. Tie a piece of string quite tightly around the base of both Z rods, and measure along the triangle bottom rod on each side to get the rods central.

Equalise the length by moving the frame clip along the triangle bottom rod. (1.19) 7. Square the Z rods left/right, using a set square. (you can put the glass on the Y rods diagonally to help) (1.20) 8. Measure the distance between the Z rods top and bottom to check they are parallel You can now tighten the M8 nuts along the bottom cross bar. You will have to remove the Z rods to fit the X axis; only undo the outer nut on each side, you should then be able to put them back in without moving the frame too much, though you may need to check it again after fitting the X axis.

You can revisit this checklist at any point during building and running your machine, to check your frame is still square.

You will now have an assembled RepRapPro Mendel frame (though the smooth Y rods and the bearings will still be loose) (1.21)

6 | Frame assembly

Chapter 2: Y-axis assembly Contents Goal 7 Tools 7 Y motor and mount 8 Motor bracket assembly 8

Y frog assembly Mounting the Y frog Fitting the Y belt Y endstop

Goal

Tools M8 (13mm) spanner Adjustable spanner M3 Allen key

M3 spanner / nut runner Long-nosed pliers Side cutters

9 9 10 10

8 | Y -axis assembly

2.1 Required components

2.1 Motor w/ pulley

2.2 Motor mount assembly

2.3 Motor mount assembly

2.4 Y motor mounted

2.5 Y motor mounted

Y motor and mount

Motor bracket assembly

Items Quantity Lasercut Y motor mounts . . . . . . . . . . . . . . . 2 Printed closed spacer . . . . . . . . . . . . . . . . . . 1 MXL pulley . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Printed open spacer . . . . . . . . . . . . . . . . . . . 1 Nema 17 stepper motor . . . . . . . . . . . . . . . . 1 Printed belt guide . . . . . . . . . . . . . . . . . . . . . 2 M3 washer . . . . . . . . . . . . . . . . . . . . . . . . . . 6 M3 x 25mm cap screws . . . . . . . . . . . . . . . . 2 623 bearings . . . . . . . . . . . . . . . . . . . . . . . . 3

Take one of the printed MXL pulleys and push it onto the motor shaft, taking care to note its orientation.

The bore of the pulley is D shaped to match the motor shaft. One end of the pulley bore is round to make it easier to slide it onto the motor shaft. The pulley should therefore be pushed onto the motor shaft, round end first.

It should be a tight fit, and you may have to tap it into place. Use a soft hammer, or a wood block. If you place a tube against the pulley that will fit over the motor shaft, you can tap the end of the tube to place the pulley. Support the motor shaft, not the motor body, from the other end as you tap. You can secure it with a drop of superglue if you like (make sure the shaft is completely free of grease). Take care that no glue gets near the shaft’s entry to the motor.

Leave a gap of about a millimetre between the pulley and the motor body, so the pulley can turn freely, and not rub against the motor body.

(2.1) Now begin assembling the Y motor bracket.

Insert one of the M3 cap screws and a washer through the slots in the motor mount closest to the semi-circular cut out. Insert this through two washers, then three 623 bearings and another two washers, and finally through the

corresponding slot of the second motor mount.

The order is M3 cap screw, washer, laser cut mount, 2 x washer, 3 x 623 bearing, 2 x washer, laser cut mount.

Repeat this for the remaining slot. However the middle bearing assembly and washers are replaced by the closed spacer. Now the order is M3 cap screw, washer, laser cut y motor mount, closed spacer, laser cut y motor mount.

Finally attach this assembly to the Nema 17 motors using the cap screws. The wire orientation should be facing the circular cut out of Y motor mount. (2.2 & 2.3) Next take this assembly and attach it to the frame at the rear of the machine. The motor mount assembly should be placed around the bearing at the back of the machine with a belt guide placed between the bearing and the motor mount. The order for the top bar is, M8 Nut, lock washer, Laser cut motor mount, belt guide (features facing towards the belt), bearing, belt guide (features facing towards the belt). laser cut motor mount, lock washer, nut.

The open spacer should be clamped between the Y motor mount on the bottom (2.4 & 2.5).

Y - axis assembly | 9 Y frog assembly Items Quantity Lasercut frog . . . . . . . . . . . . . . . . . . . . . . . . 1 LM8UU linear bearings . . . . . . . . . . . . . . . . 3 Printed belt guide . . . . . . . . . . . . . . . . . . . . . 2 Printed bearing holders . . . . . . . . . . . . . . . . 3 Printed belt clamps . . . . . . . . . . . . . . . . . . . 2 M3 x 25mm cap screws . . . . . . . . . . . . . . . . 10 M3 Nylock nut . . . . . . . . . . . . . . . . . . . . . . . 10 M3 washer . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Attach the bearing holders to the lasercut part with 25mm cap screws, nylock nuts and washers (2 washers per screw, one on each side). You may find that there is a small bridge of printed material that needs to be drilled out to connect the hexagonal hole with the circle hole on the opposite side of the bearing holder.

If this is the case use a 5mm drill bit and clean the part before attaching it to the Y frog. Don’t tighten the nuts. Push the bearings into the bearing holders from the side as shown on the right. Do not try to clip them in from on top.

The bearings should be a snug fit. But if they are a bit lose, simply wrap a little Kapton tape two or three times round the lose bearing. Get it flat without wrinkles or bubbles. (2.7) Next attach the two belt clamps to the frog on the opposite side compared to the bearing mounts. Use the remaining capscrews, with two washers and a nylock nut on each. At this stage these should remain loose. (2.8 & 2.9)

2.6 Required components

Mounting the Y frog Now loosen all of the Y bar clamps so that you are able to slide the bars out, then slide the Y Frog assembly onto the bars with the bearings facing downwards, and the side with two bearings towards the left of your machine with the motor at the back. Leave the bar clamps loose for the moment.

Using your measurement jig, tighten and adjust the U clamps on the left-hand Y rod so that their nuts are 22mm from the nuts on the left frame triangle, and then adjust the right-hand Y rod U clamps so there is 175mm between the rods.

It is very important that these measurements are precise.

Next you need to ensure that the motor and idler bearings are aligned with the Y frog.

Begin my moving the Y frog so that it is nearest the motor, loosen the M8 Nuts that secure the motor bracket, and ensure that the large bearing is directly opposite the belt clamps on the frog and re-tighten the M8 nuts. (2.10) Repeat this process for the Y idler bearing, at this point place the two belt guides either side of the bearing to be clamped by the nuts.

Now run the axis back and forth a few times, and go around and tighten the nuts that secure the bearing mounts.

2.7 Frog assembly

2.8 Frog assembly

2.9 Frog assembly

2.10 Y frog alignment

10 | Y -axis assembly Fitting the Y belt

2.10 Timing belt

2.11 Required components

2.12 Mounted endstop

2.13 Mounted endstop

Next fit the belt. Don’t cut it until you have fitted it, you need the rest for the X axis, and you don’t want to cut it too short! Make sure the Y motor cap screws are loose, and the motor is as close to the frame as possible - you tension the belt by pulling the motor away from the frame once the belt is fitted.

Loosen the belt clamp on the motor side slightly and insert the belt under the clamp, with the teeth facing upwards, from the centre of the frog towards the motor. You don’t need much spare, just to the edge of the frog is fine.

Loop the belt up over the top of the clamp, over the bearing nearest the motor, around the pulley, over the top of the small idler bearings integrated into the clamp (so that more of the pulley is gripping the belt), and around the Y idler bearing. Put the belt over the second bearing clamp, and tuck it back underneath belt. So the belt should loop over the top of each clamp and back underneath. Pull the belt through so there isn’t too much slack. Tighten the belt clamps. Cut the belt so it is flush with the edge of the frog.

The belt tension should be fairly loose at this stage. You can slide the Y motor back and forth to adjust the tension, lock it in place by tightening the Y motor cap screws. Adjust the tension such that the belt is tight, but not so tight that the axis begins to bind.

Y endstop Items Quantity Printed endstop holder . . . . . . . . . . . . . . . . . 1 Microswitch . . . . . . . . . . . . . . . . . . . . . . . . . 1 M2.5 x 16mm cap screws . . . . . . . . . . . . . . 2 M2.5 washers . . . . . . . . . . . . . . . . . . . . . . . . 4 M2.5 Nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 M3 x 20mm cap screws . . . . . . . . . . . . . . . . 1 M3 nut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 M3 Washer . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2.14 Completed Y axis assembly

Use the M2.5 washers, nuts and cap screws to clamp the endstop to the endstop holder.

You’ll notice that the endstop holder has four holes. The endstop should be clamped to the outermost two holes, with the nuts on the large flat side and the lever facing towards bar clamp.

Use the remaining M3 fasteners to attach the bar clamp to the back of Y smooth rod that only has one bearing on the Y motor side near the XLR socket. The endstop should be positioned such that it is hit just before the frog hits the the Y bar clamp and the Y motor bracket.

If your endstop holder has a nut trap on the wrong side (the short leg), ignore it; if you put the M3x20mm through from the back, it will protrude too much and hit the bed. Put the screw cap into the nut trap, without a washer.

(2.12 & 2.13) At this stage your machine should look like the illustration (2.14)

Chapter 3: X-axis assembly Contents Goal 11 Tools 11 X end assembly 12 X motor assembly 13

Goal

Tools M3 Allen key Long-nosed pliers Tweezers

X endstop adjuster X carriage assembly X endstop

13 13 14

12 | X - axis assembly X end assembly Items Quantity 428mm smooth X rods . . . . . . . . . . . . . . . . . 2 Printed X motor bracket . . . . . . . . . . . . . . . . 1 Printed X idler bracket . . . . . . . . . . . . . . . . . 1 Printed X idler cover . . . . . . . . . . . . . . . . . . . 1 623 bearing (10mm diameter) . . . . . . . . . . . 1 M3 washers . . . . . . . . . . . . . . . . . . . . . . . . . 2 M3 x 25mm cap screws . . . . . . . . . . . . . . . . 2 M3 x 20mm cap screws . . . . . . . . . . . . . . . . 1 LM8UU linear bearings . . . . . . . . . . . . . . . . . 3 M3 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Begin by assembling the X Idler Bracket. Take one M3x20 cap screw and a corresponding washer and insert it through the hole in the centre of the part as shown (3.2). Then insert this assembly through the 623 idler bearing, through the cover and secure with a M3 nut and washer. (3.3)

3.1 Required components

Next insert two M3 nuts into the slots on the back of the idler bracket (3.4). These are intentionally a tight fit, so you may need to use a long-nosed pliers in order to grip them. The nuts should go in sufficiently far that the holes of the M3 nuts line up with the small holes in the end of the idler bracket. Insert 2 M3x25 cap screws through each of these two holes, and into the nut.

Next begin to assemble the axis. Take the 428mm smooth rods and insert these into the large holes in the end of the X idler bracket.

Then proceed to slide the linear bearings onto the smooth rods. Note the orientation of the bearings, when looking at the top/complex side of the idler bracket, two bearings go on the top bar with the one remaining bearing on the bottom bar. (3.5)

Ensure the rods are completely inserted into the X idler bracket, then insert the free end of the rods into the X motor bracket. (3.6)

3.2 X Idler bracket assembly

3.3 X Idler bracket assembly

3.4 Back of idler bracket

3.5 Smooth bar and bearings into idler bracket

3.6 Insertion of X motor bracket

X - axis assembly | 13

3.7 Required components

3.8 MXL pulley on motor

3.9 Motor secured to bracket

X motor assembly

X endstop adjuster

X carriage assembly

Items Quantity Nema 17 stepper motor . . . . . . . . . . . . . . . . 1 MXL printed pulley . . . . . . . . . . . . . . . . . . . . 1 M3 washer . . . . . . . . . . . . . . . . . . . . . . . . . . 2 M3 x 16mm cap screw . . . . . . . . . . . . . . . . . 2

Items Quantity M3 nut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 15 x 4mm spring . . . . . . . . . . . . . . . . . . . . . . 1 M3 washer . . . . . . . . . . . . . . . . . . . . . . . . . . 2 M3 x 25mm cap screw . . . . . . . . . . . . . . . . . 2

Items Quantity Printed X carriage . . . . . . . . . . . . . . . . . . . . 1 MXL timing belt . . . . . . . . . . . . . . . . . . . . . . 1m

Take a printed MXL pulley and push it onto the motor shaft, taking care to note its orientation.

Leave a gap of about a millimetre between the pulley and the motor body, so the pulley can turn freely, and not rub against the motor body.

(3.8).

Use the two M3 cap screws and corresponding washers to secure the motor to the X motor bracket (3.9). Note the orientation of the motor wire relative to the bracket.

In this step we assemble a Z endstop adjuster.

This is used to ensure that the extruder nozzle is just the right height above the bed. Take the M3 cap screw and a washer and insert them into the spring with a washer on the opposite site. This assembly inserts into the small hole on the X motor mount by the bottom clip bearing holder. Place the nut into the nut trap on the opposite side of the hole and tighten to take up the slack as shown. (3.11)

Firstly push the linear bearings from the sides on the X axis into their slots on the X carriage.

The bearing should be a snug fit. But if they are a little lose, simply wrap a layer or two of Kapton tape round them.

Cut off a small length of belt approximately 80mm long (the width of the X carriage), and press this into the slot of the carriage with the teeth facing upwards. This fit is deliberately tight, the belt should be pushed to the very back of the slot. The remaining belt is fitted after the axis has been fitted to your machine.

