Servo Motor Brush Life

[Bob La Londe]

Anybody use their Electrocraft driven Hurco enough to have a workable estimate on servo motor brush life and/or a safe replacement interval in hours, revolutions, or screw travel?

I have the manual for the Hurco, and it does cover some maintenance items like refilling the oil reservoir and greasing the spindle spline, but I do not see anything on brush life. The fact is brushes wear out, and I would like to replace them periodically before they cause part problems, crashes, or rotor damage.

I really plan to use my machine when I finish retrofitting it. I expect it will be running a lot. I have easily put over ten thousand hours on my Taig since I bought it, and I expect to use this mill about equally or more since I plan to retire the Taig eventually. Atleast long enough to redesign it better for high speed spindle work and better life of precision.

[Al_The_Man]

There are so many variables over time that it is almost impossible to give a life span of brushes, the key thing with DC brushed is regular maintenance and inspection, time depending on the duty cycle of the machine, any machine that is in continuous daily use would be brush inspection at least once/year minimum.
It is usually one of the quickest and easiest maintenance item to check, cheap insurance.
Al.

[Bob La Londe]

There are so many variables over time that it is almost impossible to give a life span of brushes, the key thing with DC brushed is regular maintenance and inspection, time depending on the duty cycle of the machine, any machine that is in continuous daily use would be brush inspection at least once/year minimum.
It is usually one of the quickest and easiest maintenance item to check, cheap insurance.
Al.

Once a year would be awesome.

I know on brush spindles I measure brush life in hundreds of hours not months or years, but they get lots of load. Of course servos aren't turning at 20000-34000 rpm either.

I guess I could do some math and work backwards from that to get number of revolutions, and then convert that to inches traveled for a best case worst case brush life estimate. Then I can compare brush length and commutator styles. Mach does supposedly keep track of inches traveled.

Its not easy to check on a KMB1. Atleast not on mine. All the servos are hard to get to. The Y-axis one is down under the machine and hidden. The X is semi accessibble. The Z is accessible, but hidden under the front cover.

[underthetire]

As al said. We had old Hurcos with those motors. Changed ~10 years or so, but yearly maintenance, including light compressed air to get all the dust out. What kills them the quickest is coolant getting in them. Avoid getting them wet and your in great shape. A commutator stone is quite handy for those as well.