DIY Network

Bent-Laminate Lamp: Making a Bending Form From "Wood Works" episode WWK-512

	Though it looks as if it were sculpted from a single piece of wood, the S-shaped center-post for this contemporary lamp is made from TK laminated sheets of koa wood.
	The curved legs are made in a separate bending form and hand-sculpted to blend seamlessly with the center post.

In this episode of DIY Wood Works, host David Marks takes bent-lamination to new heights as he creates a contemporary lamp with curved wood legs and center-support. The body of the lamp is made from koa -- a spectacular Hawaiian hardwood that's similar to walnut but not quite as hard.

To make this contemporary lamp, thin pieces of koa wood are cut on a band saw, drum-sanded into thin laminates, then shaped in a two-sided bending form. The finished laminate is cut in half, and a channel for the electrical wiring is cut in the center of each piece using a plunge router. The wire for the lamp is threaded through a bent copper conduit, set in the channel, and the two halves are then glued back together to create a seamless piece. The legs that support the lamp are matching bent laminations created using a separate bending form. The legs are joined to the trunk of the lamp with scarf joints to create a branch-like form.

Materials:

Koa stock
MDF for templates
Poplar for mockup
ACX-grade plywood for bending form
Jig saw
Table router; flush-bearing bit
Pattern-maker's rasp
Flexible sanding strip
Clamps
Yellow woodworker's glue
Compass
Straight-edge
Carpenter's pencil

Safety glasses or goggles

Safety Alert: Always wear safety goggles or safety glasses when
working with wood, power-tools, saws, drills, routers, etc.

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Figure A

Making the Bending Form

• To begin this project, we created a prototype for the design from inexpensive poplar (figure A). This helped in developing the overall dimensions, the curves and the spacing of the legs.

• Once the prototype was done, it was used to create a template for the curved center-post from 1/8-inch MDF. The curved template is then used to create the layout for the bending form that will later be used to bend the laminate strips of koa wood.
  
  
• Place the curved template on a sheet of 3/4-inch MDF and trace the outline of one side of the template (figure B).

• Using a compass, trace the opposing side of the curve. The point of the compass rides along the edge of the template while the pencil is set at a 1/8-inch spacing (figure C). (The1/8-inch setting provides additional room for a layer of cork that will be added later.)

  Figure B

  Figure C

  
  

  	Figure D
  	Figure E
  	Figure F
  	Figure G
  	Figure H

  
  

• Use a jig saw to rough-cut both sides of the master-template for the bending form (figure D).

• Use a pattern-maker's rasp and a flexible sanding strip to smooth the curve of the MDF template.

• For the form itself, use ACX-grade plywood. This affordable grade of plywood is strong and has one sanded side. The extreme curve of the design is a challenge for bending. The ACX-grade plywood will hold up well under the pressure whereas MDF (often used in bending forms) would probably break.

• Place the two sections of the master template onto the plywood sheet and trace the shape onto the sheet of plywood (figure E).

• Use the jig saw to cut out the shape roughly to size.

• Flush-trim the edges of the plywood smooth at the router table using a flush-trim bit that references off of the master template (figure F).

• Perform the same steps on separate plywood sheets two more times, then secure the pieces of plywood together with screws to create a bending form that is 2 inches thick (figure G).

• Most bending forms apply pressure in only one direction. Because of the extreme curve of our lamp, however, we need a way to apply pressure in multiple directions simultaneously. For that reason, one side of our bending form is cut into four separate sections. This will help provide even pressure, and reduce the chances that the laminates will crack. In order to facilitate proper positioning of the clamps during the bending process, notches and holes are cut into the form as shown (figure H).

• Add a 1/8-inch layer of cork along the leading edge of the curve to compensate for any variables that could create gaps. Also, seal both of the edges with clear-plastic tape to prevent to prevent glue from sticking to the form.

• Finally, you'll need a reference point to keep the laminates in alignment. Make a mark at the center-point of the form on both sides.

In the segment that follows, the laminates for the center-post are cut, glued and placed in the bending form.

RESOURCES :

Woodworking Techniques: Best Methods for Building Furniture from Fine Woodworking
Author: Editors of Fine Woodworking magazine
Publisher: Taunton Press
ISBN: 1561583456

David Marks Website
David Marks, DIY's Wood Works host, is a master woodworker. For more information on cut sizes and project details, please contact him via his Website at www.djmarks.com

Fine Woodworking
A magazine devoted to high-quality craftsmanship in woodworking.
The Taunton Press Inc.
Website: www.taunton.com