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I have this Milwaukee corded drill: 1/2 in. Pistol Grip Dual Torque Hammer Drill.

Recently, I pushed the motor too hard while mixing thinset mortar. I got a burnt motor smell and bit of smoke. I have now learned that bigger mixing paddles are not always better! Have I caused serious harm to the motor? Is there anything I can do to ameliorate some of that harm? Or maybe drill motors are designed to survive such occasional abuse.

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    @Ecnerwal I hope that you mean "Nope, you didn't cause serious harm" but I fear you mean "Nope, there's nothing you can do."
    – Matthew Bourque
    Commented May 26, 2022 at 16:13
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    Motor windings are insulated with a thin layer of varnish. The smoke is usually some of that varnish being burned off, and then some of your motor windings are no longer insulated one from the next, so that part of the winding is shorted out, which usually leads to further heating and further damage. Repair was economically sensible some decades back. These days, not so much. The new parts frequently exceed the price of a new tool, and as for a motor rewinding shop, good luck finding one at all; finding one that will work on a small tool; and having that not cost more than a new tool.
    – Ecnerwal
    Commented May 26, 2022 at 16:23
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    Nothing you can do about it now, repairs really aren't possible. I'd address this practically: If it works, use it, if not replace it. But bc the insulation may have breaken down enough to cause a short, I'd be sure to only use it on a GFCI protected circuit.
    – George Anderson
    Commented May 26, 2022 at 17:27
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    @Ecnerwal You're probably right, but I'd open it up and see what the motor is and whether I can get a replacement (assuming it doesn't work now, or fails soon). Drill motors are fairly standard - I've specced one for something completely different so looked into them a few years back
    – Chris H
    Commented May 27, 2022 at 9:46
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    As for a case where someone restores windings (albeit on something bigger than a drill) there was recently a story on hackaday where a lady restored a generator, making the new windings by hand with a dedicated tool.
    – hlovdal
    Commented May 27, 2022 at 14:14

3 Answers 3

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This has happened to me before and in general the tool continues to work mostly fine. I suppose there might be a drop in power output but I’ve never really noticed it.

I realized that slightly more expensive brushless motor drills often come with an electronic control that will shut off the motor before it gets damaged from being overdriven. Those are useful for avoiding the problem altogether.

Bottom line in my experience is, keep using the tool until it stops working unless you have a good reason for an upgrade.

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    Think it would depend if it was a little wisp of smoke or a few seconds of smoke.
    – crip659
    Commented May 26, 2022 at 17:36
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    @crip659 I’ve definitely made a mess of smoke with both cordless and corded drills and in general they still work.
    – RibaldEddie
    Commented May 26, 2022 at 18:42
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    many motor winding wire coatings like varnish or lacquer produce A LOT of smoke when over-heated or burned. While a wisp from an LED or transistor signals death, you can probably fill a room with motor smoke and still have no measurable performance impact.
    – dandavis
    Commented May 26, 2022 at 20:19
  • @dandavis: On the other hand, if one continues to use a smoking drill it may eventually burst into flames quite dramatically, so think of the smoke as being a warning not to keep abusing the drill.
    – supercat
    Commented May 28, 2022 at 2:33
  • It's over two years later now and the drill is still working fine, which supports this answer.
    – Matthew Bourque
    Commented Nov 20 at 13:17
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Usually overheat and smoke means replacement.

Smoke is from something burning/melting usually electrical insulation.

Once the insulation is damaged it needs replacing.

Might be able to get a new motor, but probably cost close to a new drill, unless lucky.

Would contact the maker to make sure if they have replacement motors and the cost.

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    If a motor replacement is required, I'd suggest searching online for parts. I've purchased factory replacement parts from 3rd party sellers for much less than they were from the official factory web site. Also, many times, there are well made videos on how to break down the tool and do the repair. There are also many not so well made videos full of "let's try this", and "oops". While I support the "it can't be much more broke than it already is" spirit of these folk, I recommend not putting to much trust in them.
    – FreeMan
    Commented May 26, 2022 at 18:08
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What should I do if I overheated my drill motor and made it smoke?

Let it cool down in front of a fan for an hour and try using it again. If it doesn't feel right then you will quickly know.

Have I caused serious harm to the motor?

There's really no way to answer this question without taking it apart and inspecting the motor. The pre-requisite is of course that you know what you're looking for once you've disassembled it.

Is there anything I can do to ameliorate some of that harm?

What's done is done. The main thing is to let it cool down adequately before using it again. If it's warrantied then send it in for repairs.

Realistic assessment:

That drill has a 5 year warranty; I hope you registered it and can make use of the warranty.

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So you've learned what that drill's max potential is, now you have to ask yourself whether that potential satisfies your needs. If your needs exceed the drill's capabilities then the realistic question is, which drill should you buy to satisfy your needs?

If the drill is still within the store's return window then I suggest returning it; why move forward with a hobbled drill?

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  • If the drill is still within the store's return window then I suggest returning it; why move forward with a hobbled drill? Talk about unethical.
    – ron
    Commented Sep 25 at 18:49
  • @ron Why unethical?
    – MonkeyZeus
    Commented Sep 25 at 19:27
  • by that reckoning, if I buy a 2x4 piece of wood and try to jack something up with it (like my truck) and break the 2x4, then I should go return the broken 2x4 because I learned what the 2x4's max potential is? did you not read the guy's opening statement of pushed the motor too hard... bigger mixing paddles ?
    – ron
    Commented Sep 25 at 19:40
  • @ron So we're to assume that OP's guilt and my off-the-cuff remark is a reliable measurement of the drill's max operating spec?
    – MonkeyZeus
    Commented Sep 25 at 21:29
  • not sure how u read "guilt" out of the post... if you knowingly overwork the drill until it smoked then it's dishonest & unethical to return it [as defective]. If you don't have enough intelligence to not overwork the drill in the first place then i think that would be called irresponsible, and maybe stupid? If i bought said drill from you and then did what was described and came back to you with your "off-the-cuff" remark as reason to give me my money back would you?
    – ron
    Commented Sep 26 at 18:04

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