>There is a bit of slop in the >bearings, but I don't break too many bits.
I broke a .031" carbide bit yesterday trying to drill at a Z axis feedrate of 100 IPM and 30K RPM. Broke another this morning at 50 IPM, finally settled on 25 IPM. Vibration, runout, feedrate, RPM, material and bit size are typical suitability determinants.