Building a steamer
The one I made and use was for steaming a few Windsor chair parts at a time, so it's not very large. A piece of 4 inch PVC about five feet long. A solid cap on one end and a threaded cap on the other. Don't screw the threaded one in very far or you won't get it off when you try to get the pieces out. I drilled through to put 3 sections of 1/2 inch dowel across the tube. In effect, to divide it so the pieces to be steamed wouldn't be laying in the bottom on the water.
I use a wallpaper steamer from the rental shop to provide the steam. The hose from the steamer is fit tight into a hole on the bottom of the tube about midway in its length. The tube is nearly horizontal but tips slightly to the end with the screw cap. There is a drain hole on the underside close to the screw cap end. The whole PVC needs to be supported so that it doesn't sag too much when you are using it. Say about every 18 inches.
I haven't used it for more than eight pieces of wood at a time, as that's about all I can cram in on top of the cross pieces and hope they all get sufficient heat and moisture.
We've started using 1 1/2" foil faced foam board for our steam boxes. The stuff is cheap, cuts with a razor knife and can be held together with a few galvanized box nails pushed into the edges every 6" or so. The boxes come up to temperature amazingly quickly... much faster than my old wood boxes wrapped in Styrofoam.
If you will steam wood for a severe bend, I suggest that you first dry it to about 25% MC--no lower--and then steam it. For milder bends, start at about 15% MC. Steaming is to add heat, thereby softening the wood. It must be done at a high humidity to prevent drying the wood, especially the wood fibers at the surface where stresses are the greatest. Excessive heating will permanently weaken the wood fibers.
Gene Wengert, forum technical advisor
I just bought a video on steam bending put out by Tauton Press. Packed with information.
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Comment from contributor A:
I then drilled holes into the post cover about 1" off the bottom and drove some 3/16" brass rods through (horizontally just above the copper pipe) at 6" intervals so the wood to be steamed can sit on the top of those rods.
I have an LP turkey fryer that I use for the burner. I took an old 20# LP tank (EMPTY) and took the top off of it and filled it with water to make sure all the gas was gone. Then I put a 3/4" copper threaded adapter in the hole and soldered a pipe a couple of inches long into the adapter. I then soldered a tee at the end of the 2" pipe. Part of the tee hooks up to the hose for the steamer box and the other part sticks straight up with a threaded cap on it so I can put water in without taking the whole thing apart. Make sure it's cool before putting more water in!
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