D E C O 2 1 0 3
3d Modelling & Fabrication ASSESSMENT TWO - 3D MODEL
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& t he Space K a rrot rhino3d™ modelling PROCESS & ANNOTATIONS James Feng 4 4 0 2 8 4 4 0 8
rhino3d™ modelling PROCESS & ANNOTATIONS S c r e e n - s h o t s
Fig.1 Head + Body Basic forms were made from using commands _sphere (for head) and _rebuild; _points on/F10 (for body) then points manipulated using gumball to achieve desired effect.
Fig.2 Ears Ears were made in two parts: firstly a base curve was drawn then piped with variable radius, note the minimum radius was set at roughly 1.5mm taking into consideration the fabrication process that is to come. The rest of the ear pinna was created by _dupedge; _extrude (solid checked yes); the two parts were merged by _booleanunion; then the curvature created by using _bend. The ear was then duplicated by alt + drag using gumball then _mirror’ed across to the other side using Osnap on the sphere midpoint and dragging up while holding shift (front view).
Fig.3 Eye Bag /Socket By far the most ambitious/challenging part of the toy to model. First attempt was the intuitive way to _pipe a flat curve that was _project’ed onto the head sphere. The aim was then to use different radii in different areas and then use _pointson to _ points on to manipulate the geometry into bumps, wrinkles and folds. As seen in the screenshot on the left there is a problem with this approach, the loop self intersects and creates a mathematic paradox. Therefore it had a high probability of failing when undergoing boolean operations.
Fig.4 Mouth After the frustration subsided, the mouth was the next body examined. Since it is a deliberately minimal design that contributes to its expression, the solution was simple and elegant, base curves were drawn and _loft’ed to form a solid, this solid will be used to subtract mass form the head using either _boolean2objects or _booleandifference.
Fig.5 Boolean Union Test To make sure the modelling process will progress smoothly, constant checks were done on whether the forms will successfully be booleaned together, naked edgeds and non-manifold edges were checked for as well using Analyse > Edge Tools.
Fig.6 Eye Brows/Bag Cont. The bridge was created using the same process mentioned in Fig 1. Sphere rebuilt and bent. As mentioned before, the intersecting end was problematic and eventually will need to be addressed. The base curve was _trim’ed and _ piped. However manipulating points using gumball was ineffective as there are varied degrees of details required as different location of the pipe.
Fig.7 T_splines pipe After some research, it was decided that t-splines would be used to model complex details as it has a high level of control and interpolating option to achieve clean/smooth geometries. Piping then was done using t_splines tools as seen on the left.
Fig.8 T_splines Smooth Toggle Turn on and off _smoothtoggle, geometries can be manipulated by moving, rotating, scaling points, surfaces and edges oh these blocks to achieve a desired look. Individual groups of surfaces can also be _ subdivide’d to achieve more detail than other areas. This was used to create wrinkles on the eye bags.
head details & cleaning geometries S c r e e n - s h o t s
Fig.9 Backing up Mouth To allow the head to remain editable as a t-spline surface, boolean operations can not yet be performed, there for the mouth was backed up as a separate solid and the head _untrim’med to remain in the editable state.
Fig.10 T_splines Smooth Toggle The sphere head is converted to T_splines to introduce hints of underlying bone structures and to blend with the complex eye bag geometries.
Fig.11 Forehead Displacements Forehead details were introduced by selecting certain faces and pulling them up, note a symmetry was set so manipulations stay symmetrical.
Fig.12 Naked Edge Fix 2 naked edges were found at the poles of the head sphere after playing around with t-spline manipulations, two small spheres were created in place to be later _booleanunion’ed to rid the naked edges.
lower body modelling S c r e e n - s h o t s
Fig.13 Arms Using the t_splines pipe command a limb was created and manipulated into a desired limb form.
Fig.13 Feet Using the t_splines pipe command a limb was created and manipulated into a desired form. The heel and the indent curvature was the main focus
Fig.14 Feet Cont. Toes were added by distorting primitives, in this case cubes then _booleanunion’ed onto the structure.
Fig.15 Shrunken Wings To add detail to the back of the body, small wings were made by drawing a base curve; _planarsrf; click + drag using gumball on Y-axis to create second copy; drawing a cross section arc, then _sweep2 to create a curved edge. The surfaces were joined; scaled and bent using the respective commands to become a subtle bevel on the back.
Fig.16 Talons Talons were created in an almost identical manner, besides the small different of rotating the base planar surfaces and mirroring so the joint to the back is thicker (tapered form)
Analysis and potential problems S c r e e n - s h o t s
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Analysis 1. Inner ears have a slight overhang, may need to staighten ears. 2. Slight overhang in eyebag, may need to adjust overhang angle. 3. supports may be required for lower part of head. 4. talon tips may be too thin, thickening may be required. 5. Uncertainty in whether the resolution on printer would allow the wing bevels to show, if not beveling needs to be increased. 6. Piping on the outer ears may be under the limit and may result in uncessessful print, thickening may be required. 7. overhand on brow ridge and side eye ridge may need to be reduced, or overhang angles may need to be increased to minimise scaffold. Proceed to preview in Makerbot.
Preview (Initial) S c r e e n - s h o t s
Comment: Scaffolds are not the end of the world, however it is always a good idea to minimise their use, as ripping the plastic off damages the model to a small extent. In this preview there were too many scaffolds and it is best to reduce to ones that are absolutely necessary. Also, parts of the ear appear to be missing. This is likely caused by the pipe members being too thin. Steps to be taken: 1. Thicken out ear pipe members 2. Reduce scaffolding supports by reducing overhand of brow ridge; eye bag and inner ears
Fig.18 & 19 Close-ups of Makerbot Test < Incomplete ears
< Scaffolds supporting head
Fig.20 Draft Angles Test Although normally used for optimising for injection mould fabrication processes, Draft angles was used to give visual ideas on how to make changes to minimise scaffold structures.
REVISION S c r e e n - s h o t s
Fig.21 Head Tilt A simple solution was to tilt the entire head, including all the features associated with it, up 10 degrees.
Fig.22 Details Fix Eye bag was manipulated to the overhang lessen and the overhang (cantilever) angle exceeds 45 degrees. Inner ears were rotated to be more erect. Outer ears were significantly scaled up to increase member thickness. The resulting output for was analysed to check for bad objects; naked edges; non-manifold edges etc.
Fig.23 Makerbot Test v2. Very pleasing result considering most supports were eliminated. However, artefacts were apparent in the left hand face. It was at first thought to be a resolution problem but after testing it did not seem the case.
Re-test in makerbot preview S c r e e n - s h o t s
Fig.24, 25, 26 Makerbot Test v2.Cont. After some further trial and error and research it was concluded that this had some relationship with the direction of movement of the nozzle head. By orienting the file to face the back of the print platform these unpleasant artefacts were eliminated.
Fine Details add-on S c r e e n - s h o t s
Fig. 27, 28, 29 Final Touches Some final touches were added to the cheek and back of head area after seeing how well the preview of the belly button had come out. Small dimples in the form of spheres and there stumps in the form of cylinders were _booleanunionâ&#x20AC;&#x2122;ed into the head to add subtle surface details.
Fig.28, 29 Makerbot previews of these surface details
final print preview & internal structure analysis S c r e e n - s h o t s
Fig.30, 31,32 Makerbot previews at 25%, 50% and 75% respectively at 0.2mm standard print resolution. Internal structure sugguests the geometries are read correctly.
Proceed to print.