My heaviest steam bend yet… an oak board about 7” wide and 1.25” thick
and tapered to 7/8” at the other. It took several days of setup before I
hit on attaching the form to a 1000lb boat anchor of a vintage case clamp.
I tried doing it on the work bench with the form on its back but that
was hopeless due to the awkwardness and weight of the bending
apparatus that has to be loaded with a steamed part and quickly clamped
to the form.
I’ll need to improve this and maybe use a come-along or block-and-tackle
to pull it around next time but this at least shows I can get the shape
I want. A 6 foot pipe used as a lever only worked for about 1/3d of
the bend before I picked up the clamps and desperately screwed them
tight, alternating, to close the bend before the wood cooled too much.
I used a polycarbonate backing strip in between the steel bending straps
and the wood to prevent possible grain lift-out and I think a happy
consequence was it helped insulate the wood a bit, enough perhaps
to lengthen the working time in order to close the bend with the clamps.
There was a good deal of springback but the shape is still adequately
curved for what I want to do with it. The sharper the bend the
less the wood springs back because a sharp bend permanently
crushes more cells on the inside of the bend.