X2 motor temperature

[Pretorien]

I have a (Grizzly) X2 - about 7 years old - fitted with a LMS belt drive. It is not CNC but I do have 3 axis DRO. I have noticed that after about 45 min to 1 hour of use ~ 70% duty cycle running at full speed, the motor is quite hot - one can "touch" it but you would certainly not rest your hand on it. This is not a high load application 1/16" -1/8" end mills cutting perhaps 0.020" per pass in free machining brass. I don't know the feed rate but based on time/cut, I would guess no more than 1.5"/min.

Is this normal behavior or a warning of incipient failure?

Thanks

Pretorien

[dang]

I have the HF version of the same mill. The best thing to do for these things, as I've learned in a very quick manner, is to have backups for all the electronics. That means the board, and the motor.
Your's is still running, I'd recommend you squirrel away some green here and there to buy the replacements.

[Pretorien]

Thanks - sounds like a reasonable idea - and the second lesson is:
If it says "made in China" - move on. Electric motor technology is not exactly "cutting edge" - there is no reason for this kind of problem. (My bandsaw - Delta - and my drill press - Walker Turner - are both pre WW II and both are still running on their original motors!)

[LongRat]

I just replaced the brushes in the motor on my X2, as it was arcing badly and speed hunting. This did not seem to make any difference to the temperature though, it was never as hot as you describe running similar operations for over 2 hours at times. I estimate I had about 2500 hours on the motor before the brushes were changed.

[Pretorien]

Mine is not hunting. I would guess that I have about 500-800 hours on it (I may use it intensely for 2-5 days and then not touch it for 4 months) I have noticed that if I crank up the motor speed pot too quickly, it will cut out - then need to go back to zero and ramp up more gently. I assume that there is some sort of an overcurrent sensor and cut off in the electronics.

At this point, I'm going to let it limp along with repair as needed. I gave some thought to looking at motor alternatives but since it will eventually be demoted to a precision drill press + rough dimensioning machine after I get my {planned} CNC Taig, a mill "project" doesn't seem worth while.

[LongRat]

There is an overload circuit in the speed control electronics. It kicks in if you take a heavy cut too! If it doesn't kick in in time, the plastic drive gear will let go next.