(3.13)

3.10 Required components

3.11 X endstop adjuster assembly

3.12 Required components

3.13 Carriage assembly

14 | X - axis assembly X endstop Items Quantity Microswitch . . . . . . . . . . . . . . . . . . . . . . . . . 1 M2.5 x 16mm cap screw . . . . . . . . . . . . . . . 1 M2.5 washer . . . . . . . . . . . . . . . . . . . . . . . . 1 Insert the M2.5 capscrew and washer into the hole nearest the button of the microswitch with the lever facing upwards. This then screws directly into the small back of the X motor bracket next to the motor as shown. (3.15)

3.14 Required components

3.15 X endstop mounted

Chapter 4: Z - axis assembly Contents Goal 15 Tools 15 Z coupling 16

Goal

Tools M3 allen key Long-nosed pliers Tweezers

Z drive Z endstop X belt

16 17 17

16 | Frame Assembly

4.1 Required components

4.4 Required components

Z coupling

Z drive

Items Quantity Nema 17 motor . . . . . . . . . . . . . . . . . . . . . . 2 Printed coupling . . . . . . . . . . . . . . . . . . . . . . 4 30mm 5mm diameter tubing . . . . . . . . . . . . 2 M3 washer . . . . . . . . . . . . . . . . . . . . . . . . . . 8 M3 nut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 M3 x 20mm cap screws . . . . . . . . . . . . . . . . 4 M3 x 10mm cap screws . . . . . . . . . . . . . . . . 4

Items Quantity M5 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 15 x 5mm spring . . . . . . . . . . . . . . . . . . . . . . 2 8mm Igus clip bushing . . . . . . . . . . . . . . . . . 4 215mm M5 studding . . . . . . . . . . . . . . . . . . . 2

Begin by loosening the Z smooth rod clamp at the bottom and the Z motor mount at the top on one side, just enough so that you can slide the smooth rod out. Do not undo the clamps completely, as your machine has already been squared and will require realignment other wise. Remove one smooth rod, which you will use to test the X axis.

Start by fitting the couplings to the Z Motor.

Inserting half of the tubing over the motor shaft.

Next take one of the printed couplings and clip it over the motor side of the tubing as shown.

Ensure that the gap in the coupling is aligned with the flat of the motor shaft. Then insert one of the M3 X 20mm cap screws and a washer into the hole in the coupling, and secure with a nut on the other side. Repeat this setup on the free side of the tubing; however leave the clamps on the free side loose. (4.2) Repeat this setup for the second Nema 17, and mount each of these motors to the Z motor mounts at the top of the frame using the 2x M3x10mm cap screws and washers on each.

(4.3)

4.2 Z coupling

4.3 Mounted Z motors

Z - axis assembly | 17

4.5 Clip bushings

4.6 X bracket trap

4.7 M5 rods gap

Insert the clip bushings into the X ends. You can curl them up so their ends overlap to insert them. Check their internal diameter by running the smooth rod you removed from the Z axis through them. The rod should be held with no free play, but move smoothly with little force.

(4.5) Next insert a spring and an M5 nut into the slots within the X ends. The nut should be placed at the top of the trap (the side with two linear bearings in the X carriage) with spring underneath as shown. (4.6) The two cap screws you put in the X end idler are adjusters that counteract the force of the X axis belt pulling in the X ends. The screws push on the ends of the X axis smooth rods.

You can set the X axis to a particular width, so that when you attach it to the Z axis smooth rods it doesn’t bind as it goes up and down.

Assuming your Z smooth rods are parallel!

Adjust the cap screws to ensure the clip bearings align with the Z bars. Replace the Z smooth rod you removed earlier, and pinch up the bar clamps so it holds it in place. Offer up the clip bearings on the X axis to the Z axis smooth rods. You should find the idler bracket needs adjusting outwards to correct the alignment. Tighten the adjustment cap screws in the end of idler bracket to push the X idler out, making the X axis wider.

Next thread the M5 studding into the nuts in the X end. Try to thread them in evenly such that the bracket is roughly half way along each piece of studding.

Loosen the Z smooth rod clamp at the bottom and the Z motor mount at the top on both sides, just enough so that you can slide the smooth rods up. Insert the Z smooth rod into the X motor mount clip bearings on the side of the machine with two linear bearings in Y. Tighten the Z axis smooth rod clamps, top and bottom. Use a rectangular object to support the X carriage on the Y Frog.

Slide the other Z axis smooth rod up, and then down through the X axis clip bearings, into its clamps and tighten. Check the X axis moves smoothly up and down; adjust the X idler screws if necessary.

Screw the ends of the M5 rods into the plastic tubes on the motors. Leave a gap of about 2mm to 3mm between the tops of the M5 rods and the bottoms of the motor shafts. (You can see this because the poly tube is transparent.)

(4.7)

Use the M2.5 washers, nuts and cap screws to clamp the endstop to the endstop holder. You’ll notice that the endstop holder has four holes.

The endstop should be clamped to the inner most two holes, with the nuts on the large flat side and the lever facing towards bar clamp.

Use the remaining M3 fasteners to attach the bar clamp to Z smooth rod on the X motor side.

The endstop should be positioned such that it is it is hit by the Z endstop adjuster cap screw.

The picture (4.9) shows the lever arm of the microswitch removed. The lever arm should snap off quite easily; just fold it back on itself.

If you leave the lever on, you will need to cut down the length, because it is too long. It will either hit the Z smooth rod, or the Z leadscrew.

4.8 Required components

X belt

Items Quantity Printed endstop holder . . . . . . . . . . . . . . . . . 1 Microswitch . . . . . . . . . . . . . . . . . . . . . . . . . 1 M2.5 x 16mm cap screws . . . . . . . . . . . . . . 2 M2.5 washers . . . . . . . . . . . . . . . . . . . . . . . . 4 M2.5 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 M3 x 20mm cap screws . . . . . . . . . . . . . . . . 1 M3 nut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 M3 washer . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Next take the remaining belt from when you part assembled the X axis, and insert the free end into the slot in the right end of the X carriage so that it locks with the teeth of the small length of belt. It should ideally be placed as far into the slot as possible so that the end touches the edge of the narrow gap in the centre of the carriage. Then feed the belt through the X end Idler, around the small bearing, back through the carriage, around the motor pulley and back into the slot on the X carriage as shown below.

The tension of the belt is set just like the Y axis.

(4.10)

4.9 Z endstop mounted

4.10 X belt assembly

Z endstop

18 | Frame Assembly

Chapter 5: Heatbed assembly Contents Goal 7 Tools 7 Main assembly 8

Wiring 9 Attach to the machine 10

Goal

Tools M5 allen key Cross-head screwdriver

Multimeter Soldering iron and solder

20 | Heatbed assembly

Items Quantity Lasercut insulator . . . . . . . . . . . . . . . . . . . . . 1 PCD bed heater . . . . . . . . . . . . . . . . . . . . . . 1 Glass printing plate . . . . . . . . . . . . . . . . . . . 1 Foldback spring clips . . . . . . . . . . . . . . . . . . 4 M5 x 40mm screws . . . . . . . . . . . . . . . . . . . 3 19 x 7mm spring . . . . . . . . . . . . . . . . . . . . . . 3 M5 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 M5 washers . . . . . . . . . . . . . . . . . . . . . . . . . 12 M5 nylock nuts . . . . . . . . . . . . . . . . . . . . . . . 3 M3 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 M3 washers . . . . . . . . . . . . . . . . . . . . . . . . . 4 10K glass bead thermistor . . . . . . . . . . . . . . 1 2-way ribbon wire . . . . . . . . . . . . . . . . . . . .0.8m .

20A wire . . . . . . . . . . . . . . . . . . . . . . . . . . .0.5m .

3mm LED . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1k resistor . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Aluminium heat spreader . . . . . . . . . . . . . . . 1 M3 x 16mm countersink screws . . . . . . . . . . 4 3mm dia. heatshrink (black) . . . . . . . . . . 30mm ...

5.5mm dia. heatshrink (grey) . . . . . . . . . 30mm ...

Cable tie . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

5.3 Ribbon wires marking

5.1 Required Components

Main assembly At this stage you will have a long piece of 20A wire (usually twin core flex, 1.6m long). Cut 0.5m off of it to use for this stage.

Get the 2-way ribbon wires by stripping them off the wider ribbon cable supplied with the kit (in the ‘extruder kit’ bag). There are plenty of wires to spare.

If that ribbon cable has a coloured stripe down one side, strip the two wires furthest from it. If it has no coloured stripe, strip from one side, then put the remaining ribbon flat on the bench and run a felt-tipped marker down one side.

(5.3)

5.4 Heat bed assembly

5.2 Heat bed components This will make the wires in it easier to identify later. Set the wider ribbon aside for later use.

Use the countersunk screws together with four nuts and washers to sandwich the heated bed PCB between the aluminium plate and the MDF insulator. Then use a further four nuts to tighten against the nut already in place. (5.4) The zig-zag heater track on the PCB faces up towards the aluminium plate.

Make sure that the PCB solder terminals, the rectangular cut in the insulator, and the notch out of the aluminium plate all line up.

Take care not to break the lasercut springs in the corner of the insulator. (5.5)

5.5 Heat bed insulator

Heatbed assembly | 21

5.6 LED insertion

5.7 LED and resistor in series

5.8 Glass bad thermistor

Bend the LED’s legs and resistor legs as shown above and insert them from the MDF insulator side. The longer LED leg goes to the end marked +. (5.6) The LED and the resistor are in series, and the two of them together are in parallel with the main heater element.

Solder the LED and the resistor as shown on the aluminium plate side. You may find this easier if you prop the bed up on something clear of the bench. (5.7) Trim the wires flush with the top of the PCB using side cutters. Make sure that the connections do not project higher than the thickness of the aluminium plate, or they will foul the glass plate which will go on top of it.

Locate the 10K Glass Bead thermistor. This is very small and can get lost in the folds of the bag. (5.8) Solder the twin ribbon wires onto the thermistor (5.9). Stagger the connections. Use the insulation stripped from the short connection to insulate the thermistor wire.

Tin the ends of the wires, then tin the wires on the thermistor, then sweat them together.

Insulate the joins with a length of heatshrink.

(5.10) Strip the insulation from the other ends of the wires and use your meter to check the resistance. It should be about 10K ohms, though the exact value will depend on room temperature.

Bend the thermistor at right angles and tape it to the bed. Make sure it goes through the hole in the insulator and the hole in the PCB and touches the aluminium plate. If you like you can add a little heatsink grease to improve the thermal contact between the thermistor and the plate.

Pack the hole in the insulator with something fluffy: cotton wool or a bit of scrunched tissue both work well. Put tape over the hole. (5.11) Lead the wires to the edge of the bed where the two cable-grip holes are and tape them down.

Use the holes on the side marked -. Note the strain relief loop; don’t run the wires straight.

Put the glass plate on the aluminium and make sure that none of the wires nor the LED stick out and foul it.

Use the cable tie to attach the high-current wires and the thermistor wires. Again, note that the high-current wires are not pulled taught.

They have a strain relief loop. Make sure they do not project too far on the MDF insulator side - if they do bend them gently flatter.

Pull the cable tie good and tight (but take care not to break the lasercut insulator), and then clip the excess off it.

5.9 Ribbon wire and thermistor

5.10 Heatshrink on thermistor

Wiring

Bare the ends of the high current wire. Put heatshrink on such that it covers only a couple of mm of the bare strands. (5.12) The picture shows one wire complete, the other ready to be wrapped.

Push the wires through the bed as shown (5.13) and bend them flat against the tinned areas of the PCB (you may need to drill the holes out with a 3mm diameter drill first. Do this from the tinned side to get a clean hole). The wire with the black stripe goes to the side marked -.

Solder the wires. Be generous with the solder (it’s giving both mechanical strength and high current carrying capacity), but again make sure that the join is lower than the thickness of the aluminium plate. (5.14)

5.11 Thermistor taped in place

22 | Heatbed assembly

5.12 High coltage wire - ba

Attach to the machine Put the three long screws through the mounting holes with washers under their heads. (5.15) Put the springs on. The sequence from the screw head goes: 1.

2.

3.

4.

5.

6.

7.

8.

M5x 40mm Cap Screw head M5 Washer MDF insulator M5Washer Spring M5 Washer M5 Nut* M5 Nut

5.13 Power connection

5.14 Power connection

The second to last nut should be tightened as much as possible, so that it compresses the spring until it hits the shank of the cap screw.

Repeat this assembly for all three mounting holes, then insert this assembly into the Y frog - with the last nut sitting directly into the recesses in the printed part. This should then be secured from underneath with the last M5 washers and nylock nuts.

Adjust the screws to get the bed roughly level (measure the heights of the corners above the

Y rods with digital callipers).

Tighten the nuts against the Y carriage to secure the bed. (5.16) Fit the glass plate using the four clips and check that the Y axis moves freely back and forth. Then take the glass off and put it in a safe place - you don’t want to break it as you build the rest of the machine...

