View Full Version : Issues with Harbor Freight Mill

08-27-2003, 07:27 PM
Has anyone else experienced problems with the built in Circuit breaker tripping all the time, even without a load on the motor ?
Mine does it sometimes on low, but on high speed, it happens throughout the entire speed range. I've even gone to the point of pulling the end bell on the motor, reoiling the bearing, cleaning the commutator, and cleaning up the brushes, the Comm. was alittle dirty, but not bad for a DC motor, ( I've had many of them apart before).
Has anyone else got ideas on this, or heard about this issue ??
My next step is to pull off the drive assm. and check for gears binding inside..... which is the only other thing that comes to mind.



08-28-2003, 12:24 AM
Check if the earth wires are right. Look for suspicous connections. Check if the field coils are OK, check for continuity on the field coils.
Check for power spikes on the supply to the machine.....


08-28-2003, 12:50 AM
Is this a spindle motor, or a servo motor (on a cnc axis) you are talking about? If the latter, check that your settings for acceleration and deceleration "ramping to speed" are not too aggressive.

08-28-2003, 01:22 PM
Klox, yes that is my next move, I was going to check into it last night... but took one look at it @ 10:00pm last night, and just went on to doing other things out of frustration.
It never fails, I bought it about this time last year, and spent the last year building my shop, and finally it's up, mounted, wired in.... and when we finally get to use it, it's got issues..... doesn't things like this drive you up the wall ??

I'm planning on a look / see tonight, I've got things to make, and metal to burn!! well, not acutally burn ... but ....you know.


09-01-2003, 10:52 PM
would it be possible the gears arent meshing well? I would suggest you loosen up the bolts on the motor mount(the black plate that covers the top of the head) and re-align it so its not making much noise..

While you do this, you want to have the motor on, but not super high, Itll make noise when its in some positions and very little in others.


09-02-2003, 12:11 AM

I am not familiar with Harbor Freights version of this mill but I am familiar with another brand and have seen problems similar except this mill burns up a lot of fuses. What I've done is open the control box and look for some trim pots on the controller board. These are current limiting pots on the machine I'm used to and by making SMALL adjustments to these you can get the motor to run without excessive amperage draw. One of the other symptoms is the motor runs hotter when the trim pots are off. If you have noticed this when in low this may be the fix. Hope this helps.


09-02-2003, 01:08 AM
Problem found!!!...... in the headstock of the mill, where the spindle passes through, there's an upper and lower bearing on the spindle shaft. Apparently upon assembly in the factory, they must have overpressed these into the housing, because upon trying to remove the bearings and shaft from the housing, just for Shi'#'s and grins.... we checked the spindle rotation after moving the shaft only 1/2 a millimeter or so........and whala! it entirely freed up. I've used the mill since, and it doesn't shut down anymore, Although, I can say that I'm really not happy with the construction, and some of the parts they chose to use in the gearbox.....I question, but I'll see how they hold up for now.

Thanks for all the input.... and suggestions guys!