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Fixing a Cordless Drill

17 years ago


I have a success story that I'd like to share about my DeWalt cordless drill.

It's about 5 years old and I've used it a lot, but lately it began running worse and worse and then hardly at all. Finally it would only work if I turned the spindle end and gave it a start, but then only very weakly and I could barely drill anything at all. It had lost all its power and speed.

People told me the batteries were probably shot, but if I tilted the drill straight up it ran a little faster and why would batteries do that?

So I got out my Uncle Frank's old reference book and looked up motors and stuff and it talked about brushes wearing out and commutators getting dirty or pitted after long use. So I thought maybe the brushes were worn and I would take it apart and look to see.

The instruction booklet said that there are no owner serviceable parts inside, but I took the screws out anyway and the halves of the drill came apart easily enough. At first the inside parts looked complicated, but then I figured out where the brushes were and managed to take them out. They looked fine. But when I flashed a light down into the brush holder part, the commutator did look black and dirty. Uncle Frank said it should look shiny like copper and if dirty to clean if off with fine sandpaper.

But unfortunately the brush-holder end was like held together with heavy bent metal arms. You have to bend those pieces to get it apart and I didn't know if I could do that without breaking something. But I got a screwdriver under each arm and carefully bent the metal up out of the way and slid the brushholder off the motor frame. It wasn't easy and I didn't like doing that, but it did come apart.

So then I sandpapered the commutator like the book said and made it shiny and bright again. I also cleaned the little slots in it with a tiny screwdriver like Uncle Frank said to do. Then I had to get it back together and that was the hard part. I couldn't bend back the metal arms with a pliers. Couldn't budge them. I considered boxing the parts up and sending it to DeWalt, but then decided to try one more thing. I found a small hammer and sort of tapped and gently pounded the arms back into place and it seemed good and tight when I was done.

After that it was pretty easy to reassemble the drill and screw it back together. While I was doing that I wondered if it was going to be fixed or not. I gave it 50/50 odds, but I was glad that I tried anyway even if it didn't work and I still had to send it in for repairs.

I had a charged battery right there and installed it. Lo and behold the drill ran like new with all its original power and speed! Like a brand new drill again! Amazing!

The dirty black commutator surface was the entire problem. The batteries are still perfectly good and so is everything else. I wonder how many cordless drills have been thrown away over the years as junk because of this little problem?

How come the manufacturers don't make these drills easy to service so the owner can clean a dirty commutator?

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