Reply by DannyB

@Nicholas
I’m a CS major/Physics minor, so I do understand they are going to spread load further, however, i will point out
1. The cauls in that picture are not cambered properly, so they are not actually spreading load very evenly, as the picture itself shows.

2. you are assuming you can’t apply more force to the ends of a caul than you can to a small area of wood.
Since it spreads out load better, you can in fact, use a lot more force without damaging anything, precisely because it is spreading it out.

So it’s not a simple game of “i can apply 1050psi with a pipe clamp, and thus, with a caul over 48 inches, i can only get 1050/48”