Steam bending problem

[Royce Meritt]

I made my first attempt at steam bending a few days ago but had a minor "issue".

First of all, my set-up:

I built a steam box of 3/4" plywood. Placed a metal gas can on an electric hot plate. Attached a piece of 3/4" ID vinyl tubing to the gas can and ran that to my steam box.

Now the "issue"...

Once the water started boiling it seemed to produce a good amount of steam but from time to time seemed like the steam stopped going into the steam box. The vinyl tubing became VERY warm and seemed to get a lot of condensation on the inside of the tubing. I think I was losing too much heat through the vinyl tubing and the steam was condensing back into a liquid before it reached the steam box.

Does that seem like a reasonable explaination or is there some other problem with my set up? Would insulating my vinyl tubing or using a different type of tubing help? ANy other thoughts?

Thanks.

[Jay Jolliffe]

The ones that I've used had a thick piece of black tubing from the top of the can to the bottom of the steam box. It wasn't to long. They used hose that was for the radiator in a car. Plastic tubing is to thin......

[Bill Bukovec]

I agree with Jay. Try a bigger hose. The shorter the better.

Bill

[Steve Kohn]

I'm no expert but don't you also need to have an outlet for the steam on the box?

[alex grams]

Make sure you have a good seal on your steam generator, you need the motive pressure of the steam being generated to help propel it into your steam-box.

Also, dips in your hose will cause a p-trap effect which will collect water and provide additional resistance to the steam flowing up the hose. Try your best to avoid sags in the line. When steam flows through a sag full of water, it will cool the steam as it goes through, causing more condensate and thus only making the situation worse.

I think a 3/4" hose is fine. I actually used a smaller hose (I think 3/8" ID?) A smaller hose will give you more resistance, but also create a higher flow speed in the line, which will help push through any condensation and help prevent condensate buildup in the hose.

http://i613.photobucket.com/albums/tt220/alexgrams/KitchenTableChairs051.jpg

[Jay Jolliffe]

Forgot to say that the box should be at a slight incline & have a drain hole to let the condensation that builds up out.

[Bob Glenn]

You need to have a hole in your steam box to vent the box and give spent steam a place to escape. Kinda like having a heating vent in a room without return air to the furnace, no place for the warm air to go. I have placed the holes in my steam box as far away from the steam entrance as possible. It also helps to support the wood you are going to bend on dowels so as to get good heat penetration throughout the wood. Good luck.