Building a steamer

Homemade steamers for bending wood in your shop. January 21, 2002

I would like to build a steamer for use in my shop. Does anyone have plans or suggestions?

Forum Responses
You can build a steam box out of 3/4 cdx any size you need. I used to t&g the edges together using high temperature silicone and screws, but the ply would delaminate before the seams would even begin to show ware, so now I just screw the butt edges together. For the boiler I use a propane shrimp cooker (a camp stove type) and a five gallon gas can (metal and gas free, of course) with a short rubber hose to connect the can to the box. Drill an escape hole (about 1/2 inch) in the opposite end of the box to let condensation drip out.

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 used one of those plastic covers that you slide over your deck post. I found a damaged one at the lumber yard and got it for $9. I used 1/2" copper pipe along the bottom of the post cover with holes drilled into it about 6" apart distribute the steam. There's a tee in the center of the pipe that drops through the bottom of the box to hook up the steam pipe. I flattened both ends of the copper pipe inside the box so the steam would only come out the holes along the pipe.

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!