At this stage your machine should now look like this. (5.17)

5.15 Mounting screw assembly

5.16 Heatbed mounting

5.17 Completed heat bed assembly

Chapter 6: Extruder drive assembly Contents Goal 23 Tools 23 Assembly 24

Goal

Tools

Fitting the drive The Tongue Idler tensioning

25 25 25

24 | Extruder drive assembly Items Quantity Large integral gear (printed) . . . . . . . . . . . . . 1 Small push-fit gear (printed) . . . . . . . . . . . . . 1 Main block (printed) . . . . . . . . . . . . . . . . . . . 1 Frame clip (printed) . . . . . . . . . . . . . . . . . . . 2 Tabbed frame clip (printed) . . . . . . . . . . . . . 1 Flat motor spacer (printed) . . . . . . . . . . . . . . 1 M3 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 35mm M3 cap screws . . . . . . . . . . . . . . . . . 2 30mm M3 cap screws . . . . . . . . . . . . . . . . . 2 20mm M3 hex head screws . . . . . . . . . . . . . 1 20mm M3 cap screws . . . . . . . . . . . . . . . . . 1 16mm M3 cap screws . . . . . . . . . . . . . . . . . 2 12mm M3 cap screws . . . . . . . . . . . . . . . . . 1 M3 washers . . . . . . . . . . . . . . . . . . . . . . . . . 8 3mm 623 bearings 10mm OD x 4mm thick . 3 8mm M3 hobbed drive . . . . . . . . . . . . . . . . . 1 NEMA 17 motor . . . . . . . . . . . . . . . . . . . . . . 1

Start by assembling the geared filament drive.

Take the 20mm M3 hex screw and insert it into the large drive gear. Make sure the flats of the hex head are aligned with the hexagon of the recess. Put the 20mm M3 hex screw with the thread running all the way to the top through the nut then screw on the other parts. The order goes: 1. Hex head 2. Gear 3. 623 bearing 4. Hobbed insert

You will notice that the hobbing on the insert is not in its centre. Put the insert on so that the hobbing is away from the gear end and the conical chamfer is against the bearing.

After putting the bearing on, but before the hobbed insert, place a small blob of superglue or threadlock on the screw threads, about 5mm from the bearing. Then screw on the hobbed insert. (6.2) Do the hobbed insert up tight with your fingers.

Next put a 623 bearing in the back of the drive block as shown (6.4). You may need to clean the hole a little. Use a 10mm drill bit twisted carefully in the hole by hand. While you are at it, clean the hole at the other side too.

Push the gear and hobbed insert assembly that you just made into the opposite side of the block to the one that you just put the bearing into. Check that the hobbing is centred where the filament will run by looking in the unoccupied idler bearing hole in the side of the drive block (poke a length of filament down the 2mm hole in the top of the block if you can’t tell where this is).

Take the gear and hobbed insert assembly out of the block for the moment.

Mount the block on the motor using two 16mm M3 cap screws. Put the spacer between the block and the motor. The motor wires are at the back right in this picture. (6.5) Fit the idler bearing using the 12mm M3 cap screw as shown (the screw needs no nut to retain it).

6.2 Hobbed insert on drive gear

6.3 Hobbed insert on drive gear

6.4 623 bearing in drive block

6.5 Block mounted on motor

6.6 Small gear and bearing fitted

6.7 Gear and hobbed insert in place

Assembly

6.1 Required components Fit the small gear. You may find this easier if you use a sharp blade to put a slight chamfer on the underside of the gear where it meets the motor shaft. (6.6) Push the small gear onto the shaft such that its top is flush with the end of the shaft. You may need to tap it with a soft hammer or block of wood - take care, and support the back of the motor shaft as you do this, rather than the motor’s body.

Push the gear and hobbed insert assembly into its hole in the block. Rotate the gear as you do this so that it meshes with the small gear on the motor. (6.7)

Extruder drive assembly | 25 Fitting the drive Use the three U clips together with cap screws nuts and washers to mount the drive on the top two frame bars of your Mendel as shown.

You can do this with the large gear removed, to make it easier. For extruders with NEMA17 motors (same as X, Y and Z axis motors) the tabbed U clip is optional, and will not be included with new kits.

The two holes above the large gear hole act as the idler tensioners. One of the also secures the extruder to the frame. Put a 30mm M3 cap screw and washer into the hole nearest the gears, with a nut (no washer) in the groove on the other side. Leave this loose for the moment.

In the hole closest to the motor, use a 35mm M3 cap screw and washer, put the tabbed frame clip on the opposite side with the screw going through the tabbed part, secured with a nut and washer.

Tighten the nuts on both of these screws until they just touch the surface against which they bear, but no tighter. Later you can adjust these for idler tension on the filament.

Clip the two plain frame clips onto the rear piece of studding. The block is secured to one clip by dropping an M3 nut into the upper slot shown on the picture above and using a 35mm M3 cap screw. The other is secured by a 30mm M3 cap screw with a washer, and a M3 nut and washer on the other side. (6.10) The tabbed frame clip (if it is included in your kit) is not necessary; the extruder block can just rest on the other threaded rod. (6.8 & 6.9) If you wish to fit it, clip it over the front piece of studding at the top of the frame, and secure the clip with a 20mm M3 cap screw and washer, and a nut and washer. The extruder can just rest in the slot, on the longer bolt.

The filament will feed over the front, with the Bowden cable running to the rear (Y motor side).

6.8 Tabbed frame clip not included

6.9 Tabbed frame clip included

6.10 Mounted extruder drive

6.11 The tongue

The Tongue You will be left with one small part left over; the tongue. This goes in the slot in the top of the extruder, below the large gear. It will hold the Bowden cable into the extruder drive, and is fitted in the next section of the instructions.

Keep it safe for the moment. (6.11)

Idler tensioning In order to tension the idler mechanism, tighten the two M3 cap screws and nuts mentioned earlier until the point that the drive block has sufficiently flexed that the two sides of the slot just touch at the top.

Feed a length of filament through the drive by turning the big gear by hand. When you hold the gear still, it should not be possible to pull the filament back out of the drive by hand. If it slips, tighten the two nuts slightly.

6.12 Completed extruder drive

26 | Extruder drive assembly

Chapter 7: Hot end assembly Contents

Goal 27 Tools 27 The hot part of the hot end 28 The nozzle 29 The bowden tube 29 The cooling system 29

Goal

Hotend assembly 30 Hotend wires 30 Ribbon Cable 31 Connecting up 31 Installation 32 Nozzle mounting brackets 32 Fitting hot ends 32 Finishing off 32

Tools Allen key Small screwdriver Pliers

Adjustable spanner Heat sources (small blowtorch / soldering iron) Bench vice

28 | Hot end assembly Items Quantity Heater block and nozzle 100k thermistor . . . . . . . . . . . . . . . . . . . . . . 1 PTFE (clear) heatshrink sleeve . . . . . . . . . . 1 Aluminium heater block . . . . . . . . . . . . . . . . 1 Crimps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Polyolefin (black) heatshrink sleeve (20mm) 2 Stainless steel one-piece nozzle . . . . . . . . . 1 2mm (ID) x 3mm (OD) PTFE tubing (20mm) 1 Bowden cable PTFE tube . . . . . . . . . . . . . . . . . . . . . . . . . .

Slotted brass union . . . . . . . . . . . . . . . . . . .

Threaded brass union . . . . . . . . . . . . . . . . .

Tongue (printed) . . . . . . . . . . . . . . . . . . . . . .

1 1 1 1

Cooling system Aluminium cooling block . . . . . . . . . . . . . . . .

Fan and heatsink . . . . . . . . . . . . . . . . . . . . .

M3 x 25mm screws . . . . . . . . . . . . . . . . . . .

Cable ties . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 1 2 1

Assembly Brass tapered nut . . . . . . . . . . . . . . . . . . . . .

Heater cartridge . . . . . . . . . . . . . . . . . . . . . .

Double coil spring washers . . . . . . . . . . . . .

M3 x 16mm screws . . . . . . . . . . . . . . . . . . .

1 1 2 1

Wiring 10cm high current wires (motor excess) . . .

Polyolefin (black) heatshrink sleeve (15mm) Pin header . . . . . . . . . . . . . . . . . . . . . . . . . .

8-way ribbon cable (1.2m) . . . . . . . . . . . . . .

Crimps . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 6 2 1 2 7.1 Required components

The heater cartridges for the Mendel/Tricolour has red leads as shown in the picture beside the table above, the huxley cartridge is similar but comes with white leads.

There are several stages in this construction where you have to trim pieces of PTFE. It is essential to clear any swarf created away and not to let it get into the extruder. PTFE swarf will travel to the nozzle and block it if it is allowed to contaminate the device.

7.2 Thermistor and heatshrink

The hot part of the hot end First fit the thermistor. For this step, you will need the axial thermistor, length of PTFE (clear) heatshrink and the heater block. (7.2) Cut the PTFE heatshrink such that when slid over the thermistor, approximately 5mm of the leads are bare at each end. With the PTFE heatshrink in position, use a heat source to shrink the PTFE around the thermistor bead and leads. PTFE heatshrink requires

temperatures in excess of 300C to shrink. A naked flame will do for this. Keep the flame moving whilst shrinking the PTFE. Take the sheathed thermistor, and slide one lead into the small hole in the heater block.

With the thermistor bead up to the side of the heater block, the PTFE heatshrink should protrude form the other side of the block. Grasp the PTFE heatshrink with some pliers, and pull the thermistor through until the bead is roughly in the centre of the heater block. (7.3)

7.3 Thermistor in heater block

7.4 Nozzle and PTFE tube

Hot end assembly | 29 The nozzle

The bowden tube

The cooling system

It is essential that the nozzle is free from contamination before assembly.

Use a sharp blade to trim a few millimetres off the end of the tube at right angles to get a clean square end.

Now you will assemble the cooling system.

Some heatsinks come with a sticky backing which you will need to peel off. This can be quite tough - you may need to pull with pliers.

Metal swarf from manufacturing may still be inside it. The best thing to do is to rinse it in a degreaser, use a rolled up piece of tissue to pull out any large parts, rinse in Acetone, and blow air through from the nozzle end. Check you can see daylight all the way through it.

We will need a short length (about 10mm) of 3mm diameter PTFE tube to line the cold end of the one-piece nozzle. (7.4) Using a sharp blade, cut one end of the PTFE liner. Try to make the cut as square to the axis of the tube as possible. Push this into the counter-bore at the cold end of the one-piece nozzle. Again using a sharp blade, cut the PTFE liner flush with the cold end of the onepiece nozzle. (7.5)

Screw the tube into one of the brass unions.

Look in the other end (a magnifying glass is useful) to see when it gets to the end of the internal thread, then stop. If you have trouble starting the threading, make a small cone on the end with a pencil sharpener. Don’t cut too far - PTFE is very soft. The cone makes it easier to start the thread.

Screwing the tube in will have reduced its internal diameter slightly. Gently twist a 2mm drill by hand in the end of the brass to thin the tube where it is inside the screw thread. If you have a small hand-chuck this is made easier.

Repeat the process with the other brass union, putting it on the other end of the tube. (7.6)

Take the heatsink and the cable tie. You’ll notice that one edge of the heatsink has two holes for mounting. Insert the cable tie around one of the fins on the opposite end of the heatsink. This will be used to assist with wiring later. (7.7) You can put a little heatsink grease on the aluminium cooling block if you like. Attach it to the fan with the two M3x25mm capscrews.

Feed the screws in through the fan, through the heatsink and into the cooling block. (7.8) Now screw the brass bowden end piece (with the PTFE bowden tube screwed into it), into the Aluminium heatsink block (the long thin one with five holes in it). (7.9) Once fully screwed in, screw the free end of the barrel into the M5 hole in the Aluminium heatsink block until it meets the brass piece.

Now unscrew the brass piece by 1/4 turn, screw the barrel in to meet it, and finally tighten the brass piece with some pliers. This will result in the barrel and bowden end pieces being locked together inside the heatsink block. (7.10)

Take a 5mm drill and gently twist it against the end of the PTFE that you have just created to dish it slightly. Make sure you clear all swarf away. Now set the one-piece nozzle to one side.

Push a length of 1.75mm build filament down the tube from the other end to clear out any PTFE swarf - any left behind will block your nozzle! Make sure the filament runs freely down the tube and comes out of the far end without impediment.

7.5 PTFE liner in nozzle

7.6 Brass union on tube

7.7 Cable tie on heatsink

7.8 Fan and heatink

7.9 Heatink block

7.10 Barrel and bowden in heatsink block

30 | Hot end assembly the brass tapered nut. Make sure the nozzle extends out of the tapered nut, but not too far.

The nut has the same taper as the nozzle, so try and get them such that the tapers are in line, like the pictures below.

Hotend wires

Next fit the heater cartridge, this just slides into the large hole in the heater block and is held in by friction. Run the wires up around the side of the heatsink and through the cable tie on the top. Keep the wires tight to the side of the fan and bend them to apply positive pressure to the heater cartridge; this will stop the heater cartridge slipping out of the heater block. You can put another cable tie through the fan, to hold the wires at the side, if it still feels loose.

(7.13) The last components to fit are the double coil spring washers. Attach them as shown below using two M3x16mm cap head screws.

You can put an M3 washer above and below each double coil spring washer, if you wish.

Using double coil spring washers allows the height of the nozzle to be adjusted individually, so that multiple nozzles can be leveled.

The hotend is designed to be easily removed for maintenance, so a wire connector can be used to connect the hotend to the ribbon cable.

