Reply by higtron

“Wow, I guess I’m old-school. I just use a framing square and hold it up to the light.”
Now I agee with pintodeluxe if you have a framing square that you trust, or what ever square or device everyone should know that nothing is perfect it just what tolerances is good enough .01” / .001” / .001”, or is everyone trying to get to the nearest molecule. It seems to me you get the squareness of your fence as close to square as you possibly can useing what you have without breaking the bank if you have a $20 square that is close enough to your particular tolerances cut a piece of wood and check that sucker with your $20/$500 square, and call it a day.

-- If I cut it too short I can scab a piece on, but if it's too long what do I do?