How to Bend Wood – and Set it – in Just One Day - Popular Woodworking Magazine

How to Bend Wood – and Set it – in Just One Day

 In Chris Schwarz Blog, Woodworking Blogs

The cold-bend crest rail after only 16 hours of being bent.

Bending wood is great fun, but it can be frustrating when you need to work quickly (i.e. make a living at it). After you bend a piece of wood and clamp it to a form, you usually need to let it sit for several days to a couple weeks, depending on its thickness.

Recently we added a small kiln to our workshop that is made from hardboard, foil-covered insulation and a couple lightbulbs. It holds a temperature of about 110° to 125° with ease. And, it turns out, this dirt-simple kiln box is the trick to making bent parts in a hurry.

The kiln, built by Brendan Gaffney, in our shop.

The interior of the kiln – dead simple.

Right now I’m working on a chair with an unusual crest rail. After making a prototype in MDF, I started making the real parts in maple cold-bend hardwood from Pure Timber LLC. Like wood you bend in a steambox, this stuff has to reach about 7 percent moisture content before you can use it. (More details on drying the stuff here.)

The first crest rail took two weeks to reach 7 percent (good thing I was traveling during that time). When I made the second crest rail I put it in the new kiln. On a lark, I checked its moisture content after about 16 hours. It was 3.1 percent. I was shocked.

I took the crest out of the form and it held its shape perfectly.

This combination – cold-bend hardwood and the small kiln – has completely changed my workflow. Instead of planning jobs several weeks out, I can turn parts out overnight.

Though the cold-bend hardwood might seem expensive, it’s not as bad as you think after you factor in the fact that you have a failure rate of 0 percent when bending. No splits or ruptures, even with tight bends. (Well, that’s been my failure rate for the last several years.)

Cold-bend hardwood might not be right for you and your shop, but it’s worth running the numbers.

— Christopher Schwarz

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Showing 4 comments
  • AlanWS

    Does this work with steam-bent wood as well?

    • Christopher Schwarz
      Christopher Schwarz

      A kiln will always speed up the process. Steam-bent wood has a lot more moisture than cold-bend wood. So (in my experience), it takes about two or three days in the kiln to set the bend with steam-bent materials.

  • kc0dxh

    Sounds more like a time machine than a kiln.

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