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Hammer drill that only sparks in hammer mode?

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  • Hammer drill that only sparks in hammer mode?

    I have a reconditioned Milwaukee hammer drill model 5380-81. I was drilling a floor in a dark closet and noticed there are fairly steady sparks inside the vent holes when it is in hammer mode.

    I've searched everything on this forum about sparking drills, I guess I'm hoping you guys will tell me this is nothing to worry about, but
    I don't see sparks when it is running without a load in regular mode. I have drilled about thirty holes in 4-inch concrete with it, so I think the internals should be pretty worn-in by now.

    There's a month left on the warranty, but it would cost quite a bit to send it back. I also expect it will be hard to get them to RMA it for sparks unless I really push, and I hate doing that too.

    I paid a hundred dollars for it. The post office says it will cost $35 in postage to send it back.

    I'm curious what you guys would do in a similar situation?

  • #2
    Re: Hammer drill that only sparks in hammer mode?

    Have you considered calling Milwaukee customer service and asking a service technician?
    Or, calling the Milwaukee service center and speaking with someone familiar/experienced with your tool?

    A phone call can accomplish a lot [most of the time]



    Cactus Man

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    • #3
      Re: Hammer drill that only sparks in hammer mode?

      I think it will be fine as it probably does that under load because of the pulsing of moving parts in hammer mode. You know, the kickback against the armature causing vibration against the brushes. In theory it makes sense anyway.

      I have a Hitachi DV18DL and maybe I can get it out and try the same thing. If so I will report my findings here. Later!

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      • #4
        Re: Hammer drill that only sparks in hammer mode?

        Cactus, thanks for the advice, I'm asking here first to avoid the customer-service briarpatch if I can. If I have go that route, it will be through the Amazon reseller through which I got the drill, which is a reconditioned tool store in Georgia with three-letter name that sounds like a Navy non-com.

        Shadow, that's what I told myself too, but it might be wishful thinking. Anyway, I took the drill in a dark bedroom and ran it some more, and I found if I look into the top vent I can see a small, steady blue spark on the right side of the motor, regardless of the mode. Are brushes supposed to do that? I thought arcing was generally destructive, but I don't know enough about motors.

        So the revised question is, if you run a drill in a dark room, is it normal to see very small steady blue spark? Should it be only on one side, if brushes are in pairs?

        The drill may be OK and will run for years, but on the other hand it could burn out and I need it to work. Damn. If I had paid another fifty dollars for a new one, I would have had a five-year warranty. I thought I would only need this tool for a few weeks, boy was I wrong.

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        • #5
          Re: Hammer drill that only sparks in hammer mode?

          Yes blue sparking can be present unless you have a perfectly round commutator and both brushes are in perfect condition. Excessive arcing isn't the greatest thing in a motor, but it is electricity and as those parts wear it usually becomes more common. Arcing on one side is normal as you have a 2 pole motor, one being positive and feeding the armature and the other pole being the negative/ground. Later!

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          • #6
            Re: Hammer drill that only sparks in hammer mode?

            Thanks, shadow. I appreciate your responses to my issue. I guess I will ask someone to show me how to inspect the brushes, and that should clear up the doubts.

            I talked to Milwaukee cust. service as cactus guy suggested They said my refurb warranty doesn't cover the brushes anyway, as that is considered part of routine maintenance and the responsibility of the owner. They told me I should take it to an authorized dealer for servicing at my own expense.

            My neighbor's son-in-law sent me a link to this discussion on another forum, which makes me think maybe sparking is common and only worries us newbies.

            http://forums.anandtech.com/showthread.php?p=17080591

            P.S.: here's the price of brushes

            Milwaukee Replacement Part # 22-16-0025 CARBON BRUSH (2 PER PACK)
            $29.31 + $9.99 shipping

            Holy cow
            Last edited by mrs_catgut; 04-13-2010, 02:06 AM.

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            • #7
              Re: Hammer drill that only sparks in hammer mode?

              Well at least the brushes can be replaced. I will tell you that putting new brushes on a severely out-of-round commutator (sectional copper parts of the armature) will eat new brushes up in no time. That isn't to say your drill's armature is trash, just saying this is an issue that can happen, but not likely with something fairly new and hardly used.

              Don't know how your drill motor is setup, but it could also be weak springs (from heat usually) letting the brushes bounce on the commutator while spinning. BUT.......

              I seriously doubt it's anything more than normal arcing. When I was involved in the R/C hobby I would smooth out my armature commutators on a lathe with a diamond tip cutter which would make them like new again, just a bit smaller in diameter. Then install new brushes and things would be fine, but as those things wear the arcing would start again. Just the electrical nature of the beast. Just use it like normal and see how it goes.

              BTW, I don't think you've mentioned any other issues like a burning smell, smoke, etc... if none of these things are happening I say keep on using that thing. Later!

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