Steam or boiling water can be used to plasticize wood so that it can be bent. The
wood can be formed over a mold or form. After drying, the bent piece should retain
its shape. What is hard to predict is the amount of springback you will get when the
wood dries. The advantage of bending the wood is that the grain will follow the
curve and not give you the short grain problem you get with bandsawn curves. You can
also create curves by laminating several thin pieces of wood and gluing them together.
This method is a better way of creating a specific curve from point A to B.
One of the short-comings of lamination is the time it take to create all the thin strips
and all the wood that ends up as sawdust. Half your wood can end up as waste.
When steam bending you want the grain to run parallel to the length, you do not want grain
to have run-out along its length. Knots and checks are also not good in the wood you
are trying to bend. Breakage may also be a problem; this will depend on the radius
of the curve. If you want to bend 10 pieces you may want to have 12 to 13 pieces
ready.
Wood should be bathed in steam for about 1 hour per inch of thickness. Wood is then
taken immediately from the steam box to the mold. You only have a very short period
of time because the wood will start to cool down as soon as you take it out of the steam
box. The wood is forced around the mold and clamped in position until dry.
The steam box should be long enough to hold the length needed and the length needed should
be longer than the curve. Allow extra. Do not seal the box, as no pressure is
required. Free flowing steam is what you want. You need holes to let water and
steam escape and a rack to keep the wood suspended in the steam. You need a heater
to produce a lot of steam and a container to hold enough water to produce continuous steam
for the amount of time required. A 5 gal. gas can will do but make it a new can and
not one that has had gas in it in the past. You can use a car water hose to move the
steam from the can to the steam box. Do not use garden hose, as it will collapse
from the heat. When selecting wood the best would be green riven wood. The next
would be air-dried and the last kiln dried.
When making the bend the outer convex fibers want to stretch and the inner concave fibers
will compress therefore a support strap will help in making bend.
Some of the best woods to bend are blackberry, white oak, red oak, magnolia, walnut,
pecan, hickory, beech, elm, and birch. Softwoods do not bend well. Other
hardwoods can be bent, but the success rate my be low.
Try it, you may find it to be fun and it may open up other wood working projects you can
try.