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Does stalling a motor cause any damage?

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  • lazlo
    replied
    Originally posted by Black_Moons
    a chinese 2HP motor will output 2HP without stalling.
    Lord, we've had this discussion so many times. Most Chinese motors, especially the ones shipped on consumer-class equipment, are wildly over-rated.

    Leave a comment:


  • Black_Moons
    replied
    a chinese 2HP motor will output 2HP without stalling. It just might not do it for very long before smoking! a well made continious duty motor would not smoke at its faceplate rating and likey is good for some more power before stalling.

    Stalling is generaly just a result of taking too deep a cut. its not an issue with your motor.

    And yes, Very hard on the inserts. Any time I 'stop' mid cut, it seems I snap the tip off an insert, Now I always make sure my tool is clear of the work before stoping.

    Leave a comment:


  • loose nut
    replied
    Originally posted by loose nut
    What kind of motor.

    Is it an old manly 'merican motor or is it it one of the new Chinese ones rated in pony power. Makes a difference.

    Just because it says it 2 HP doesn't mean it is if it's Chinese. It could be why he is stalling out. To heavy a cut for the motor.

    Leave a comment:


  • J Tiers
    replied
    Originally posted by loose nut
    What kind of motor.

    Is it an old manly 'merican motor or is it it one of the new Chinese ones rated in pony power. Makes a difference.
    Doesn't make any difference. Power needed is the same either way, just one way you do not GET the power.....

    Leave a comment:


  • loose nut
    replied
    What kind of motor.

    Is it an old manly 'merican motor or is it it one of the new Chinese ones rated in pony power. Makes a difference.

    Leave a comment:


  • philbur
    replied
    The 3 degree angle was the default value but as you say it seems that according to the diagram it should be 87 degrees. The horsepower, as stated, is net so yes 2 hp at the motor would be somewhat less at the workpiece. I was a bit sloppy, probably wasn't being paid enough.

    Phil


    Originally posted by Black_Moons
    Nifty, however i'll note you used 3 degree lead angle, From the diagram I would suspect that involves one that is almost parallel to the work (I think you wanted 87 degrees?)
    Also, theres transmission losses, and power used to drive the feed. So you can assume a 2HP motor is only gonna be good for 1.5HP or so at the spindle.

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  • Black_Moons
    replied
    Originally posted by philbur
    Heres a calc for a 2 hp cut.

    The calculator is here, interestingly it also gives an estimate of the tangential force:


    Phil
    Nifty, however i'll note you used 3 degree lead angle, From the diagram I would suspect that involves one that is almost parallel to the work (I think you wanted 87 degrees?)
    Also, theres transmission losses, and power used to drive the feed. So you can assume a 2HP motor is only gonna be good for 1.5HP or so at the spindle.

    Leave a comment:


  • philbur
    replied
    Heres a calc for a 2 hp cut.



    The calculator is here, interestingly it also gives an estimate of the tangential force:

    http://mpwr.iscar.com/machiningpwr/M...m&InsertType=1

    Phil

    Leave a comment:


  • Guest's Avatar
    Guest replied
    Yep, stallinig a motor is bad ju ju. After a few seconds smoke escapes as mentioned. Try not to stall the machine. I don't need a new 3 hp, 3 ph motor for my Webb mill but when I was refurbishing the mill a couple of years ago, I checked the price - $900. LOL. We've got to be careful.


    .

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  • bborr01
    replied
    I have stalled my B'port a couple of times. Power feeding a 2 or 3 inch face mill in annealed 4140 a little too fast. It is also REALLY HARD on inserts.

    Now that I know the limits, I try not to exceed them. If I see or hear the spindle slow down at all, I slow the feed down. I sense that stalling the motor is not good.

    Brian

    Leave a comment:


  • vpt
    replied
    Originally posted by KiddZimaHater
    R.C.'s right. It doesn't take much.
    Usually it happens when I'm manually cranking it, and 'hogging' off metal by hand.... not using the auto feed. (Thanks to my biceps of steel.. )
    1018 or 4140 steel, .030 depth, but cranking the pi$$ outta it, trying to remove alot of metal as quickly as possible.

    Never knew it was that easy. I don't hand feed much but I have taken off .020" chromoly before in my little atlas with a 1/2hp single phase motor without a problem. From what i remember in school working on the 3 phase machines I don't remember anyone ever stalling a machine. I did see lots of broken tooling though. lol

    Leave a comment:


  • darryl
    replied
    As has been said, stalling a motor makes is draw a lot of current, and the heat produced will have to be dissipated somewhere- in the windings and the start cap for the most part. Heat = expansion, cooling = contraction- a lot of that and there will be wear on the insulation. Heat in the start cap will dry it out eventually, and in a bad case can make it explode. Best to avoid this stalling in the first place.

    Having said that, I am reminded again of a device I built to protect another tool- in this case a die grinder. Basically it was a centrifugal clutch, but in reverse. You could hold the output shaft with your fingers and turn the motor on, no problem. The output would not turn, but if you let it begin to turn, the weights would force outwards, engaging the motor shaft. With the output shaft up to speed, the full motor torque could be had on the output- but if you stalled the output, the clutch would instantly disengage and the motor would not be stalled.

    I realize that in many if not most cases, there won't be room to add such a device to a machine. The idea is good, though.

    Leave a comment:


  • MaxHeadRoom
    replied
    A motor with no controller has only the protection of the overloads or fuses, with a VFD the current limit should kick in and normally would turn off and go into fault?
    Max.

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  • KiddZimaHater
    replied
    Your stalling a 2hp 3 phase motor? What depth and feed of cut does that?
    R.C.'s right. It doesn't take much.
    Usually it happens when I'm manually cranking it, and 'hogging' off metal by hand.... not using the auto feed. (Thanks to my biceps of steel.. )
    1018 or 4140 steel, .030 depth, but cranking the pi$$ outta it, trying to remove alot of metal as quickly as possible.

    Leave a comment:


  • .RC.
    replied
    Originally posted by vpt
    Your stalling a 2hp 3 phase motor? What depth and feed of cut does that?
    Would not take much to stall such a small motor...

    Leave a comment:

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