Question about Bosch Electric Table Saws

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Motor brushes spark like crazy!

The motor didn't come up to speed anymore. It would come up then drop down a little. Then after a while it started sparking. I replaved the brushes but it still sparks.

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  • rsbs_seidema Jan 15, 2009

    Thanks, I will most likely replace the armature. When I spin it around between my fingers I can feel a ridge in it . I think that's were the brushes are bouncing causing the sparks.

  • James Johnson
    James Johnson Sep 10, 2014

    The field in my mind would be the better fix. Replace the field and sand the commutators down a bit till shiny and change brushes. The new armature is over $100, but the the new field is about $50 with shipping. Set of brushes are cheap too and change the bearings on each end of the armature too as those tend to seize after awhile...

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  • Master
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If you already replaced the brushes you could have a couple problems, the least is the armature commutator needs cleaned and the more expensive is that it needs replaced. This is a problem unless you want to tackle taking the motor partially apart. Let me know what route you want to take either a repair center or looking at the commutator.

Posted on Jan 14, 2009

  • David Ford
    David Ford Jan 15, 2009

    Before you buy a new armature take it to a repair center and ask them to test it on a growler helper and if OK see if they can turn and undercut it for you and after turning I would recheck it. Also if you do replace it buy new bearings, it will save a headache in the future.

  • James Johnson
    James Johnson Sep 10, 2014

    It could also be the FIELD that is the culprit, but also replace brushes while at it, and also you could try sanding the commutators down a bit upon replacement.

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  • Bosch Master
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The electric field if depends on model the sliding contacts could be worn look good if it sparks on one side more the the other side replace the electric field allways first if both sparked the same it could be also thermal short in the armature

Posted on Oct 18, 2016

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