CAUTION! The next few steps describe wiring up the hot end connector. However, GREAT CARE should be taken doing this. The heater cartridge and the fan wires have 12V (19V with a Huxley) running through them ALL THE TIME. The thermistor wires are 5V, and connect directly to the Arduino chip on the Melzi. A short circuit between the thermistor wires and any of the other wires WILL DESTROY THE TEMPERATURE MONITORING ABILITY OF YOUR MELZI! We regard this as a user error, and your Melzi will NOT be covered by the warranty.

If you doubt your ability to solder the connector correctly, run completely separate wires from the thermistor to the Melzi - just longer versions of those shown directly below. You can still unplug the hot end, it just won’t be one connector.

The following section will take you through connecting your hot end using the FEMALE locking crimp terminal housings, with the MALE crimps. (7.15) Take 2 lengths of wire, each approximately 10cm / 4 inches long. You can cut these from the ends one of the motors - there is plenty of spare wire. Use the green and blue wires so that they don’t get easily confused with the

7.12 Brass nut in place

7.13 Heater cartridge inserted

7.14 Cable tie holding in place

7.15 Female crimp terminal with male crimps

7.16 Wire lengths and female crimps

7.17 Heatshrink on crimps

7.11 Kapton tape on heatsink base

Hotend assembly The final step is to assemble the hot part of the hotend with the cooling system.

You can cut a small piece of Kapton tape and stick it to the bottom of the fan heatsink. A small amount of air comes out the bottom of the heatsink, so the heater has to work a little more, but it is not significant. On Tricolour hot ends, it’s probably best to leave the Kapton off, as it will help cool the hot ends between tool changes. (7.11) Now screw the heater block onto the onepiece nozzle. Orientate the heater block so the thermistor is closest to the tip of the nozzle, away from the heatsink block. Follow it with

IMPORTANT: Tighten the brass tapered nut and heater block together tightly with spanners (more than finger tight!); this will ensure the threads make good contact with the nozzle, and heat transfers well. If you have problems with extrusion despite the temperature being reported correctly, it’s worth checking that the brass tapered nut hasn’t worked lose. (7.12)

Hot end assembly | 31

7.18 Wiring diagram

red/black wires of the fan and red wires of the heater cartridge.

To connect to the thermistor: use the crimps in a strip of 5, NOT the male crimps for the housing (7.16). Fit a crimp terminal to each wire, and sheath using the black Polyolefin heatshrink. (7.17) These pins just push onto the thermistor wires.

(7.14) Fit 6x MALE crimp terminals to the free ends of the hot end wires, ready to push into the FEMALE locking housing.

Insert the crimps into the FEMALE locking housing. The sequence should be as follows (7.18) The housing has a small embossed ‘1’ and ‘6’ number on it, so you can orientate it as the diagram above. You can just see the ‘1’ in the picture below, on the top right of the housing.

The ‘6’ is on the other side of the housing.

(7.20 & 7.21)

Ribbon Cable

7.19 Wiring diagram

Get the 8-way ribbon wires by stripping them off the wider ribbon cable supplied with the kit (in the ‘extruder kit’ bag). There are plenty of wires to spare.

Using the FEMALE crimp terminals, crimp them onto the ribbon cable wires. The 4 (four) middle wires of the ribbon cable are twisted into 2 (two) pairs to carry the required current to the hotend cartridge heater.

Push the crimps into the MALE housing. The housing has a small embossed ‘1’ and ‘6’ number on it, so you can orientate it as the diagram. (7.19) (7.22 & 7.23)

Connecting up

7.20 Crimp terminal connection

7.21 Crimp terminal connection

7.22 Male housing and crimp terminal

7.23 Ribbon cable crimp connection

Bend the wires up the side of the heat sink.

Do not pull them tight - they need a little slack to accommodate movement and expansion.

Attach them at the top of the heatsink with two cable ties chained together, one of them running through the top slot in the heatsink.

Trim the excess off the cable ties.

Use a meter to check that the resistance between the wires and the aluminium block is infinite and that nothing is shorting.

Also check the resistance of the heater cartridge and the thermistor by measuring from the far ends of the wires. The Mendel heater should be just under 3 ohms or the Huxley just under 7 ohms. The thermistor should be about 100K at room temperature.

32 | Hot end assembly

7.24 Required components

7.25 Nozzle mounts

7.26 Hot end fitted

7.27 Tube connection

7.28 Tube inserted

7.29 Tongue in place

Installation

Fitting hot ends

Finishing off

Items Quantity M3 x 25mm cap screw . . . . . . . . . . . . . . . . . 4 M3 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Printed nozzle mount front . . . . . . . . . . . . . . 1 Printed nozzle mount rear . . . . . . . . . . . . . . 1

Then use the M3x16mm cap screws in the aluminium cooling block to attach the extruder hot end to the X carriage of your Mendel.

The PTFE tube clips into the printed vertical channel in the X carriage. The springs should fit underneath the lip of the x carriage. Therefore the order is cap screw, x carriage, (optional M3 washer), spring, heat sink block. The optional M3 washer lets the springs sit flat against the printed X carriage. Fan and heatsink removed in the picture above only to show mounting, DO NOT remove yours. Make sure your hot end heater cartridge is fully inserted into the heater block, NOT like the picture! (7.26) Generally, you can fit the hot end in any of the available slots; you set the final position of the nozzle on the corner of the bed using the M206 gcode (instructions in ‘Printing’). If you’re building a Tricolour, our standard layout is to fit the first extruder on the front left space.

Put the free end of the PTFE tube in the extruder drive - the tube should run outside the machine, not between the threaded rods.

Secure it with the printed tongue, placing it in the available slot. The thin end of the tongue goes towards the outside, locking the slotted brass union in place. (7.27 - 7.29)

Nozzle mounting brackets You’ll notice the nozzle mounts are slightly different. The front mount has circular holes for housing the head of the cap screw, the rear mount has a hexagonal hole for the M3 nuts. The mounts are otherwise identical, so it doesn’t really matter which way around you put the mounts on.

Insert the cap screws through the holes in the front nozzle mount, through the holes in the x carriage and secure using an M3 nut in the rear nozzle mount.(7.25)

The above pictures show filament in the drive and tube already; the tube can be fitted and released with or without filament in it.

Twist the ribbon cable loosely round the PTFE tube to the top, as shown in the picture at the top of this page. Wrap it 10 turns. Do not pull it tight.

Attach the glass plate to the bed with the four foldback clips.

Chapter 8: Wiring Contents Goal 1 Tools 1 Frame triangles 2 Cross bars 3

Put them all together Z-motor mounts, diagonal, and power connector Smooth Rods Aligning the frame

Goal

Tools Wire strippers Multimeter Soldering iron

Small screwdriver Vice

3 4 5 5

34 | Wiring By the end of this stage your machine will be ready to commission.

All the wires from electric components in the machine run to the controller electronics.

What you are going to do is to route those wires round the frame from each component to the controller, leaving a generous extra length when the controller is reached and not at that time connecting the wire to the controller.

Then, when all the wires have been attached to the frame with cable ties, you will trim them and make the final connections to the controller.

You can route wires and attach them with cable ties as you go. You will then have to clip off those cable ties when a new wire runs on the same route and add a new one holding both wires. This is slightly wasteful, but easy.

If you click on the pictures below, you will be taken to a high-resolution version. This will help to make details clear.

If you need to identify wires (there are quite a few) then you can use the type of sticky tape called “invisible” tape. This has a surface that you can write on with a felt-tipped pen. Just put a loop of tape round the end of a wire and write “X-endstop” (or whatever) on the tape. You can either remove your labels when everything is connected and tested (neat) or leave them on (convenient if you dismantle the machine later).

Particularly useful is to tape together and label the five sets of four motor wires at their ends furthest from their motors. This helps prevent tangles when you are threading the wires, and you can easily identify them when you come to wire up the controller.

Items Quantity ‘Melzi’ controller PCB . . . . . . . . . . . . . . . . . . 1 20A High-current wire (0.55m) . . . . . . . . . . . 1 10A High-current wire (0.5m) . . . . . . . . . . . . 1 Printed U clips . . . . . . . . . . . . . . . . . . . . . . . 3 M3 x 25mm screws . . . . . . . . . . . . . . . . . . . 3 M3 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 M3 washers . . . . . . . . . . . . . . . . . . . . . . . . . 3 Cable ties . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Note: two types of high current wire come with the RepRapPro Tricolour kit; 20A and 10A. The 20A wire is thicker, you have a longer length and comes with the main wiring. This should be used for the power wiring for the heated bed, Melzi and the power supply. The thinner 10A wire is for supplying power to the slave.

Setting the motor currents If you have purchased a machine from RepRapPro, this is already been done for you.

If not, or if they need adjusting for any reason, this process is described on page XX.

8.1 Required components

Wire routes

In what follows you will find the routes of the individual connections superimposed on this picture (8.2). It is taken from the back of the machine, and the side of the machine on the picture’s right is therefore the left side of the machine when it is viewed from the front in its normal working position.

Almost all the wiring runs down the triangle threaded rod to the fore of the picture, and then along the triangle threaded rod at the bottom.

Important: rules for wiring up You will do serious damage to your RepRap electronics if the power is connected backwards. Other damaging mistakes are to short out high-current devices like motors and heaters, and to connect high-voltage devices like stepper drivers to signal inputs like temperature sensors.

So - in the sections below where it tells you to check things - please check them thoroughly. It is worth taking the time...

Also important for the steps below: when attaching wires to screw connectors, strip about 5mm of insulation off them, twist them between your fingers, and tin them with solder. The tinning is needed for good contact, and to ensure that fraying does not cause shorts.

When wires leave a device (like a motor) or arrive at a connection (like the screw connectors on the controller) leave a small slack length (about 20mm long) for strain relief - don’t have the wires taut.

Finally, when making any changes to the wiring or any other electrical aspect of the machine, first disconnect both the power and the USB. Failing to do so could damage your electronics.

8.2 Diagram of printer

Wiring | 35

8.3 Controller board attachment

8.4 Wiring the power supply

Attaching the control electronics

The power supply wire

Attach the three U clips to the frame as shown (8.3). The controller board goes on the left hand side of the machine at the front (that is, the side of the frame that is on the same side as the X motor, on the side opposite the Y motor).

Adjust the positions of the U clips so that they line up with the holes in the PCB and the PCB is vertical.

Attach the board to the clips with the screws, washers and nuts. The order goes: 1. screw head 2. washer 3. PCB 4. U clip 5. nut Facing the machine from the front, the components on the PCB should be away from the triangle frame and the USB connector and SD card holder should be at the top of the PCB pointing to the front.

Read through all of this section before starting work on it.

In what follows take great care that there are NO filaments of wire that are sticking out from twisted bundles. These can cause shorts, and may damage the power supply or electronics.

Detach the XLR plug from the frame vertex at the back.

If you are building the single-colour version of Mendel, do this: Cut 55cm from the 20A wire. The rest is used for the heated bed and power supply. Bare the high-current wire ends, and split each end in two equal halves. Twist those halves separately.

The pin numbers are embossed on the black part of the plug, next to each pin.

Solder the two from the wire with the black stripe (the Ground - GND wire) to Pin 1 and the plug shell tab.

Solder the two from the plain wire (the +12 volt wire) to Pins 2 and 3.

The picture above (8.4) shows the GND connections made, and the +12 volt connections about to be made. The unsoldered fork in the picture going to Pins 2 and 3 is shown a little long; the bared wires need to be about 2/3 the length shown.

Trim the excess wire from the tab with side cutters.

Fit the XLR plug back in the machine. The illustration (8.5) shows the route of the power wire coloured pink. Leave a small loop at the XLR plug free for strain relief. Attach it with tape or cable clips to the bottom rung of the triangle, but leave the controller board end free for the moment.

If you are building the single-colour version of Mendel skip to the next section.

8.5 Power supply wire

Note: two types of high current wire come with the RepRapPro Tricolour kit; 20A and 10A. The 20A wire is thicker, you have a longer length and comes with the main wiring. This should be used for the power wiring for the heated bed, Melzi and the power supply. The thinner

10A wire is for supplying power to the slave.

The thicker 20A wire going to the master controller board is 55cm long, and the thinner 10A wire for the slave controller that is 50cm long. Wire one into the tab (black stripe) and Pin 2 (white), and the other to Pin 1 (black stripe) and Pin 3 (white). You may need to remove a few strands from the wires to reduce their diameter so they fit in the holes in the plug. Then connect Pin 1 and the tab with a small piece of thick wire. Do the same with Pins 2 and 3.

Fit the XLR plug back in the machine and run the longer master power wire as described for the Mono machine. Run the shorter slave power wire along the frame triangle base to the slave controller position. Make sure that the two free ends of this wire are separated, and wrap a little tape round the ends to insulate them temporarily.

The heated bed wires Bare the ends of the two thin wires from the bed (the thermistor wires) and use your meter to check the resistance between them. It should be about 10K ohms (though this will depend on room temperature).

Push the meter probes in the ends of the thick wires (the bed heater PCB). The resistance should be about 1.5 ohms.

Run the power wire and the thermistor signal wire from the heated bed along the route shown. (8.6) Check that the bed of the machine can run freely from one Y extreme to the other without the wires pulling taught and without their catching on anything (particularly the M5 screw that drives the Z axis and the endstop).

Again, don’t attach the wires to the controller for the moment.

