My mill motor stops. What is wrong?

[jaru-eri]

I have a Taig mill and the motor stops sometimes. If I turn of the switch for a short time, it starts again. Last time it gave some stuttering noise before it stops and it was not heavy loaded.

What can be wrong?

[cartertool]

Sounds like the thermal switch kicked in. Were you taking heavy cuts? Did the motor get hot? Is it fully plugged in?

Originally Posted by jaru-eri I have a Taig mill and the motor stops sometimes. If I turn of the switch for a short time, it starts again. Last time it gave some stuttering noise before it stops and it was not heavy loaded. What can be wrong?

[jaru-eri]

Thankyou.

I didn´t know there was a thermal switch. The motor was a bit hot after I did some side cuts in aluminum with a 10mm end mill.

[awerby]

Don't you use 220v 50hz power there? Are you using a step-down transformer to knock it down to the 110v that the motor wants? While the Franklin motors that Taig provides with their CNC mills work quite well on US 110v 60hz current, I'm not sure that even if you stepped it down to 110v that it would be happy with 50hz (and if you're running it on 220v, you should definitely expect major problems). There might be a way around the frequency problem (perhaps an electrical engineer will read this and suggest something) but the simplest solution would probably be for you to find a 220v 50hz continuous-duty motor 1/4 hp or better, and use it instead of the Franklin with the power you've got.

Andrew Werby
www.computersculpture.com

[jaru-eri]

I´m using a step down trafo, so the problem may be our frequency at 50 hz. The motor is marked with 60 hz.

I´m not an expert with motors but my first thought would be that this only would make it run a bit slower.

[noisillator]

Originally Posted by jaru-eri I´m using a step down trafo, so the problem may be our frequency at 50 hz. The motor is marked with 60 hz. I´m not an expert with motors but my first thought would be that this only would make it run a bit slower.

No, it's just like a transformer. The motor windings are designed to exhibit a certain minimum inductance in order to provide a certain minimum inductive reactance (resistance) at the frequency of operation. Reducing the frequency reduces the reactance, and that increases the power absorbed by the windings.

[jaru-eri]

Do you think this is a serious problem or can it be solved by mounting an extra cooling fan to the motor?

[noisillator]

Originally Posted by jaru-eri Do you think this is a serious problem or can it be solved by mounting an extra cooling fan to the motor?

Even if an extra fan keeps it running, that might only mean that the thermal switch is cooler. There might still be portions of the windings or other components running at temperatures above their ratings. Even ignoring the likelihood of a shortened lifespan and reduced reliability, there are safety issues in this. Personally, I'd get the correct motor and be done with it.