Thursday, October 3, 2013

Sledding Through the Curves

How do you make a perfectly fair curved surface out of solid wood that's 20" wide , 28" long, and almost 3" thick? That was the challenge of the latest project in the shop. The project is a pair of nightstands made of solid mahogany, and based on a Klismos-inspired stool I made last year. 

I know what you're saying .... go find a 20" capacity bandsaw and just cut the curves. Easier said than done, and then there would still be the challenge of building a jig to keep the slender blank perfectly perpendicular to the saw table - no easy feat. Ultimately, I decided to stick with the equipment I had, for convenience. Since I only have a 12" capacity bandsaw, and the premium pattern-grade Sapele I was using was only about 6-8" wide, the sides would have to be glued up in three pieces.

To strengthen the joints, I added dowels, which were positioned properly in the blank using a shop made drilling jig.

After the dowel holes were drilled, the outline of the side was cut using the bandsaw. The blanks were then glued up and set into a fairing jig. 

The fairing jig works with like the setup often used to flatten large slabs with a router. The sides of the lower part of the jig are the exact fair arc that describes the curve of the nightstand side. Riding across these is a sled, along which a trim router rides. As the sled moves along the curved rails a series of narrow flats is created.

The faired surface can then be sanded smooth, resulting in a fair curved nightstand side. 

Bandsawn blank (L), rough faired blank (R), and sanded fair side (bottom).

The faired sides can then get their joinery cut and the nightstands take shape - stay tuned....

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