8.6 Heated bed wires

36 | Wiring

8.7 X motor wires

8.8 Y motor wires

8.9 Z motor wires

The X motor wires

The Y motor wires

The Z motor wires

Run the X motor wires along the route shown (8.7). Leave a generous loop in free air.

Remember that the Z axis has to be able to move up and down its full length. It’s helpful to move the Z axis to the very top of the frame to ensure you have enough wire.

Don’t attach the wires to the controller.

Run the Y motor wires along the route shown (8.8). They attach to the bottom threaded rod of the frame at the back. Again, don’t attach the wires to the controller.

The two Z motors are wired in series as shown in the diagram (8.10). It doesn’t matter which motor in the diagram is the left one and which the right - the result will be the same. Run the Z motor wires along the routes shown. Make the joins where indicated.(8.9) To make the join bare about 10mm of each wire. Put a short length of heatshrink on one.

Form each end into a V (blue wire), hook them together, and then close the Vs (red wire).

Solder the join (with the heatshrink further away than shown - you don’t want to shrink it prematurely). (8.11) Move the heatshrink over the join and shrink it with the hot barrel of the soldering iron (don’t use the tip - that will make a mess of solder on the outside of the heatshrink.)

Don’t attach the wires to the controller.

The endstop wires

8.10 Z motor wiring diagram

8.11 Wire jointing

8.12 Endstop wiring

Cut the ends off the motor wires at the controller board end. Make sure you leave a generous length on each to connect to the controller. If you taped and labelled you motor wires, put new labels just on the motor sides of the cuts before you make them.

Connect your endstops using two wires each.

It is a good idea to use a different colour for each axis as this will make it easier to get the endstops connected to the correct input. You should now have plenty of multi-colour wires trimmed from the stepper motors.

For each microswitch, solder a separate wire to each of the outer legs of the switch, then cover with some heatshrink to insulate the joint. These are the NC (Normally Closed) and C (Common) connections; RepRap expects the switch to open when the endstop is hit.

Put the endstops and their h clips back on the machine. (8.12)

Wiring | 37

8.13 X endstop wires

8.14 Y endstop wires

8.15 Z endstop wires

The X endstop wires

The Y endstop wires

The Z endstop wires

The X endstop wires run along the same path as the X motor wires. (8.13) Cable clip all the wires together where they loop free in the air. Get all wires in the loop the same length for neatness (Hint: don’t pull the cable ties fully tight. Then you can slide the wires through them to get everything neat before tightening.)

Don’t attach the wires to the controller.

The Y endstop wires run along part of the route of the Y motor wires. (8.14) Don’t attach the wires to the controller.

The Z endstop wires run along the route shown (8.15). Leave a good loop from the switch to the point where it first connects with the frame.

You will need to adjust the height of the switch.

Don’t attach the wires to the controller.

8.16 Extruder motor wires

Connections to the controller board

8.17 Hot end ribbon cable

The extruder motor wires

The hot-end ribbon cable

Run the extruder motor wires along the route shown. (8.16) Don’t attach the wires to the controller.

The hot-end ribbon cable should already be loosely wound round the PTFE filament feed tube. Attach it to the frame along the route shown. (8.17) Don’t attach the wires to the controller.

First make sure that all the moving parts of the machine can move freely for their full travel without fouling or snagging any of the wiring.

Remember that the entire X axis has to be free to move vertically.

If you have attached all the wires with tape, now is the time to go round the machine cutting off the tape (don’t cut the wires...) and attaching the wires permanently with cable ties.

What you are going to do is to trim the wires to length, twist them, tin them, and attach them to the appropriate screw connector. When a wire is in its connector the insulation should abut (but not enter) the metal part of the connector.

There should be no bare wire visible.

When you twist and tin the ends of the wires, put them in their connector to check the length.

If any are a little long, trim them with side cutters.

When you tighten the screws in the controller board’s connectors take care that 1. Your screwdriver doesn’t slip and damage the board, 2. You don’t put excessive twist stress on the board or push against it too hard - support it with your free hand.

The port marked ‘fan’ is NOT for the hot end fan. This port is for an optional cooling fan that points directly at the print. This is useful for printing small parts and helps with detailed features when printing with PLA. The hot end fan connects directly to the 12V supply of the Melzi, so that it runs all the time.

38 | Wiring

8.18 Controller board connections

The power wires Cut the wires to length so that they will reach the power connector on the board. The GND (black stripe) wire goes to the top of the connector and will have to be a little longer.

Bare the ends of the wires and twist them tight.

Make sure there is a good length of wire to go into the screw terminal (about 10mm), but not so much that there is bare wire outside of the terminal. Tin the bare wire, but don’t use too much solder, or the result will be too fat to fit in the connector.

Screw the wires into the power connector. As mentioned the GND wire with the black stripe goes to the top, the plain wire to the bottom.

Don’t do the power connector up tight - you are going to have to connect the hot end fan wires to the same connector in a minute.

This is the single most important electrical connection in the machine. If you get it wrong expensive bad things will happen. Take a moment to double check it.

The X motor wires

The X endstop

These go to the bottom connector. From the bottom upwards the sequence is Black, Green, Blue, Red.

The X endstop wires connect to the connector above the unused connector. The polarity doesn’t matter.

The Y motor wires

The Y endstop

These go to the connector above the X motor connector. From the bottom upwards the sequence is Black, Green, Blue, Red (that is, the same as X).

The Y endstop wires connect to the connector above the X endstop connector. The polarity doesn’t matter - you can connect them either way round.

The Z motor wires

The Z endstop

These go to the connector above the Y motor connector. From the bottom upwards the sequence is Black, Green, Blue, Red (that is, the same as X).

The Z endstop wires connect to the connector above the Y endstop connector. The polarity doesn’t matter - you can connect them either way round.

The extruder motor wires

Unused connector

These go to the connector above the Z motor connector. From the bottom upwards the sequence is Black, Green, Blue, Red (that is, the same as X).

The connector above the hot-end heater resistor wire connector labelled “fan” is not used. DO NOT connect the hot end fan to it (see below).

The hot-end heater resistor wires in the hot-end ribbon cable

The bed temperature wires

A reminder from when you wired the hot end: the wires across the ribbon cable in order as shown in the diagram. (8.19) The hot-end heater cartridge wires come in pairs - you connected two wires to each end of the resistor to get a good current carrying capacity.

The hot-end heater cartridge wires go to the connector above the bed power wires, labelled ‘hot end’ Split them off from the hot-end ribbon cable, bare the ends, twist the pairs together, tin them, and fit them in the connector. The polarity doesn’t matter - you can connect them either way round.

The wires that run along with the bed power wires connect the bed’s temperaturemeasuring thermistor. They connect to the connector above the Z endstop connector. The polarity doesn’t matter - you can connect them either way round.

The hot-end temperature wires There are two wires from the hot-end ribbon cable that connect the hot-end temperaturemeasuring thermistor. They connect to the connector above the bed temperature connector. The polarity doesn’t matter - you can connect them either way round.

The bed power wires These go to the connector just above the power input connector. Again the black stripe is the low voltage one and goes to the top. The plain wire is the +12 volts wire and goes to the bottom.

Connect the wires in exactly the same way as the power wires, but do these ones up tight.

Use a finger to support the back of the Melzi PCB when you are tightening screws - don’t let it bend.

8.19 Hot end ribbon cable wiring diagram

Wiring | 39 The hot-end fan wires The hot-end fan wires in the hot-end ribbon cable DO NOT connect to the terminals marked “fan” - those are for optional additional cooling.

Do not connect them to the hot end power or the bed power.

The hot-end fan wires connect to the power connector, in parallel with the 12V power input, so the hot-end fan is on all the time.

Make sure you get the polarity right. You should have marked the fan’s + and - connections when you wired up the fan. Trace them through by counting wires across the ribbon cable.

Slacken the power wire screws and connect the fan wires in parallel with the power.

Tighten these screws firmly - this connector has to carry a large current. Remember to support the back of the circuit board when you are tightening screws to stop it bending.

Never operate your RepRap without the fan connected and running. The hot end needs the cooling at all times.

Testing Set your meter to measure resistance. Short the probe ends. You may find (particularly if your meter is not the most expensive one on the market) that the reading is not quite 0 ohms. Note down what it is - this is your meter’s idea of a dead short. Add this number to the low resistances given below.

Remember that you have a resistance (about 20kohms). You will get incorrect resistance readings if your fingers are touching wires or parts of the circuit.

Put one probe on the casing of the XLR power connector. Put the other on the cover of the SD card socket. The meter should read 0 ohms.

Measure the resistance between the two screws on the power connector. This may start low and then rise; this is the capacitors in the circuit charging up with the tiny current from the meter. It may level out at a few hundred ohms. Anything HIGHER than this, up to infinite resistance, is fine. Anything LOWER than this, down to 0 ohm resistance, indicates a short between +12V and -12V (ground), and MUST be fixed!

Measure the resistance between the two screws on the bed power connector. This should be about 1.5 ohms.

Measure the resistance between the two screws on the hot-end heater resistor connector. This should be about 3 ohms.

Make sure all the moving axes are not touching their endstop switches. Check that each resistance on the X, Y and Z endstop connectors is 0 ohms. That is to say the endstop switches should be closed. Press each switch in turn. The corresponding resistance should rise to 5K ohms or more (the resistance of the circuit components on the controller board in parallel with the switch).

Check the heated bed temperature sensor connector. The resistance should be around 5 to 10 kilohms. This is not just the resistance of the sensor. Other parts of the circuit on the controller board are in parallel with it.

If you are building the single-material/singlecolour Mendel, check the hot-end temperature sensor connector. The resistance should be around 5 to 10 kilohms. This is not just the resistance of the sensor. Other parts of the circuit on the controller board are in parallel with it.

Measure the resistance between Pin 3 on the XLR connector and the +12 volts input screw on the controller board. This should be 0 ohms.

40 | Wiring

Chapter 9: Power supply Contents Goal 41 Tools 41 Safety 42 Mains voltage 42 Initial wiring 42

Connect the power supply 43 The XLR Socket 43 Testing 44 Final Testing 44

Goal

Tools M3 allen key Cross-head screwdriver Tweezers

Multimeter Soldering iron and solder

42 | Power supply Safety RepRapPro Mendel works entirely at low voltage, and there is no danger in putting a finger on any part of the circuitry on the machine itself (though remember some parts are hot).

But the power supply necessarily involves a few mains wires. Mains will kill you if you touch it. So don’t.

There are six soldered mains connections in the power supply. If you are not sure about mains wiring, or your soldering is blobby, prone to dry joints, or in any way un-neat, then get someone who knows what they are doing to help you with the work on this page.

When doing all wiring make sure that connections have no stray wire filaments that may short on neighbouring parts.

Bare the ends of wires, twist them, check for a neat twist with no strays, and then finally tin them.

This is important on the next page (wiring up the machine), but it is really important for wiring the power supply here. The power supply works with both large voltages and large currents, and so careful, tidy work is essential.

Items Quantity 12v Power supply . . . . . . . . . . . . . . . . . . . . . 1 20A wire (as required) . . . . . . . . . . . . . . . . . 1 Mains cable . . . . . . . . . . . . . . . . . . . . . . . . . 1 XLR socket . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Printed cover . . . . . . . . . . . . . . . . . . . . . . . . 1 Mains panel plug . . . . . . . . . . . . . . . . . . . . . 1 LNE mains wires (100mm) . . . . . . . . . . . . . . 1 M3 washers . . . . . . . . . . . . . . . . . . . . . . . . . 8 M3 nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Heatshrink (50mm) . . . . . . . . . . . . . . . . . . . . 1 M3 x 8mm screws . . . . . . . . . . . . . . . . . . . . 2 M3 x 20mm screw . . . . . . . . . . . . . . . . . . . . 1 M3 x 16mm screw . . . . . . . . . . . . . . . . . . . . 1

9.2 Mains voltage switch

9.1 Required components

Mains voltage

Initial wiring

Set the mains voltage for your country. The switch, shown (9.2), is set to 220 volts when the power supply is shipped. This is the failsafe setting: if you plug the supply into a lower mains voltage it won’t work properly, but it will do no harm.

If your country has mains at 110 volts, flip the switch.

Some power supplies are universal - they are designed to work with any mains voltage found in the world. Read the label. For universal supplies there is no switch to set.

Start by soldering the mains wires onto the panel-mounting plug. The picture (9.3) shows European-convention wiring colours: Brown=Live, Blue=Neutral, and Greenyellow=Ground-Earth. The back of the plug has L, N and the symbol for Ground embossed next to the appropriate connection.

Different countries have different conventions on this, of course. The best way to get things right is to connect your mains wire into this plug but not to the mains. Then use your meter to check which terminals on the plug the live and neutral pins on the end of the lead that will plug into the wall socket go to.

When you have soldered the short wires, insulate your joints with short lengths of heatshrink.

9.3 Panel-mounting plug wiring

9.4 Wires in panel

Power supply | 43 Attach the mains plug to the printed panel with the two short screws, two nuts and four washers. You may find that the holes in the plug are slightly undersized (though the specification says 3mm). This does not matter: screw the screws in and use them to cut threads in the plastic - this will give a more secure construction. Then put the washers and nuts on the back.

Put the thick low-voltage wire through its cable grip so it projects by about 100mm. Secure the grip with the 16mm screw, two washers and a nut. Getting the washer under the screw head in is a bit fiddly - you will probably have to use tweezers.

