Reply by bandit571

Go out and get a decent “Speed square”. Clamp it to the sole. Leave it just a hair off the sandpaper surace. Use it as a guide to check when square. Repeat for other side. Most irwin brand speed squares ( Orange plastic ones) are less than $5 each. Grab two, one for each end. Just a “C” clamp to hold them in place. Take along a GOOD square, and check each speed square, before you buy it. Sometimes, I will go through half a rack of them, just to find a “true” one. Forgot the square? Grab a framing square to check the speedos, simple.

-- A Planer? I'M the planer, this is what I use