Experiencing wood fabrication - Steam Wood and bending

Charmian Lui Nelson Nicoloso Spencer Miller Andrew Anderson

S T E A M

B E N D I N G

1 0 1

+ D E S I G N

CONCEPT The concept of this project was to develop architectural elements which could be used to create a spatially deďŹ ninitive assemb l y. I d e a t i o n ex p l o r e d a series of options from conic spirals to simple bulges, to fully freeform bend/twist combinations.

S T E A M

B E N D I N G

JOINTS

1 0 1

+ D E S I G N

SPANS

CONCEPT SELECTION With a limit of two bend types, selection of the bent elements to be developed focused on one connective element or joint, and one spanning, spatially deďŹ nitive element. The joint would necessarily allow for connection at different directions, and the span would need to behave as a surface.

S T E A M

B E N D I N G

1 0 1

+ D E S I G N

JOINT DESIGN The design of the joints is intended to provide regular and equal directional transference. The ability of bent wood to redirect forces is being capitalized upon. Planarization of faces is desirable.

S T E A M

B E N D I N G

1 0 1

+ D E S I G N

The joint geometry is a pyramidal one, or one which tapers to a point from any regular polygon. Despite originaly thinking that the height of the geometry would be determined by t h e b e n d i t s e l f, i t t u r n s o u t that each face of the joint i s p l a n a r, a n d t h e h e i g h t o f the joint will be determined by a twist which will force the connection into a deep position. This means the joint is a bend with two twists.

BEND

JOINT GEOMETRY

TWISTS

S T E A M

B E N D I N G

1 0 1

+ D E S I G N

S PA N G E O M E T R Y The span geometry is a simple one, which uses a bulge to create a surface from a line. Each bulge adds to that before it, demanding more bend and having a longer length to reach the point of reconnection.

ANGLE FROM VERTICAL

RAILS

STEAM BENDING 101 + DEVELOPMENT

FREE PORTION OF BEND

JIG DESIGN - 120Ëš JOINT The original jig design for the joint type was set for the 120 degree angle joint, the joint with three legs.

The design for the jig was to set the legs at the correct angle, then twist them inwards to a speciďŹ c angle, which will imbue the joint with height. The jig needed a way to be secured to the working surface, and rails on which to position the bend. We decided to allow the wood to twist/bend through its curve naturall y.

120.0째

5/1

31

6 12 0.0 12 째 9/1 6

STEAM BENDING 101 + DEVELOPMENT

12 째 0 .

0

2

18

39.6째

18

3

J I G T E M P L AT E - 1 2 0 ˚ J O I N T The template for the jig gives a at base for connection to the workbench, and doubly reinforced bending plates to give space for clamps to connect, while still providing the necessary strength.

The angle for the twists is 39.6 degrees, a number pulled from the digital model

STEAM BENDING 101 + DEVELOPMENT

JIG ISSUES - 120Ëš JOINT After completing the ďŹ rst joint, we evaluated issues with the bends which could be solved through the jig.

The biggest issue was the lack of depth in the joint, which necessitated an increase in angle of the plates. The other major issue was the lack of control point for the top of the bend which meant the legs were often uneven, as was the bend.

A d d i t i o n a l l y, t h e p r e c i s i o n necessitated by these joints made the springback issue very problematic.

This was not an issue which could be solved with the jig, and had more to do with the drying methods.

STEAM BENDING 101 + DEVELOPMENT

FINAL JIG - 120Ëš JOINT The ďŹ nal jig for the 120 degree joint utilized platforms that were angled from straight, to allow a steeper angle and impart more depth to the joint. A guide was also included at the midpoint to allow us to control the joint a little b e t t e r. A d d i t i o n a l r e i n forcement was added, in order to allow us to bend thicker pieces.

STEAM BENDING 101 + DEVELOPMENT

FINAL JIG - 90˚ JOINT The 90 degree jig had already included many of the innovations we included in the final 120 degree jig. We also used additional reinforcement and a middle bar on this jig.

