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There’s a great post over on This Old House by Norm Abrams covering the proper care of common power tools, including a great description of how to clean motor brushes.  An excerpt:

“Most small power tools have two “brushes,” solid blocks of carbon graphite that conduct electricity to the motor’s spinning armature.  Friction gradually wears these brushes away, and if they’re not replaced, the motor loses power and eventually quits.  You can tell it’s time for new brushes when you see lots of arcing — small, harmelss sparks inside the motor housing as the tool is running.”

Easily accessible brushes are a prime feature on high-end power tools as the manufacturer expects the tool to see a long and productive life.  If you’re not already familiar with this kind of maintenance, be sure and give this a read.  It’s complete with drawings explaining the whole process.

TLC for Power Tools [This Old House]


8 Responses to Norm Abrams on “TLC for Power Tools”

  1. nrChris says:

    Very useful post. I have noticed sparking inside of my older Craftsman circular saw. I am going to use this as an excuse to buy a new one. There are no brush ports on this saw, but I am thinking of ripping it apart to try to replace them anyway. Anyone have thoughts on this? I figure that as long as I am careful and layout the pieces as they come off that I should be able to at least access the brushes–I believe that I have a source for new replacements too so that isn’t a consideration. It will be nice to have a second circ, but if it dies in the process it will be no biggie. Advice appreciated.

  2. Rick says:

    I guess that explains the sparking from my dad’s ancient craftsman drill..
    I’ll have to let him know..

  3. T says:

    High end power tools? The $15 angle grinder I bought two weeks ago from Harbor Freight not only has accessible brushes, it came with a replacement set. This is about as far from high end as it gets.

  4. James says:

    This video demonstrates router brush replacement. Unfortunately, registration is required:


    The process for two units are shown: one with externally accessible brushes, and one that requires removal of the housing.

  5. I’ve noticed some sparking in my Porter-Cable router and thought I might need to change the brushes, but haven’t had the time to get into it; this might make it easier.

    I also noticed sparks in my brand-spakin’ new Bosh PS10-2 I-driver, so I wonder exactly how much sparking signifies a problem…

  6. Jeff T says:

    Just because an electric tool sparks doesn’t mean it’s time to replace the brushes… I don’t know why they said that.
    Almost anything you have if you look at the motor when you start it especially will arc even out the side on some models – its just nature of the beast. When the motor is running it should just spark quite a bit less.

    If it sparks much more than normal I’d say it’s time to check them first…

    Yeah, I have that same angle grinder and was surprised it had those brush access points. Funny thing is since it’s Harbor Freight, have fun getting more brushes ala carte from them! I guess you could fabricate some? That’s the only downfall of HF tools… but it sure isn’t bad for the money so far.

  7. eschoendorff says:

    I have noticed that my cordless drills have an electric brake system that sparks a little when I let up on the trigger. No worries…

  8. Joe Pardo says:

    Do you always need to drill a hole before installing screws?

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