Yes it is. Each glue has a manufacturer recommended clamping pressure.
Usually is is around 175-250 psi for hardwoods. Read more here:
firstname.lastname@example.org (Bruce) wrote:
I realized I didn't answer your question of "how much" I doubt many have
actually calculated their clamping pressures as that would be a real pain
in the ass to do. You'd have to calculate surface area of the clamped
area, divide by the number of clamps, torque each clamp to a known value
and perform the math to figure out how much linear force is applied by the
screw when twisted with a particular torque.
Clamping 2 boards, 1' square how many twist grip bar clamps?
144 square inches so to get 200 psi you need:
200 * 144 = 28,800lbs of total clamp pressure
28,800 / 1000 lbs** per clamp is 29 clamps!! What the hell? Is something
wrong with my math? I'd put about 4-6 clamps on that myself. I think you
better break out the C-Clamps.
**From the Bessey website, 1000 nominal clamping on their heavy bar clamps.
The way I see that, you can figure 1 clamp per 5 square inches.
I normally just tighten enough to not squeeze out all the glue, but enough
to squeeze out a bit. Don't tighten till the handle stops, but till it gives
good resistance. That's how I do it with Elmer's Yeller glue.
"Bruce" < email@example.com> wrote in message
By that link to attach a 32" oak face frame to 3/4" ply partition the minimum
force needed is 4800 pounds. Roughly the weight of my truck. On one stile of a
Somehow I think many here have gotten away with less.
clamp the boards together with enough pressure for moderate glue
"squeeze-out"...no more. It's not advantagious to apply excessive
pressure during a glue up. The mathematician and his calcs. are OT in
If you do that, you practically guarantee a glue-starved joint.
You won't get a feel for it until you do a few glueups, but you want
to apply just enough pressure to get a uniform bead of squeezeout. If
you get the pressure right, once the glue has dried, the clamps will
be slightly loose.
If you have to crank down on the clamps to close the joint, you
need to re-do the joint.
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