SainSmart Genmitsu CNC Router Machine 3018-PROVer. I’ve been using 1/8 bits and they dig to deep. I’ve tried some of the others but there aren’t any that I have. I think the bits that I select have a longer shaft than the ones I have and maybe that’s why they are breaking. The software probably knows the size of the shaft length or something like that. The 3018-PROVer has the limit switches and after following the directions the programs runs and goes to the first cut and then stops because it can’t go any lower and it trips the limit switch. Any ideas ?