STEAM BENDING 101 + DEVELOPMENT

J I G D E S I G N - T Y P I C A L S PA N The jig for the span pieces is simply a series of 2x4’s inserted between each slat, with a notch to hold the slats together at the end. The boards were sliced at one half inch intervals from one end, left connected on the o t h e r. T h i s a l l o w e d t h e m to shift past each other depending on their length.

STEAM BENDING 101 + DEVELOPMENT

4

3

2

1

5

BEND PROCESS - JOINTS The bend process for the joints was to attach one leg to the jig, twist the piece, bend the piece, and twist the piece down to the other platform.

STEAM BENDING 101 + DEVELOPMENT

BEND ISSUES - JOINTS The issue with the bending process was the lack of control through the bend.

By attaching one leg first, the location of the twist and bend was not consistent throughout the s e r i e s . A d d i t i o n a l l y, fi n d ing the centerpoint of the piece to make the legs even was not possible.

F i n a l l y, t h e s t r a p w a s v e r y difficult to use with this g e o m e t r y.

STEAM BENDING 101 + DEVELOPMENT

6 43 1 2 5

B E N D P R O C E S S - S PA N S The process for bending spans was relatively simple, although some trial and error was required to ďŹ gure out that at the least, the notched block must be the last point secured (so branches can slide past each other). Beginning in the middle is also important as each branch builds upon the previous distance.

STEAM BENDING 101 + PROCESSING

PROCESSING - DRYING The drying process for joints was particularly important, as there is some degree of precision required for these pieces.

We used the natural desire of the joints to form their shapes to put pressure on each of the other legs to dry in shape. The spans dried with their jigs in place, and had no issues with springback.

STEAM BENDING 101 + PROCESSING

PROCESSING - SANDING Sanding the bent wood removes most of the marks of bending, which typically include a kind of wrinkling that occurs in areas with compression. The wet wood also has a grungy kind of look, which can be smoothed out and brightened by sanding.

STEAM BENDING 101 + PROCESSING

PROCESSING - JOINING The joinery demands for this piece require disass e m b l y, w h i c h r e r o u t e d u s from our original design which would have used glue and dowels to create a seemless transition.

Instead we used a template and countersank the bolts into the joints to try to minimize the appeara n c e o f t h e j o i n e r y.

STEAM BENDING 101 + PROCESSING

S PA N P R O C E S S I N G The processing of spans is glueing the split end t o g e t h e r. O n c e s a n d e d , only the discontinuity in the grain gives away the fact that there was ever a cut. Sanding and drilling to the template ďŹ nalize the piece.

STEAM BENDING 101 + CONCLUSION

M AT E R I A L L E A R N I N G Some majore takeaways from this experience are: +Precision with steambending requires heavy investment in jig technolog y. +Control is the most important aspect of the bending process +Rushing the process will negate its effects +Simple moves can create powerful affects. +Poor material selection can be overcome by longer s t e a m t i m e s , c o n v e r s e l y, good material selection can be negated by short steam times. + J I G D E S I G N , J I G DESIGN, JIG DESIGN, JIG DESIGN

STEAM BENDING 101 + CONCLUSION

NEXT STEPS To f u r t h e r d e v e l o p t h e learning shown here, better jigs should be used to better control the bends. A horizontal jig (which uses the table to stabilize the bend) would be ideal, and one with m u c h m o r e c o n t r o l allowed. A jig which allows for drying in place would also be ideal. Figuring out the exact angle to height ratio would be another important piece of informat i o n t o g a t h e r, i n o r d e r t o increase precision on these joints.

The span pieces also show great promise and could be really interesting, especially in more freeform m a n n e r, o r i n a m o r e d e n s e format. Exploration with these types is not geometrically or processually challenging, but holds a lot of promise for some very interesting elements.

Materials Design Spring 2018 NSA+D Inst. Philipp Bosshart