Don’t tighten the grip excessively. Just do the screw up enough to secure the cable so it can’t slip.

Split the low-voltage wire into two leads.

(9.4)

9.5 Screws removed from power supply

9.6 Wores bared and prepared

Connect the power supply

The XLR Socket

Remove all the contact screws from the power supply except the one on the extreme right in the picture. (9.5) Then remove the screw that holds the case together (where the screwdriver in the picture is). Set that aside for use later.

Next, strip, twist and bend the wires. Check lengths and fit before you tin.

For the live and neutral: form the ends into a U that will fit in the connector and be secured by one of the screws.

For the Ground wire and the two fat lowvoltage wires, split the filaments of each end into two equal bundles, twist those separately, then form each of them into a U that will fit in the connector and be secured by one of the screws. (9.6) When you are happy that everything fits neatly, tin all the ends.

Screw the Live, Neutral, and one leg of the Ground wire to the labelled connectors.

Screw the other leg of the Ground wire to the COM or -V terminal next to Ground. This is important: it is the connection that earths all the wiring in your machine.

Screw the two Us of the low-voltage wire with the stripe into the two other COM or -V connections.

Screw the two Us of the low-voltage wire with no stripe into the two +V connections. (9.7) If the tail ends of the Us stick out, trim them with side-cutters. Take care where the cut pieces go - you don’t want them shorting out parts of the power supply.

Finally put the 20mm screw with a washer under its head into the hole in the block on the left as shown and attach the cover to the power supply. (9.8) Take care to tuck the wires neatly inside. You may have to flatten the mains wires so that they lie in the plane of the back face of the plug.

Use the 20mm screw to secure the cover where you removed the short cover screw before. Use that short cover screw with a washer to secure the other end of the cover to the threded hole in the power supply case.

In what follows take great care that there are NO filaments of wire that are sticking out from twisted bundles. These can cause shorts, and may damage the power supply or electronics.

9.7 Wires screwed in

9.8 Panel cover screwed in place

Put the shell of the XLR connector onto the low-voltage wire.

The picture (9.9) shows the ground wire connected, and the +12V wires ready to connect.

Separate and strip the ends. Once more divide the ends into two equal bundles, then twist each bundle.

The pin numbers are embossed on the plastic part of the plug, next to each pin.

The Ground wire (with the black stripe) goes to Pin 1 of the socket and the tab on the outer case.

The +12V wire (plain white - no stripe) goes to pins 2 and 3.

Push the twisted bundle down the connector (the hole goes quite deep). Give each one a good generous amount of solder.

For the Ground/Tab connection, simply push the wire through and solder it as shown in the picture. Then cut off the excess wire with side cutters.

Screw the shell onto the socket. Hold the wire still so that the turning action doesn’t twist it up inside.

9.9 XLR connector wiring

44 | Power supply Testing If any of these tests don’t work, stop, unplug everything, and find the fault before going on.

Switch your meter to measure resistance.

Remember, you cannot measure resistance if the circuit power is on!

Plug the mains wire into the power supply but not into the mains yet.

Important: Check the resistance between the Ground pin on the mains plug and the metal case of the supply. This should be 0 ohms.

Check the resistance between the Ground pin on the mains plug and Pin 1 of the XLR socket.

This should be 0 ohms.

Check the resistances between the case and the Live and Neutral pins of the plug. These should be infinite.

Switch your meter to measure DC voltage.

Put the Ground or Common meter probe in Pin 1 of the XLR socket and the Volts-Ohms-Amps probe into Pin 3.

Plug the mains lead into a socket and switch on the power.

The meter should read +12V plus or minus about 0.3 volts.

Switch off power, unplug the power supply from the mains.

Final Testing Now the most important check: plug the power supply into your RepRap and put the mains wire on the power supply, but DON’T connect it to a mains socket. Measure the resistance between the earth pin on the mains plug and the cover of the SD card socket. The meter should read 0 ohms, or at most a small fraction of an ohm.

If it doesn’t, you have made a mistake. Find it and fix it before you do anything else.

If you are in any way unsure that you have wired the XLR socket incorrectly, do this test: Remove one of the 12V supply wires from the Melzi, making sure it does not touch anything.

Plug in and turn on the power supply, and test you get 12V on the Melzi supply wires, and check the polarity of the wires is correct.

Switch off power, unplug the power supply from the mains, unplug the XLR socket. Replace the 12V supply wires into the Melzi screw terminals, positive wire to positive terminal, negative wire to negative terminal.

Chapter 10: Commissioning Contents Goal 45 Tools 45 Communication 46 USB Driver 46 Pre compiled binary 46 Installing from source 46 Install Python 46 Download software 46 Start talking - Pronterface 46 Confirm settings 47 Axes 47 Motor movement 47 Motors going backwards 48 Endstops and homing 48

Goal

By the end of this stage your machine should be ready to commission.

Tools An object with a measured height (we use a length of 6mm diameter silver steel - the shank of a drill bit works well too).

Aignment 49 Level the X axis 49 Level the bed 49 Bed still not level?

49 Distorted bed 49 Set your Z height 50 Setting offsets 50 Heaters 50 Heatbed 50 Hot end 50 Extruder 50

46 | Commissioning Communication USB Driver If you have a Melzi controller, set the PWRSEL jumper on your controller board to USB. This is the three pin jumper about 20mm left of the processor chip. Short the bottom two pins to power from USB (note this only powers the logic, not the steppers etc). Short the top two to power the board from the main power.

You want the bottom two shorted for this step.

When you are running normally, it should be the top two that are shorted.

Windows Plug the controller into a USB port on your computer. Does the computer complain that it has no driver for the USB device? If so, unplug the USB, then install this driver or find yours in this page. Then, when you plug the controller in, it should register as a COM port on your computer.

Mac Mac users should select a driver appropriate to their machine from: http://www.ftdichip.com/ Drivers/VCP.htm.

As of August 2013, the current driver is named FTDIUSBSerialDriver_v2_2_18.dmg.

This should work for all versions of Mac OS X. You can check in the System Profiler, in the USB list, that an FTDI device shows up.

In Pronterface, connect to your printer through the device named /dev/cu.usbserialXXXXXXXX, where XXXXXXXX is a unique 8 character id. This will appear in the dropdown ‘Port’ list. If you have more than one usbserial device attached to your Mac, you’ll need to remember which new device gets created when the cable is plugged in and remember its XXXXXXXX suffix. If there are no other usbserial devices, then when you run pronterface.py, you will see only one device in the Port list with a name starting with cu.usbserial -- connect to that one.

Pre compiled binary

Start talking - Pronterface

Windows users: We now provide a precompiled version of Pronterface AND Slic3r for simple installation; this means you don’t have to install Python and it’s dependencies.

Currently, this is for Windows only; we are working on versions for other platforms.

Download the Windows version here.

Mac users: We now provide a precompiled version of Pronterface for simple installation; this means you don’t have to install Python and it’s dependencies. This comes WITHOUT Slic3r - installation of that comes on the ‘Printing’ page of the instructions. Download the Mac version here.

For more information on both of these, see the readme on our Github Software page here.

The first thing to establish is that you can communicate with your machine.

Extracting the ZIP file will create a folder called ‘Software’, which contains the communication software Pronterface. (10.1) If you have a Melzi controller, set its power selector jumper to use USB power. The power selector jumper is in the centre of the board; check the jumper is on the two pins furthest from the screw terminals. The jumper is in this position as sent from us; if you have moved it, move it back. Leave the main power supply unplugged for the moment.

Connect your RepRap to a USB port on your computer, then run pronterface.py from the ‘Software’ folder.

Now select the active serial port in the upper left, choose 115200 for the baud rate (or 250000 for older firmware).

Click Connect, wait a moment, and the software will confirm when the printer is online.

(Whenever the controller firmware is rebooted, it will take about ten seconds to respond.)

Installing from source Ignore this section if you have downloaded the pre-compiled binary in the step above. Move on to ‘Start talking - Pronterface’.

Install Python Before you start trying to talk to your machine, you need Python and the dependencies.

Instructions: https://github.com/reprappro/ Software/blob/master/README.md#installingdependencies Windows users: please note that you install the 32-bit versions of all the Python software even if you have a 64-bit machine (that is to say, do exactly what it says on the following link).

Download software You will find our github repo here. The button to download a ZIP file is on the right-hand side of the page (the little picture of a cloud with a down-arrow labelled Download ZIP).

Press the GET POS button, and if the machine returns a position of X0.00 Y0.00 Z0.00 your serial communication is functioning correctly.

IMPORTANT. Next press “Check Temp” and check that both the hot end and the heated bed are reporting a temperature that is around room temperature (it may be a couple of degrees out - the thermistors are designed for accuracy at their operating temperature). If a temperature is too high then there is probably a short circuit in the corresponding thermistor circuit. If it is too low, then there may be an open circuit. Alternatively, your fimrware may have an incorrect setting, see next section. In either case, find the fault and fix it before you go on.

Linux Linux systems should recognize the controller straight away with no need for driver installation. The controller will automatically appear as something like /dev/ttyUSB0 when you plug it in. It is possible that you have to give acess rights to the USB Port (when there is the error message could not open port, permission denied) e.g. for USB0: sudo chmod 666 /dev/ttyUSB0 Or better, on Ubuntu distributions and possibly others, make sure you as a user are a member of group dialout, by running the following command in a Terminal window: sudo usermod -a -G dialout username Replace “username” with your actual user name. Then log off and log back in.

10.1 Pronterface

Commissioning | 47 NOTE: If your pronterface window does not display the custom buttons (GET POS, BL, BR, CENTRE, etc... ), you most likely have installed a version of Pronterface previously, and the settings files .pronsolerc and/or .skeinforge already exist in your main User folder (the one with the main ‘Documents’, ‘Downloads’ and ‘Pictures’ folders in it - usually C:\Users\{username} on Windows). These files are invisible/system files, though; make them visible, delete the folders and reload the software. You should now see the extra buttons.

Confirm settings The Melzi controller runs RepRapPro’s version of Marlin firmware. This allows many machine specific settings to be adjusted from Pronterface, without having to upload new firmware.

First thing to do is to set the EEPROM values to default. You only need to do this once. Send the following commands, by typing it into the command line in the bottom right hand side of the Pronterface window: M502 This sets the defaults. The settings will scroll above the command line, in what we call the log window. Then: M500 This saves the settings permanently (until you do it again) in the EEPROM. The log window should respond with “Settings stored.” Now press the reset button on the Melzi itself; this is in the middle of the board, on the opposite edge from the power connectors. You don’t have to disconnect Pronterface; after a few seconds, the printer will respond and be back online, and a list of the current settings will appear in the log window.

You can check the current settings any time you want, by sending an M503 command to the machine.

The log window should show something like this (These figures may not be the same as yours, it’s just an example of the output!): >>>m503 SENDING:M503 echo:Steps per unit: echo: M92 X91.429 Y91.429 Z4000.000 E945.000 echo:Maximum feedrates (mm/s): echo: M203 X500.000 Y500.000 Z3.400 E45.000 echo:Maximum Acceleration (mm/s2): echo: M201 X2500 Y2500 Z50 E2500 echo:Acceleration: S=acceleration, T=retract acceleration echo: M204 S2000.000 T2000.000 echo:Advanced variables: S=Min feedrate (mm/s), T=Min travel feedrate (mm/s), B=minimum segment time (ms), X=maximum xY jerk (mm/s), Z=maximum Z jerk (mm/s), K=advance_k echo: M205 S0.000 T0.000 B20000 X15.000 Z0.400 E25.000 echo: M206 X0.000 Y0.000 Z-0.250 echo: M208 X150.000 Y150.000 Z97.000 echo:PID settings: echo: M301 P10.000 I2.200 D80.000 W70 echo:Thermistor settings: M304 Hh Bb Rr Tt, H0=Bed, H1..n=nozzle, b=thermistor beta value, r=series resistor, t=thermistor resistance as 25C echo: M304 H0 B4200 R4800 T100000 M304 H1 B3960 R4700 T100000 FPU Enabled no Each setting is displayed, along with a description. To change a settings, send the relevant command and parameter. For example, thermistor readings are interpreted on-the-fly, rather than with a lookup table, so the firmware needs to know the thermistor’s beta value (from the datasheet), the value of the series resistor (which can be seen near the relvevant thermistor connector on the Melzi), and the thermistor’s resistance at 25C. So, to set the nozzle thermistor parameters for a beta value of 3960, a series resistor of 4k7 Ohms, and a 100k Ohms resistance at 25C, send the following command (this is just an example, you don’t need to type this in): M304 H1 B3960 R4700 T100000 Any settings updated from pronterface will take immediate effect, however they will not be saved to EEPROM (non-volatile memory) until you send an M500 command. Following this, the settings will persist following a power off.

Axes Motor movement Do not continue without checking current limits!

If limits are not set, the driver boards will most likely be destroyed Melzi adjustment If you have Melzi controller electronics you should already have set its motor currents as described previously.

Important: Melzi jumper setting Move the power selector jumper (in the centre of the board) to the two pins nearest the screw terminals. This will power the logic from the main power supply, not from the USB. (10.2) Also make sure the autoreset jumper (at the end of the board by the temperature sensor inputs) is not in place; just hang it on one pin for safe keeping. It you don’t do this, the board will reset every time you connect to it... including during prints! (10.3) Plug in your power supply. Watch for smoke in case something has gone horribly wrong!

