Boat design

Steambox Boiler

Ive decided that winters just arent long enough. I had 3 big projects planned for this winter, and at this point, it looks like Ill be lucky to get two of them done. Ah, well. Its the human condition.

I had hoped to find a metal gas can for my steam box boiler, but could not find one locally (they are all plastic), and though they are available online, the price ($40-50) was more than I wanted to pay.

People also use pressure cookers, but they are pricy, unless you can find one at a garage sale. Helena and I sold our pressure cooker at a garage sale, not so long ago. Who ever thought Id need it?

Someone on the wooden boat forum mentioned using a paint can, and Home Depot has new paint cans for sale for under $5, so rather than wait for spring and garage sales, Ive decided to go with that for now. I can always upgrade it to a pressure cooker or whatever, when I find one in the wild, this summer.

The reason you want a pressure cooker or gas can or paint can is the boiler needs to be a closed vessel, so the steam doesnt leak out. You could use a spaghetti pot or equivalent, but then you need to figure out how to seal it and keep it sealed during the steaming process. A normal pot lid doesnt seal the pot sufficiently.

To make sure the paint can bottom can hold up to an hours boiling, at least, Im going to do a test boil. Ill also try to determine how much water is boiled per hour, by checking to see how much water is left after an hour.

But here are some pics of the basic set up.

First, you need some sort of flange to attach the hose to both the can and the box. A correspondent to this blog, Jono, tipped me off to this common plumbing fitting:

Flange & material for gasket

You also need to make a gasket to keep the system closed. My hardware store had a make your own gasket kit, with a piece of red rubber that you can cut to size with a pair of scissors.

Here is the lid, gasket, and flange ready for assembly.

lid, gasket, flange

And the whole boiler assembled, with hose clamped on.

Assembled boiler

The hose is about 1" inside diameter radiator hose that I bought at a local auto parts store. There is a 3/4" inside (approx. 1" outside) diameter nipple screwed into the flange and the hose is clamped to that.

Steam box buttoned up

I drilled a 1" hole in the bottom of the box, and affixed the same type of fitting to the bottom of the box, using wood screws.

Several correspondents warned me that my box would swell, jamming my cute little door shut, thus trapping my hickory inside and over cooking it.

To avert this tragedy, I opened up the dados that the door dropped into even more. Since a few people wrote to ask about my homemade router plane, I made a quick video, showing it in action.

Basically, what Ive done is move the blade so it cuts about 1/8" deeper than the original dado. The blade is adjusted by loosening the wing nut on the back. Ive already widened the width of the dado by about 1/4".



I do about 90% of the work in the first few seconds, then take another minute to get the corners sharp and clean. That seems a bit long to me, as I watch the video, but I was showing off for Helena!

Im still practicing with this great little tool, so imagine Ill be quicker and less fussy as time goes on.

The results are quite good!

Anyway, back to the boiler. I know that some will consider doing a test run a bit nerdy... after all, this isnt NASA doing a test burn on one of their rocket engines, but what can I say? Im a nerd at heart.

Rocket scientist at work

The results of an hours test burn are happily undramatic:

First, the can seemed unaffected by the hours boil. It certainly didnt melt down, and frankly, I dont see any damage whatsoever to it. I imagine it will be good for at least several boils, as long as you dont let it run dry.

Second, a gallon was more than enough water for an hour. There was about 1/3rd of a gallon left. If I needed to do a two hour steam, Id boil up another gallon in a kettle on the stove, and quickly refill my little boiler. I dont think it would take more than a minute to refill, which wouldnt have much effect on the steaming process.

Third, the boiler makes a huge amount of steam. You can see the plume in the background of the photo above. I think the 1" hose helps in this department. You dont want to do anything to impede the steam.

So, I do believe Im ready to do some steaming. The next step is to build the forms to bend the steamed wood around.


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