[rames14]

Ah, the good old Apprenticeship days. Big Murf, I think you are meaning that you should have two threads exposed because if they were in the nut (and not sticking out), they wouldn't equally hold the torque load. This depends partly on how the threads are cut or formed (rolled, cut, etc). For higher quality bolts, the tolerance is such that this should not be a problem, but still a good rule of thumb. Definitely if you see a color change - starting at a very light straw color, the microstructure has changed and no longer has the same mechanical properties. However, mechanical properties can start changing as soon as 400 degrees. Not cutting on grade 8 bolts is a good idea.