Also, make sure that the motors and - more importantly - the four motor driver chips - aren’t getting hot. With the current limit correctly set, they should be slightly warm to the touch.

10.2 Melzi power selector jumper

10.3 Melzi Autoreset jumper

48 | Commissioning Take care with the chips - they have internal temperature shutdowns that kick in around 80oC, a temperature that will burn your finger unless you just touch lightly and briefly.

Plug in the USB and run the Pronterface program. Click “Connect” and wait for your RepRap to appear online.

Now type: G1 X5 F500 in the field below the log window and click Send. The X-motor should move to 5mm in the positive direction (X5) at 500mm/min (F500).

Now type: G1 X0 F500 and send. The X-motor should move back to its starting location (X0). If you find that your machine will not move in the negative direction, your endstops are probably not wired correctly.

Refer to the Huxley wiring page or the Mendel wiring page to check your wiring.

Repeat the above test for the Y axis, replacing the ‘X’ in the above command with ‘Y’.

For Z, make the feedrate 200 mm/minute: G1 Z5 F200 Now test the E (extruder) axis: Warning: do not do this whilst you have filament in the extruder. The M302 command allows cold extrusion, enabling the extruder motor to move irrespective of the hot end temperature.

For E type: M302 before sending: G1 E5 F500 You may find that some axes judder or whine but don’t move. This could mean that your frame may not be aligned correctly causing the axis to bind, the belts may not be tight enough (or too tight), or the axis stepper driver current is set a little too low.

To check your frame alignment; for the Y axis, check the smooth rods are parallel, and the bed moves easily with the motors turned off - see the Y axis assembly page. For the Z axis, the X axis may not be very level (see ‘Alignment’ section on this page) or the Z smooth rods may not be parallel (see ‘Aligning the frame’ section on the frame assembly page).

To adjust the stepper driver current, turn off the power, then rotate the appropriate potentiometer just a little to increase the current. Put the power back on and repeat the tests above.

Motors going backwards RepRap works with right-handed Cartesian coordinates relative to the bed not the frame.

That is to say that looking down on the bed from the front of the machine X runs from left to right, and Y runs from front to back (like a graph). Z runs up towards the top of the machine.

Remember that it is the movement of the printing head that counts: when Y increases, the bed will move towards you.

If you find that an axis is backwards, it is simple to reverse its motor: just power down and then reverse the order of its wires into the controller, so, for example, [black, green, blue, red] goes to [red, blue, green, black]. Don’t forget to turn the power off before disconnecting and connecting wires.

Note: Melzis shipped before 16th May 2013 have the X axis direction inverted, so if you have a Huxley with MXL belt, shipped before this date, you will either need to update your firmware or swap the wires as described above.

Endstops and homing The endstops are only checked during homing.

To check they are functioning correctly, send the command: M119 You should get the response SENDING:M119 x_min:L y_min:L z_min:L Test each endstop by holding down the microswitch and send the command again.

With the X microswitch pressed, you should see: SENDING:M119 x_min:H y_min:L z_min:L The X axis endstop is ‘H’ for High, and is functioning correctly. Release the microswitch, and test the others.

Then test the endstops with each axis. Send a homing command for the X and Y axes in turn. Either press the ‘X’ and ‘Y’ homing button in Pronterface (above the ‘dial’ on the left of the Pronterface window), or use the homing command: for example G28 X0 As soon as you press ‘Send’ and the axis begins to move, activate the relevant limit switch to halt movement of the axis. If activating the switch does not halt your axis, check your wiring (Huxley here or Mendel here). Then try each axis again, allowing the carriage to move until it hits the microswitch. Adjust the position or angle of the endstop until the carriage hits it in the right place.

(If the machine stops before reaching an endstop it may be because the endstop is being falsely triggered by interference from the stepper motor wires.)

For the Z axis, we need to check the Z endstop is high enough on the Z smooth rod to trigger the switch without the head hitting your heatbed.

To do this, screw the Z endstop adjuster, which you installed during the Z axis assembly, until about 4mm projects below the X motor mount.

Slacken the h bracket that holds the Z endstop switch. Position the Z endstop switch quite high, then home the Z axis, by pressing the Z home button in Pronterface, or sending the command: G28 Z0 If the nozzle is going to hit the bed, press the microswitch. When you press it the first time, the nozzle will start moving back up. Release, and it will come back down again. Finally, press the microswitch again to stop movement. Move the endstop up and try homing again. You want the endstop adjusted so that when the adjuster screw hits it, the extruder nozzle is about 1mm above the glass. Tighten the h bracket.

Before homing all the axes at once, the heated bed needs to be roughly level, or the nozzle may hit, or even worse, drag across it. If you are concerned this may happen, turn the Z endstop adjuster so it projects a couple more mm below the X motor mount.

Finally, press the HOME ALL button and your machine will find its reference position at X0 Y0 Z0.

Commissioning | 49 Bed still not level?

Aignment Level the X axis You already did this during the construction of the Z axis, but check it again. Measure the distance between the top of the X end and the top (or bottom - but be consistent!) of the Z motor mount, at each side of the machine.

Adjust until the distance is equal, by turning one of the Z motors. (10.4 & 10.5)

Level the bed If you have a Mendel, level the bed with the glass clipped in place with the four foldback clips.

If you have a Huxley, level the aluminium plate.

One of the major differences between the standard pronterface and the eMAKER version is the way the machine is manually controlled.

You have five buttons which enable you to position the head above the four corners of the bed and over the centre. The Z axis can be moved in increments of 0.1mm, 1mm and 10mm. The E axis can be moved by the amount specified in the distance spin control.

The speed of manual moves can be specified in the spin controls above the manual move buttons.

To level the bed, move the head up such that you have at least the height of your measured object between the head and the bed. Then position the head in the centre and bring it down gradually until it is almost touching the object.

Press ‘Motors off’ in Pronterface (top left of Window). It is quickest to level the bed by moving the X and Y axis by hand, but the following can be done by using the buttons, or moving the axes directly, in Pronterface.

10.4 Leveling X axis

1. Move the X axis over to the left edge of the bed, with two bed height adjusters, and move the Y axis so that the nozzle is as close as possible to one of the adjusters, but still over the bed. Adjust the adjuster so that the nozzle just touches your measured object. Tighten the locknut under the bed, recheck the nozzle height.

2. Move the nozzle to as close as possible to the second adjuster on the same side. Adjust the adjuster so that nozzle touches your measured object. Tighten the locknut under the bed, recheck the nozzle height.

3. Move the Y axis, so the nozzle travels along the edge of bed, from corner to corner, checking the height is even. Adjust the adjusters as necessary.

4. Move the nozzle to the centre of the Y axis, and over to the other side of the bed in X, so it is near the single adjuster. Adjust the adjuster so that nozzle just touches your measured object. Tighten the locknut under the bed, recheck the nozzle height.

5. Move the Y axis, so the nozzle travels along the edge of bed, from corner to corner, checking the height is even.

You may need to repeat the above the first time you do it, if you run out of adjustment.

When you have finished, the nuts on the M5 screws should be completely tight against the bearing mounts so the bed won’t move in operation, except on the springs.

10.5 Leveling X axis

A number of other factors can affect getting the bed perfectly level. Usually, it is because the Y axis smooth rods are not level, so while one side of the bed is flat with the nozzle, the other side rises and falls. You will see this in step 5 above. check the following: Check the machine is sitting on a flat surface.

Wooden furniture, by and large, is not flat. But thick kitchen worktops are very flat.

Small alignment problems with the frame.

It’s worth doing the frame alignment list from here: http://reprappro.com/wiki/ index.php/RepRapPro_Tricolour_frame_ assembly#Aligning_the_frame.

Check that nothing is caught under one of the feet.

Check that the Y axis smooth rod clamps are evenly clamped.

If you still can’t get the bed quite level, you may need to place a shim under one vertex foot, like a folded piece of paper, to get the bed perfectly level. If the side of the bed with two adjusters is level, put it under one of the feet on the other side.

Distorted bed Unavoidably sometimes the aluminium heat spreader or glass is not quite flat; it is saddleshaped with two diagonal corners one or two tenths of a millimeter low, and the two other diagonal corners high. Of course, it is geometrically/algebraically impossible to correct for this by adjusting three screws to define a first-degree (i.e. a linear) plane - a saddle is a second- (or higher-) degree surface.

But it is easy to fold a little aluminium foil to act as a shim under the glass in one corner to make the glass planar. Then you can use the three screws to get things spot on. (10.6)

10.6 Level the bed

50 | Commissioning

10.6 Foil trick If you find yourself tempted to use the foil trick in more than one corner - don’t. Just use it in one corner then take the time to use the screws as above to correct for every other outof-level error.

If you have a Multi-Colour machine with multiple extruders, the offset should be set such that extruder 0 is over the corner of the bed.

You can also adjust the Z height using the M206 command. M206 Z<value> where <value> is the amount in millimeters by which you wish to adjust the Z height. If the first layer is too close to the bed, you need to effectively move the bed down, so <value> will be negative. If the nozzle is too far from the bed during the first layer, <value> should be positive to raise the bed. The maximum adjustment is +/-1.27mm.

Heaters Tick the monitor check box to report the temperatures of your heatbed and nozzle.

Ensure that the readings are similar to the ambient temperature of the room.

Set your Z height

Heatbed

With the head at Z0, the tip of the nozzle should be just touching the bed. To achieve this, follow the sequence: HOME ALL Send the following command: G1 Zz F200, where z=the height of your measured object.

CENTRE Check that the head is within 0.3mm of your object.

For Huxley, adjust the height of the Z axis endstop, or for Mendel rotate the adjustment screw, and repeat until your height is set.

Check by Homing Z over the centre. Move the nozzle up 0.1mm in Pronterface, and check that a piece of paper can just slide underneath.

It is no bad thing to be slightly lower and squash the first layer; it will help the filament stick to the bed. It’s better than being too high, at which point you may have difficulty getting filament to stick.

Command the heatbed to 45C (warm), tick the monitor checkbox and verify that the heatbed temperature reading rises and stabilises around 45C, and that the heatbed is actually warm.

Setting offsets Depending on the distance of the endstop switches to the bed, it may be necessary to offset the nozzle in order to print in the middle of the bed and use its full area. Home the X and Y axes, then check if the nozzle of the first extruder is over the corner of the bed by sending the command G1 X1 Y1 F9000. If this is not the case, large prints will fail because they will not be on the bed. Set the offsets by using the command M206 X<value> Y<value>.

For example, with M206 X-40 Y-10, you offset the X carriage from the X endstop by 40mm, and the bed 10mm from the Y endstop. The M206 offset needs to be set with NEGATIVE numbers; like saying ‘when X=0, the endstop is -40 from here’. Follow all M206 commands with M500, to store the setting in the EEPROM, so your printer will remember this setting even if you remove power.

Hot end N.B. Some RepRapPro Huxley kits shipped with a Melzi controller between August 2012 and the first week of October 2012 have an error in the firmware. Please see this forum topic for a solution http://forums.reprap.org/ read.php?214,123839,159857#msg-159857 Check that the hot end fan is running. This needs to be on ALL THE TIME there is power to the printer - it should be connected directly to the 12V power input on the Melzi. It is part of the design of the hot end that the top part of it is continuously cooled, and the extruder will work extremely poorly, or not at all, if it is not cooled.

If it is not running, check the connections, power, and the fan polarity.

Command the nozzle to 100C and watch the temperature rise, overshoot and eventually settle around 100C. Keep an eye on the nozzle during this test. If you see lots of smoke come out of the hot end, turn off the heater and check your wiring. You may have a short on the heater wires, or to the heater block, or there may be some contamination around the heater block. Check that you used the correct, clear, ptfe heatshrink on the thermistor, not black heatshrink.

Repeat the test with a target temperature of 200C. The nozzle should reach the target temperature in about 1 minute or less and settle within a couple of degrees of 200C. Some smell of oil burning off is not unusual it’s the oil from machining the parts - but should dissipate after a minute.

Extruder Once you have verified the nozzle behaves as expected, you can carry out a test extrusion by hand. Pull the printed tongue out of the extruder block, and remove the brass bowden start piece from the extruder block. Feed some PLA into the tube until it reaches the nozzle (beware of the filament snagging on the short piece of PTFE tube inside the barrel).

Command the nozzle to 205C, and once it has reached and settled there, push the filament through and watch it extrude. The extrusion should be maintained with a steady but not excessive force.

Pull out the filament and reassemble the bowden tube for a test of the extruder drive mechanism. This time, click on MOTORS OFF or send an M84 command, and rotate the gears whilst manually feeding some PLA filament in through the extruder drive mechanism. Repeat the extrusion test, this time by manually rotating the large gear slowly.

Finally, try extruding material by commanding the E axis. In Pronterface, next to the ‘Extrude’ button in the bottom left of the window, set 5mm.

Underneath, next to the ‘Reverse’ button, set the speed; 200mm/min is a good speed for an 0.5mm nozzle (which is the standard Huxley and Mendel size); 80 mm/min is good for an 0.3mm nozzle. Press the ‘Extrude’ button to extrude some filament. Once you’re happy everything is working, turn the hot end heater and heated bed to ‘Off’.

