If anyone could please comment on my "bounce" question below from an earlier post in this thread I would be very grateful. Lenny


The commutator does not appear to have worn down much during it's lifetime. A growler test shows no shorted windings to ground, The areas between some of the the segments however appear to be a little ragged and opened a bit from the arcing, no doubt. A dial indicator on the commutator shows an out of round condition totaling 1.5 thousandth's, on each side for a total of three thousandth's for the entire piece. According to a machinist we consulted this doesn't seem like enough to warrant turning the commutator, but I've been considering something else. With this motor spinning at 9000 RPM would a 1.5 thousandth's out of round condition be enough to "bounce" the brushes and make them arc? Brushes are now trued to the commutator, holders are new, and each brush is mounted stationary, and it's relationship to the position on the commutator cannot be altered. I can't figure out what else could be causing this? Lenny