Steam Bending The Crosstrees


A client recently asked me to bend some oak for the crosstrees at the top of his mast. His boat is a 34' Atkins double ender.

The piece was only 8 feet long and a full 2 inch by 4 inch white oak board . There was not a lot of leverage available. He also supplied a mould to bend it around. It seemed to me there was no way the short, fat oak was going around that mold. Not without help anyway. So the first challenge was to figure out how to setup the mould so that I could get the leverage I needed. After thinking on this for awhile, I wound up tying the mould to 2 (real) trees, that were fairly close together. See the pictures below.

Next, I needed a steam box. A pvc pipe was not going to be wide enough. Luckily, I had some old gutter laying around. I put a test piece (2 dollar 2x4) inside 2 gutter sections and duct taped it up. A hot plate, a tea kettle, and a short metal tube were all I needed. After 2 hours of steam, I bent it around the mould and presto, it broke into 2 pieces. This was going to be more fun then I thought...

The test piece broke because it had a big old knot in the middle of it and was not hot enough, nor wet enough, after I steamed it.

The solution was to soak the oak for a couple of days in some fresh water, and then wrap the gutter in an old sleeping bag so it didn't lose so much heat (I forgot to mention that it was freezing out, -something like 10 degrees, more fun...). The actual oak piece had no knots and was not as dry as the test piece.

The oak bent beautifully. I leaned on the wood as hard as I could and started slapping clamps on. Results below speak for themselves.