Chapter 11: Printing Contents Preparing the bed surface 52 Cleaning 52 Settings 52 Preparing a file to print 52 Required software 52 Profiles 53 Using Pronterface and Slic3r 53

Starting a print Other useful software and links Your first print Tuning your printer Print another RepRap Profiles Changing filament

53 53 53 54 54 54 54

52 | Printing Preparing the bed surface Some people are lucky, and are able to print directly onto the aluminium (for Huxley) or glass (for Mendel) bed surface, and the PLA sticks. Try it first, it may work for you.

However, most people are not so lucky, and the sticking degrades over time, or different PLA has different properties and won’t stick.

We provide a roll of Kapton tape with our kits, and PLA sticks very well to it. It can be applied to the bed surface in strips - try to keep the air bubbles out, and put the strips as close together as possible, but not overlapping. Only apply one layer. Kapton is durable: we use it in the production of kits, and will last at least a couple of months of 24/7 printing. Usually it peels up before the PLA won’t stick to it.

Blue painter’s tape can also be used. PLA doesn’t stick as strongly to it, and the surface isn’t as flat or durable as Kapton, but it is more widely available, and often in wider widths.

Cleaning The bed surface needs to be completely free of all oil and grease (including finger marks), otherwise your prints won’t stick to it. We have found that the best stuff for cleaning the bed is cheap, Acetone-based, nail polish remover.

Check the ingredients before you buy - the expensive ones have lanolin or other greasy materials in, which would obviously be bad for this application. The cheap ones just have acetone ((CH3)2CO), a little water, and maybe a tiny amount of glycerine and a compound called bittrex (which is supposed to stop you drinking the stuff...); these work really well.

Wipe the bed surface thoroughly with a clean tissue dampened (but not soaked) in nail varnish remover.

You shouldn’t need to clean the bed after every print, but doing it regularly will mean fewer failed prints.

Other products that also work include Isopropyl Alcohol, White Methylated Spirits, White Vinegar. All of these are acidic, and dissolve oil and grease before evaporating. Don’t use Windex/Windowlene or polish; they often have a non-stick component!

Heatbed 57C ABS printing temperatures: Hot end 240C, Heatbed 110C For extra notes on ABS printing, see our ABS troubleshooting page here

Preparing a file to print Your 3D model will need to be processed into a format which the printer understands. This is known as a GCode file (machine movement commands are GCodes, [see this reference], and are common in the CNC world).

Required software NOTE: The current version of the Slic3r software available from the Slic3r website is version 1.0.0RC1, which has only recently been released. We are currently testing this, as it looks and acts differently. For the moment, download and use Slic3r version 0.9.10b. This is available from the same download location.

Windows If you are using Windows and downloaded the pre-compiled version of our software from Github in this step in ‘Commissioning’, Slic3r will already be where it should be, and Pronterface configured to use it. Jump to the “Profiles” section below.

Note: The version of Slic3r that is bundled with Pronterface is 64-bit. If you are using Windows XP 32-bit, Windows Vista 32-bit or Windows 7 32-bit, you will need to download the 32-bit version of Slic3r from here.

Mac, Linux and Windows ‘source’ installations Before you can process a 3D model, you will need to install a slicing tool and tell Pronterface where to find it. Slic3r is recommended to get you started printing with your RepRap machine.

This is available here. Click on the version for your operating system, and download the relevant compressed archive. Extract it into your Software folder, the one that contains pronterface.py.

In Pronterface, click on Settings | Options and check that slicecommand and sliceoptscommand point to the location of your slicing tool. You may be able to use relative paths, that is with a ‘.’ in front, but you may need to use the full path. This will depend on where you have put the ‘Software’ folder. For example, these may be: Windows slicecommand: ./Slic3r/slic3r.exe $s --output $o sliceoptscommand: ./Slic3r/slic3r.exe Mac slicecommand: /Applications/Software/Slic3r. app/Contents/MacOS/slic3r $s --output $o sliceoptscommand: /Applications/Software/ Slic3r.app/Contents/MacOS/slic3r Linux slicecommand: home/[USERNAME]/Software/ Slic3r/bin/slic3r $s --output $o sliceoptscommand: home/[USERNAME]/ Slic3r/bin/slic3r If you put the Slic3r directory somewhere else, you will need to change the path for the above commands to point at it. You can usually see the path to the file by right clicking the Slic3r application and ‘get info’.

Settings RepRapPro 3D printers are being sold as a complete printing solution, as such the RepRapPro host software comes with pretuned print settings for PLA and ABS filament.

We encourage people to play with and put forward improvements to the print settings, but would advise starting with the provided print profiles and working from there.

Some basic settings you may need to know: Standard nozzle size - 0.5mm (0.3mm available as an option) PLA printing temperatures: Hot end 200C,

11.1 Slic3r

Printing | 53 Profiles

Starting a print

Other useful software and links

Now get our pre-configured profiles, from https://github.com/reprappro/profiles Download and extract the zip into your Software folder (the one that contains pronterface.py), then point Pronterface’s sliceconfig option to it using the Settings | Options menu: sliceconfig: ./profiles-master/ Again, your path may be different. If you open Slic3r independently of Pronterface, it won’t find these profiles. Instead, it creates a hidden folder in your ‘home’ folder called ‘.Slic3r’ for profiles. You can move or copy the profiles into this folder if you wish. If you move them, change the sliceconfig path in Pronterface’s Settings | Options to point at the ‘.Slic3r’ folder.

To begin a print, you need to select the file you wish to print. You can print an stl file (as above), or load a gcode file you created previously.

If you are printing direct from USB, click the ‘Load file’ button to select the file, followed by the ‘Print’ button. If you have copied a gcode file to the SD card, select ‘SD Print’ from the ‘SD’ button, then select the file you want to print and click ‘Okay’.

Sometimes you get an stl file that doesn’t slice very well, or has holes in it, or other issues.

Slic3r will often tell you if this is the case, and try to repair the file. You can check the gcode Slic3r has produced looks correct by clicking on on the gcode preview window (the yellow area) in Pronterface, and moving up and down through the layers in a 2D view. If you want a 3D view of the gcode, there are many options; you can upload the gcode to http://gcode.ws/ or use one of the many gcode visualisation programs.

Sometimes the stl model does need repair. The easiest thing to do is to upload the file to http:// cloud.netfabb.com/ which will automatically repair the file for you. Alternatively you can download Netfabb Studio Basic from http://www.netfabb.com/downloadcenter. php?basic=1 which lets you manipulate the stl file. There are plenty of tutorials for using this on the internet.

Using Pronterface and Slic3r You should select a suitable profile for your machine, by navigating to the Settings | Slicing Settings menu option in Pronterface.

This will open the Slic3r software as shown below. Select profiles from the drop-down boxes along the lower part of the screen. The default configuration is a Huxley with a 0.5mm nozzle, using PLA filament. Close the window once you have set the profiles.

The 3D model will need to be in the STL file format. Pronterface can load either an STL 3D model or a pre-processed GCode file. Click on ‘Load file’ and select an STL file to process.

You will see progress of this process in the log window, and it will create a GCode file in the same folder as the STL file. You can re-use the same GCode file whenever you want.

Once complete, the log will indicate how much filament will be used to print the model. You can then either print direct from USB (your .gcode file will have been automatically loaded) or copy the GCode file to the MicroSD card in the machine.

It is recommended to print from the MicroSD, for a number of reasons. When printing from USB, the print can be adversely affected by the host PC giving the printer a low priority over other running applications, slowing down the stream of commands. Also, the USB connection appears to be quite sensitive to AC noise on the power cable to the host PC. To print from the SD card, copy the gcode file that you created in Pronterface to the card.

This can be done through the printer interface with the SD card still in the machine, but it is much quicker to insert the card into the host PC and copy the file. When you reinsert the SD card into the Melzi, the board will reset communication with the host computer; this is normal behaviour. Simply reconnect to the printer by clicking ‘Port’ button in Pronterface, and select the new port that appears, then ‘Connect’.

Once the print starts, the machine will go through the following startup routine: 1. The printer moves all 3 motion axes in a negative direction to find X, Y, and Z zero.

2. The nozzle is heated to the relevant extrusion temperature.

3. Once extrusion temperature has been reached, the machine will print an outline before printing the component(s) to ensure the melt chamber behind the nozzle is primed.

When not required to move, the Z motors are de-activated. This can be a useful feature as it allows the Z height to be tweaked and the X axis to be levelled whilst the outline is being printed.

Simply rotate the Z couplings by hand to get a good first layer (filament slightly squished). If you have moved the two couplings in unison to adjust the Z height, you will need to adjust the Z offset in the firmware before the next print, otherwise you will end up having to tweak the Z height manually at the start of each print.

11.2 Select a file

Your first print A good first print is one of the frame vertices from your machine: This is chunky enough to make a thorough test, and has some interesting features like horizontal holes, which require the machine to print on thin air (which it will do as long as the gap isn’t too big).

The file for this is on the RepRapPro Github repository here (right mouse click and select “Save link as”): https://github.com/reprappro/ Mendel/raw/master/Print-mendel/IndividualSTLs/frame-vertex-2off.stl.

(The source OpenSCAD model is here if you want that: https://github.com/reprappro/Mendel/raw/ master/Openscad/frame-vertex-readme.scad.)

Save the .stl file, load it up and print it!

11.3 First print

54 | Printing Tuning your printer The print profiles are tuned based on an assumption as to how much plastic is fed into the extruder for a given number of steps of the extruder drive motor. A critical parameter affecting the quality of the prints is how accurately the slicer knows the volume of plastic it is feeding into the extruder. In practice, this will vary slightly between machines. This is due primarily to the actual filament diameter, and to variations in the effective diameter of the hobbed stud.

The filament diameter should be measured and the value entered under the slicer’s Filament tab.

The E steps/mm setting can be adjusted without uploading new firmware, using M92 Ee, where e is the new E steps/mm value. By default the firmware has this set to 660. When this value is tuned, the top surface fill will have virtually no gaps between lines of filament, and no extra plastic at the ends of the lines. To check and adjust it do the following: 1. With the machine off remove the tongue from the extruder drive; 2. Wind filament through by turning the gear by hand; the end of the PTFE tube will come out of the drive; 3. Wind through about 50mm of filament and cut it with sharp sidecutters about 5mm downstream of the drive;

11.4 E steps/mm set too low

11.5 Test piece

4. Carefully mark where the stub of filament is flush with the drive exit with a fine felt-tipped pen; 5. Turn on the machine, send it an M302 command (allows for cold extrusion), and extrude 100mm of filament; 6. Mark again with the felt-tipped pen; 7. Extrude another 10mm and cut off your measured sample; 8. If the sample is L mm long and your current steps/mm is e, then change e to be e*100/L; (using M92 Ee, where e is the new E steps/mm value, eg M92 E650) 9. Send G92 E0 to reset the extruder zero point; without this, the next movement will be the incorrect distance!

10. Run the test again to check you now get 100mm; 11. To make the change permanent send an M500 command to store the values in EEPROM 12. Heat the hot end up to temperature; 13. Push a little filament through by hand from the 50mm you left sticking out, then pull the filament out to leave the path free; 14. Reload the machine in the usual way.

If you are making this adjustment for a Tricolour Mendel, then also see Hint 3 here.

If the E steps/mm is set too low, a gap will separate the fill lines (11.4) A good test piece for this exercise is a 3mm high 30x30mm square. (11.5) Once you are happy with your E steps/mm value, you can edit your firmware as per these instructions. Please update your firmware even if you don’t need to change this setting; new versions come out regularly for fixing bugs (like the bug where an unplugged/failed thermistor means the heater goes to full power)!

Print another RepRap So can I print more RepRaps in my RepRap? Yes! Your RepRapPro printer has been designed to replicate - that’s what the Rep stands for.

Indeed, RepRaps are humanity’s first selfreplicating manufacturing machines.

Replicating the plastic parts for another RepRapPro is easy. You can then use them to make a new RepRap (maybe with your own experimental design changes). Or you could make the RepRap plastic parts for a friend. Or you could sell sets of RepRap plastic parts to other reprappers on eMakerShop or eBay. RepRap’s free GPL Licence means that you are completely at liberty to do all of these things.

Go to this wiki page to find out how to print one complete set of RepRapPro Mini Extruder plastic parts. A RepRapPro Tricolour Mendel requires three such extruders. RepRapPro Mono Mendel and Huxley both need only one.

Go to this wiki page to find out how to print a complete set of RepRapPro Huxley plastic parts.

Go to this wiki page to find out how to print a complete set of RepRapPro Mono / Tricolour plastic parts.

Profiles Printing with different plastic may require modified print profiles. Have a look at http:// reprap.org/wiki/RepRapPro_Huxley_print_ settings for details, and if your plastic isn’t listed, please add to the table once you have worked out the best settings.

Changing filament 1. Heat nozzle to operating temperature.

2. Extrude a little filament, like 10mm 3. Set temperature to 100C, send M302 command (which over-rides cold extrusion) 4. Wait for the temperature to drop to 100C, then reverse filament until it comes out of the extruder drive (about 380mm). You can do this at 600mm/min, or by hand if you wish.

5. This should pull out most of the filament, hopefully down to the nozzle.

6. Command M84 to turn the motors off. Feed the new filament in by hand.

7. Drive/feed the filament to just before the hot end.

8. Set temperature to operating temperature 9. Command the filament to extrude short lengths at 200mm/min until it squirts out of the nozzle. You may need to hold the bowden tube straight for the filament to go down into the hot end easily.