PVC Steambox- Anyone built one?

[marlboro180]

Anybody ever build a steambox for a 15 ' long piece?

I have decided that my plans for a curved steel railing are not gonna work out, too many things in the house now to drag the welder and torches inside again.

So, I got the idea to do a curved wood railing ( guardrails and handrails), which will require a 12' piece, and two 15' pieces of maple. They will be fairly thick, in order to comply with the requirements of handrail cross sections as per code. Approx. 1 1/2 inches thick, minimum.

Currently I have on hand to build what I think I want :

some 4" schedule 40 PVC pipe, and fittings
plenty 'o copper pipe and fittings
empty 20# propane tank ( for the steam vessel)
500,000 BTU weed burner

I know the basic concept of steaming wood, but after looking all over the net, I have yet to find a good idea as to how to put together a decent one of this length, probably 16 feet overall. I am wondering if I am going to be able to get enough steam dispersion over the length of the piece:redface:.

Any thoughts?

Pics below is my crazy idea of a stairway which needs more work:redface:

 

[rockyrude]

Re: PVC Steambox- Anyone built one?

I think you have the basic idea , you run the steam into one end of the pipe and vent it slowly out the other end. You will need to support the wood off of the sides of the pipe to get complete coverage of the steam. A 20# tank won't be big enough, it probably holds 2-3 gal of water, to steam 16' will need closer to 15 gal. because you need to fill the pipe first and then keep it full for pretty close to an hour for a 1-1/2" piece. The fun begins when it's ready to bend, you need to work fast since it'll start to re-harden almost immediately. There is alot of info on steaming "on the net"
Also, insulate the beegebers out of the pipe to help keep the temp up.

 

[joed]

Re: PVC Steambox- Anyone built one?

I have never used PVC for steaming. I have used straight steel venting wrapped in newspaper to insulate it. I would be worried about the pvc getting soft and bending or collapsing when it heats up.

The actual setup I used was a T ftting with vent pipe out both ends. This way the steam could be applied in the center. Steam was applied by putting a tea kettle under the open T and letting it boil away.

 

[rbh]

Re: PVC Steambox- Anyone built one?

If the steaming turn out to be to much of a pain in the butt.
Finger joint the pieces together?????
OH, that would be a lot of work.

 

[geeco1]

Re: PVC Steambox- Anyone built one?

On the Glen-L website, there is an article about building a steam pipe like you are wanting. You may have to search for it as I don't remember exactly where it is at on the site. I think that it is in one of the news letters.

 

[marlboro180]

Re: PVC Steambox- Anyone built one?

Rocky- I have read that temp is the key to a good steam. Good point on the insulation.

Joed - many steamboxes seen on the net ( so it must be true) made of PVC. Longish ones tend to sag, so supports for a 17 footer are probably in order.

Rob, yeah, finger joints are a pain.... But may be necessary, but I would be more inclined to scarf join 'em.

Geeco, Found it on Glen-L, thanks. In the news section, shoptalk...., steambox.

http://www.glen-l.com/

Still gonna build something for a steambox , maybe it will work while I wait for my samples from these guys.http://www.flutedbeams.com/ Saw some video, called the maker, and I was impressed.

They made it into Woodenboat Magazine , must not be all bad...Their product is called Compwood, seems really intriguing. Cold bent wood.....hmmmmm.
Just ordered a maple sampler today , 2 bills to try it. And I am gonna see if it is the neatest thing since sliced bread too!

 

[Tim Frank]

Re: PVC Steambox- Anyone built one?

www.leevalley.com

 

[joed]

Re: PVC Steambox- Anyone built one?

The other option is laminating. Cut you 15' wood into 1/8" thick stips. Build a bending jig the shape you need. Apply proper marine glue and bend and clamp the strips to the shape required. Make it longer so it can be timmed to size.

Larger thicker wood can be difficult to bend. For sure you need to start with very straight grained wood. If you can get green fresh cut lumber it will work better as well for bending.