: I applaud your use of geometry, which is a wonderful thing and sorely lacking
: in the current crop of engineers. However, the wood itself is capable of
: evening the stress over its own length, without resort to mathematics. If
: you attach the ends and put in a centered spreader to give the maximum
: beam you require, the wood will assume a natural equilibrium position.
: Scribing additional spreaders to fit within the existing spaces will lock
: in the shape.

: True, the ends should theoretically be free to rotate, but that can be taken
: care of by clamping during the bending process and connecting afterwards.
: What the geometric method doesn't account for is variations in the
: properties of the wood over the length - however, I assume the lengths of
: the scribed spreaders would match your theoretical values within a few
: percent.

: The real advantage of the scribing technique is that the bevel angles at the
: ends of the spreaders is available directly and you can mark it with a
: pencil. I'd wager that a theoretical formula to find the needed bevels on
: the spreaders will be much harder to come by mathematically! If you figure
: it out, I'll look forward to seeing the derivation.

: I like that stressed kayak-shaped strongback - too bad I saw it yesterday
: after I had already started my own conventional lumber strongback. It's
: made of three 14 foot 2x4 with 2x4 spacers to give a total width of
: 7.5", with birch ply top and bottom. It's glued and screwed, and oh
: my god, it weighs a ton! To paraphrase Darth Cheney, "you build the
: boat with the strongback you have...."

: Cheers, Carl

HEY, a possible strongback thread. I wonder how many variations their are. Here is a pic of mine. It is 20 years old, made from 8 x 2 truss lumber in a T section. Weighs a lot and is screwed permanently to the floor. I could build with two by four strips and it wouldn't budge. I would need to lengthen it though if I wanted to build a double.

Et