Bridgeport 412 slide motor problem

[gripper]

Hi, we have a Bridgeport 412 mill at work, it's a 1989 vintage and we have a lot of problems with the brushs in the lead screw motor always wearing out, which gives us a gross positioning error. If some one knows differently about what esle could cause this problem, please let us know. We were wondering if anybody has changed one of these motor's for the brushless type and what did you had to do to; a/ make it work and b/ what parts did you have to change? i.e boards, cables.
Thanks for your time.

[machintek]

I believe the 412 used SEM motors. When brushes are put in, the commutator needs to be turned down and the insulator undercut. Lastly the BOSCH drives need to be tuned. If all of the mentioned is not done, then yes, you may have accelerated wear on the brushes. According to the BPT service bulletin, it is expected that this need to be done every 4000 hours of running. This is equivilant to 2 years of running at 40 hours per week. I admit that I have seen some of these motors last 3 times that hour figure. There was a place that BPT used exclusively to repair these called CLARKSON.
I do not know of anyone that has replaced these motor/drive boards with something else unless it included the control.

George

[gripper]

Thanks again George.