So for decades of hobby woodworking I’ve gone along my merry way gluing up panels from time to time with little thought to calculated glue pressure. Based on just watching how others seem to do it. See photo below of one of my recent glue ups. I’d put a parallel clamp every 6″ or so with decent squeeze out and call it good. Then I started reading articles on calculating glue pressure needs and amount of psi various clamps can produce. Now I feel like an idiot. Take 3 board 3/4″ thick cherry panel glue up, 40″ long in photo below. That’s two glue lines 40″ x 3/4″ x 2 = 60 sq. in. of glue area. Titebond apparently recommends 175 psi to 250 psi for its glues. Ok, 60 sq. in. x say 210 psi = 12,600 total psi needed. From another FW article a parallel clamp can produce average of 370 psi. So how many parallel jaw clamps do I need 12,600 psi / 370 psi = 34 clamps. No this can’t be right! Is it? If it is what good are parallel jaw clamps? Pipe clamps produce average 1,050 psi so with those you need 12 clamps. Unfortunately, it looks like my happy go lucky “perfect panel glue ups” have been so wrong. Have I got this right?
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