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Bench belt/disc sander going slow - what's the problem?

Discussion in 'Tools and Materials' started by ^woody^, 21 Aug 2018.

  1. ^woody^

    ^woody^

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    I have a bargain chinese no name belt/disc sander thats been incredibly useful over the years, but now the motor spins up normally and sounds fine, but slows to a stop when just light pressure is applied to either belt or disc.

    Is there a simple fix for this, or is it sander heaven for it? :(
     
  2. Notch7

    Notch7

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    induction motor or universal?

    Its obvious, universal is noisy!

    If by chance its induction, then it could be capacitor

    if universal it could be brushes or speed controller if there is one.
     
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  3. ^woody^

    ^woody^

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    It's actually quite quiet with a satisfying industrial hum rather than a harsh motor sound. I suppose there would be a plate or something on it somewhere telling me about the motor? I'll have a look, but if it is a simple capacitor then that would be DIYable - especially as I've just had a look at the price of some of these things.
     
  4. Notch7

    Notch7

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    That is an induction motor so could be a capacitor failure -its hard to get exact replacement but close to the rating would be good enough.

    It could fault in motor windings....

    hopefully an electrical expert will be along soon to give proper advice (y)
     
  5. foxhole

    foxhole

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    My old table grinder needs assistants to get turning but runs fine once up to speed , they are very cheap to replace .
     
  6. mattylad

    mattylad

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    sounds like you need a new motor start capacitor.
    ebay has them by the bucket load, just choose one the same values as yours.
     
  7. I'd guess it's either the centrifugal switch failing to change over from the start cap or the run cap has failed. I'd get a multimeter on the run cap and see what happens as you start it up in terms of current.
     
  8. conny

    conny

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    We have a battery operated 4" grinder with a similar problem. I pull the brushes out and give it a good blow out with an airline, check the brushes are sliding freely in their boxes and away it goes for a few months.
     
  9. A bench grinder will have an induction motor
     
  10. conny

    conny

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    A small one may have a universal motor which has an armature and carbon brushes. Look for two caps on opposite sides of the body. There is usually a small screw to indicate them.
     
  11. DIYnot Local

    DIYnot Local

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