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Here's a good thread and similar photo

http://www.luthiersforum.com/forum/view ... 01&t=18390

40 Cam Clamps (x $15=$600 - should have used a go bar system)

Go-bar deck with a plywood caul that has a foam edge:

This is probably going off on a tangent, but when the bars bend that much, aren't you actually getting less clamping pressure than if they were a bit shorter?

I believe it's more. Where do you think the pressure's going? The more you bend the rod, the greater the resistance. The two ends of the rod are the only release points.

More bend in the bar stores more spring energy, but does not apply any additional load. Once the bar reaches it's critical buckling load, the clamping pressure it applies is constant. For a 3/16" x 24" fiberglass bar, this point is reached with about 1" or less deflection and under 3/4" reduction in length. If you want to understand this, Google 'Euler theory column buckling ', or refer to any decent mechanics of materials text (Hibbeler, etc.).

Another consideration: for a constant diameter bar, the shorter one applies more pressure, so a 3/16" x 28" bar will exert a wimpy 5 lb clamping pressure or so, while the 24" bar will apply 7-8 lbs.

And finally - just because it will come up again - the clamping pressure is always, always, always applied along a straight line between the two ends, so a bar with ends aligned such that they are vertical will never apply any side forces to a brace or box, while a bar whose ends are not vertical will apply some degree of side force (a very handy thing, indeed).