The panels I have been cutting are measuring square on opposite corners, (with framing square), but out by about 1/8 inch in 4 ft when using the square on the other corners. If I throw a tape corner to corner, my measurements are the same.
OK, math time. Using Pythagorean Theorem (c2=a2+b2), I did some figuring on paper. Taking a model of a 2ft by 3ft square panel, and converting it to 8th's of an inch, I have a piece that is 192/8ths by 288/8ths. Figuring for the hypotenause, I get 346.13/8ths.
Now, taking the same piece and recalculating it, this time taking 1/8 inch off the short side (191/8ths instead of 192) and calculating, I get 345.57/8ths.
Flipping the numbers and this time taking 1/8 inch off the long side (287/8ths instead of 288), I get a hypotenause of 345.3.
Converting 8ths back to inches, it is 43.19" vs 43.16". There is no way I would discover this on my tape measure going corner to corner.
Isn't it true that Pythagoras is only working with a known square angle to start with? How does this affect tolerances in measuring corner to corner to square? Why am I so obsessed with this right now, I'm not getting any work in the shop done? Why is the LOML throwing all my stuff into the yard?
Maybe I'm overthinking this, but till I get it straight in my head, I can't begin to work on why my panels all come out 1/8 out of square with 2 corners square.
Someone, please save me from myself!!!!!!!!