Friday, April 6, 2007

My Kiln

To folks unfamiliar with working green wood, this must look absurd! My kiln is nothing but an oversized E-Z bake oven. I built a simple table and lined the lower portion with 1" reflective celotex (the top holds my grinder and sharpening stones). I have three light fixtures inside and depending on the time of year, use various wattages to keep the temperature at 140 degrees at the TOP of the chamber (where I dry leg tenons). I adhere to the idea that the maximum temperature that the wood should experience is 140 degrees to avoid scorching it. The chamber is just large enough to fit my bending forms. There are probably better designed rigs out there, and I've been promising myself a redesign some day but this one works fine for me. At the top of the chamber are 5 holes that I slip my leg tenons into to selectively dry them. The fifth hole ensures that the moisture laden air has an exit when the other 4 are plugged with legs. When there are no legs in the top, I cover the opening to help contain the heat, once again, leaving a small gap for egress of air. Fire safety is a great concern and should be considered in constructing a kiln. I have isolated the light fixtures from direct contact with the celotex with bakelite sheets. Common sense should guide you, look for any scorching that may reveal dangerous conditions. I have used my kiln for 6 years (running almost continuously) with no problems. Experimentation is the key to learning to use your kiln, perhaps starting pieces drying with only one bulb on etc... Wood will always seek to equalize its moisture with the air around it. Our sense of mystery about this can be quickly dispelled by taking one piece from dead green to bone dry in just a few days. Once you give it a try, a whole new world of possibilities will open up to you.

1 comment:

greg said...

I've been meaning to get around to making a kiln one of these days. So far I have been able to get by with various work-arounds. My favorite is to leave a set of spindles on the dashboard of the car when it's parked in the summer. If you want to get scientific, weigh the bundle and take them out when it stops losing weight.

I've also made due leaving parts in proximity to radiators, furnaces or wood stoves, and then there's the pot of sand on a hot plate set "low" for sticking the top taper part of legs into.

Work-arounds are fine for someone making a handful or so of chairs a year, but probably someone making a living at it should consider a kiln more sooner than later.