A job at the old paper mill in Kalamazoo taught me to always double-check my bevel angles with a gauge, not just the grinder setting. | Boilermakers - The Community Guide
Yeah, that's a hard lesson to learn. I messed up a whole batch of parts once because I trusted the angle guide on my bench grinder was dead on. Turns out it was off by almost two degrees after some wear. Now I keep a cheap magnetic angle finder right on the workbench and check the actual piece after every few passes. It adds maybe ten seconds to the job and saves so much headache. What kind of gauge do you use to check yours?