Steam Bending Wood - Box material?

[Prashun Patel]

I have been using a plywood steam box for a couple years. It has delaminated over time.

i have to make a new one. I hear many people use PVC. I tried some scrap sewer pipe (schedule 20). It melted quicker than butter in a frying pan.

I've heard many people use 40 or 80 or abs pipe to good effect as steam chambers. However, wouldn't they all be pretty susceptible to melting?

All of their temperature ratings are below 200 deg.

I'd like not to have to make another wood box. Pipes of different sizes would be cheaper and more versatile for my purposes.

Have any of you used schedule 40 or 80 pvc with a steam generator?

[Bradley Gray]

No experience with PVC pipe but I did try to use blue sheet foam to insulate one of my wood boxes and it was an epic failure. The foam swelled and distorted - didn't even survive the first run.

I did line one box with alum. coil stock and that is still working great.

The silicone flap seals from Conservation Tech also hold up really well.

[derek labian]

I was considering building a new steam bending box out of 6"/8" metal duct. I saw this somewhere not to long ago where the shelving was done with metal rods just drilled through the sides, and then metal caps at each end. I might use a nordfab duct to make it easy to have variable length and easier for storage.

Here's someone who did it with spiral duct:

[Alan Schwabacher]

I used foil-faced foam insulation board, held together with aluminum tape. All edges exposed to steam are sealed with the tape, but some outside seams are exposed so that when the box ends are removed it will all fold flat. It works fine and stores easily.

[Maurice Mcmurry]

I have used PVC and it does distort with the heat. I can't find the PVC version it looks like a Salvador Dali subject. Here are two very simple ones. Interestingly a 4 pound coffee can fits 6 inch stove pipe and a 1 pound can fits 4 inch.

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[Phil Mueller]

That’s interesting. I’ve used PVC numerous times and have had no issues. Here’s the pipe I used…just something from the big box store.

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[Bradley Gray]

A friend who once installed in-ground swimming pools talked about hooking PVC pipe to the tailpipe of their work truck to bend it.

[Maurice Mcmurry]

The less expensive, 3 ply, Cellular Core, SCH 40 DWV PVC (not for pressure) takes heat well. Trying to bend it by "cooking" does not work. There is also grey SCH 80 PVC. It is rated for higher temps and is amazingly tough.
Steaming vertically limits the lengths you can work with but you capture a lot of heat by being directly above the heat source.

Screen Shot 2022-10-10 at 6.16.31 PM.jpeg Cellular Core, it is sort of pre insulated

[Bruce Wrenn]

Support the PVC in a "V" shaped cradle made from plywood. When passing metal rods thru box to support wood, I recommend that you use a sleeve of PVC conduit to prevent staining of the wood (oak). DAMHIK, but I do.

[Prashun Patel]

The PVC Schedule 20 that I used collapsed so badly, the v shaped cradle wouldn't have helped. It was so bad, I couldn't imagine how 40 or even 80 could be impervious. Will try.

[Tim Janssen]

I use insulation foam board for my steambox:
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Has always worked fine for me!
Cheers,

Tim

[Brice Rogers]

The three ply pipe that Maurice McMurry mentioned makes sense. The inner liner may get soft but it won't deform because the outside layer is much cooler and stiff.

[Mel Fulks]

I think these “steamy “ reads should always mention that only air-dried wood is going to work well for steam bending .

[Maurice Mcmurry]

I sometimes boil kiln dried wood for bending. It usually ruins the appearance of the wood. Grain makes a big difference too. I bend with perfectly plain sawn and perfectly quarter sawn. Quarter sawn usually wants more heat than steam can provide.

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[Brad Rucker]

I use schedule 40 PVC pipe - 10 feet of 4" diameter. I cobbled up a support box of scrap plywood that sits under it and does two things:

o Angles the pipe down to the drain hole in one end
o Keeps it from distorting over time

Many bends done with this set up and I haven't had any issues.