Resurrect a Burnt Cordless Drill

I have two cordless drills. One that was dumped at work and another one that I bought at a flea market.  Both had their motors burnt and smell like so.  So I tried something radical: replace the dc motor.  But were to find one alike?

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Step 1: Secrets of the Elders!

I will reveal my secrets of material sourcing.  There is a guy that lives in the city's dump (very common in Mexico) and has an army of people looking thru junk to find stuff tha might be worth money.  So on sundays, he deploys his load of junk on the road, so costumers go through all of it to find useful stuff. I like the old saying "one man's junk is another's treasure".

Step 2: This Is the Key!

Find yourself one of those a handy-dandy tire inflators (new ones sell for  8 USD at autozone).  But I found two junky ones for 3 USD.

Step 3: The Quintessential Part!

This is what you need, the motors of this small air compressors and the 12 V dc cordless drills are exactly the same.  Remove it from the cylinder unit.

Step 4: Take the Pinion Out.

The pinion on the motor needs to be removed as it is not the same size of the one on your cordless drill.  Use your prefered techinque.  I use electric pliers clamped in a bench top clamp as a suport for the pinion, then use a screw the same size of the shaft to pop the pinion out.  Suit yourself!

Step 5: Dissasemeble

Remove the motor from the gear reducer and desolder the wires.  Repeat the previous step to remove the pinion.

Step 6: Put the Right Pinion

The pinions are different sizes, so be careful on the one that belongs to which one.  This picture shows it better.  Just put the right pinion in the new motor. Do it GENTLY, be careful not to damage the motor. 

Step 7: Rassemble the Motor to the Gear Reducer.

Reattach the motor to the gear reducer.

Step 8: Solder and Reassemble.

Solder the wires.  And put everything back in place.  Watch for wires not to be trapped.

Step 9: Voila!

This two babies were resurrected ann you can notice that I attached lead acid batteries to them.  While they might be hevier (one gets used to that, plus is like working out at the gym!), they are powerful.

So there you have it, junk stuff put to good use once more!

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    15 Discussions


    5 years ago on Step 9

    you give cheap solution but great for earth...!


    8 years ago on Step 9

    I think your pictures and instructions represent your hobby in an admirable way!!!
    Ya just got'a like junk to share the hobby...Much Thanks !

    1 reply

    9 years ago on Step 9

    nice one! i got one of those compressors its crap as a compressor.just got to kill one of my drills,ha ha

    3 replies

    Reply 9 years ago on Step 9

    Thanks! Those compressors do work, it just takes a while to inflate a flat tire, but it helps if u lift your car with a jack.


    8 years ago on Introduction

    That suggestion reminds me of something i did with a cordless drill and its rechargeable 18 V battery that wouldn't recharge. I don't use it a lot and the battery would self discharge and eventually became useless. These drills can be purchased for around $30.00 or less at a yard sale (with probably a dead battery).

    At the top of the battery case there are four or six long screws. Remove them and the top comes off. There are 15 NICD (or sometimes NImh) batteries inside. Gently remove them. There are a couple in the long top part that goes into the drill or charger. You can leave them in, but disconnect them. Find and identify the + and - wires that go to the contacts and bring them out (solder extensions if necessary).

    Go to Radio Shack and get three 4-cell AA adapters. Also get three clips with wires (or you can just solder them together) to connect in series. Load up the adapters with 12 AA Alkaline batteries. You will be able to just fit them into the cavity where the original batteries were located. You still have 18Volts. Put the top back on the case and plug it into the drill. DO NOT EVER PLUG IT INTO THE CHARGER AGAIN EVER. IF YOU ARE DARING, YOU MIGHT TRY IT OUTSIDE AND UNDER A METAL PAIL, BUT IT WILL PROBABLY EXPLODE.

    The drill should operate well, and the batteries will not self-discharge. If it slows down over time just open up the battery case and replace the batteries. Why go to this trouble? A replacement or rebuilt rechargeable battery may cost much more than the original drill was worth. I was quoted $80.00. A 16-pack of AA will cost around $9.00. The adapters will be another $10.00 or so. NOTE: If it is one of the 19.2V types (16 rechargeables) you can remove and squeeze in another AA battery in the plug. An extra .3V shouldn't hurt anything.

    BTW: There were only a couple of unrechargeable batteries in the pack, so i salvaged the rest to re-battery some very old Solar Lamps.


    9 years ago on Introduction

    Holy cow dude! I thought I was the king of saving, finding, repairing and reusing. You win! I've got a cordless dremel that's going to fully die soon. I know what to do there, but I don't think I would have thought to replace the motor in a drill. Actually I've never seen one with a burnt motor. It's always the batteries dying. Got that figured out if anyone has been searching.

    Next I'd suggest, see if the junk man has a camera upgrade for you.

    Thanks for another great idea.

    4 replies

    hmmmm.... if it is a dremel you might be better of simply replacing the brushes, way cheaper. Depending on the model it may be designed to make this easy.

    Well, the most common ones that I've came across were Black&Decker, Makita, Dewalt, and some chinese ones and they all have the same motor size so they are compatible with the one I replace. Never seen a Dremel. But thanks for your post

    Ya, cordless dremel with a broken variable speed wheel. Actually the wheel is fine, it's just the varistor or whatever it is. It's either on 10k rpm or off! Works though and the battery is in great shape. Also needing new brushes too. It was given to me in this condition so I can't complain. I've used the crap out of my corded dremel and it's still in top shape.

    Tanks a lot for your interest! Yeah my photos are crappy, 'cause I used a crappy Nokia 3200 mobile phone I bought there too! just 50 cents for it. As for the batteries: I used discarded Lead-acid ones from work (we have several KUKA robots that use them).So I bring those home and feed them thru a pulsing DC supply that seems to desulfate them. The drill becomes havier, but one gets used to it. But when I grab a cordless drill at work, It feels strange, so I took one of mine to the shop where I work, so It feels ok there too.


    Reply 9 years ago on Step 9

    Thanks!  By the way, I guess that after electronics and mechanics, reusing junk is my favorite hobby.