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armature question?

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  • armature question?

    My son has a nice industrial floor drum sander.(push alog type you normally hire) Unfortunately it is sparking when turned over. The brushes are not desperately worn but we will replace anyway.I noticed a slight chip on one of the armature teeth about the size of a half of a grain of boiled rice.I wonder if that is causing the problem as the brushes look a little chip damaged in this region .What is the best way of fixing this beofore laughing at me is it possible to make some very fine brass dust mixed with a very little epoxy just enough to bind .Then applied to the spot then filed and sanded to perfection or is there a better way????? Alistair
    Please excuse my typing as I have a form of parkinsons disease

  • #2
    Are you referring to a chip from the copper commutator ?.

    The armatures on universal motors usually spin at very high speeds .. 15000 to 30000 rpm not being uncommon. So a glue bond would have to be good n strong to survive.

    Sparking is often an indicator that the armature may have stalled and melted the commutator segment bonds and/or possibly shorted or open circuited the windings.

    Does you damaged commutator segment have similar marks/damage on the opposite side?. That would be a good clue to what may have happened.

    And don't forget to measure the impedance of each side of the field coil. They should be roughly the same. A short on one half coil can also cause an armature to fail.

    If the armature is could have its commutator replaced at a rewinders , but on smaller equipment its usually cheaper to fit a new armature.

    Last edited by MrSleepy; 08-11-2014, 03:29 PM.