Woodbending Tests

Wednesday, February 5th, 2014 @ 5:19 pm

bend, oak, soak, steam, wood

I’ve got this idea for a stepstool, springing from an old idea I drew over the summer, and I’ve brought it back in the past week to figure it all out.  The steps and any joinery are mostly just ideas at the moment, as I’ve never bent wood before, and the bends and laminations of this project are the crux of its success, so I’ve been experimenting with those so far.

I started by milling a 7′ length of oak into 1/8″ strips, about 2.5″ wide, and steaming one in a steam box for about 20 minutes after it’d been at 150 degrees for quite some time.  Insufficient time in the box led to the strip breaking when we bent it around that tight radius at the corner of the triangle.  That’s my form to the right.  Those blocks laying beside it are curved cauls for clamping the strip into the concavities between each rounded corner of the triangle.  After the strip broke, and it was the end of the day, I soaked its two halves in a smaller box one of our woodshop managers uses for soaking and boiling in making shaker boxes.

After two days of soaking – over the weekend – and then boiling all of that water over a hot plate, I was able to bend the two strips around the tight radii of the form, without much incident once I’d gotten the bending procedure down.  Pulling hard on the metal strap as it comes around the radius helps a lot in supporting the wood fibers as they take that tight curve and want to split outward, like spines, away from the form and the rest of the wood.  After those tests went well, I tried bending some heavier pieces I’d been using to weigh down the thin strips in the water, and since they’d soaked and boiled for a while as well, they bent just fine.  1″ oak and a heavy 1=1/8″ or 1-1/4″ thick maple strip took bends pretty nicely with minimal breakage just using heavy clamps to get them down over some blocks of wood.

Next up: building a soaking/boiling tube big enough to house the long strips I have now so that I can try a full bend of a full length piece and see if how that holds up.