Quick check of a Sanding Drill

[Brian Kent]

It goes back and forth from working and then not at all. Then before I threw it away it worked again.

I have time to check something quickly by not to learn small electric motor maintenance. It is the Harbor Freight / Chicago Electric "3/8 in. Heavy Duty Professional Magnesium Variable Speed Reversible Close Quarters Drill With Keyless Chuck"

I'll open it up, dust it off. Is there anything I can check quickly?

[Ken Fitzgerald]

If it has brushes, they might be broken or the spring over compressed.

Some drills have 2 small removable caps covering the brushes. You simply remove/unscrew the cap, and pull the brush out.

Handle them with a little care as they are made of carbon and somewhat brittle.

[Fred Belknap]

I don't have that brand but occasionally I have to blow the dust out. Just use an air hose and blow in the vent slots. Ounce the forward/reverse switch got bumped into a neutral position.

[David DeCristoforo]

Anything with a name like that is bound to give you fits...

[John K Jordan]

It goes back and forth from working and then not at all.

An electrical problem like that is sometimes very easy to fix. Sometimes a bad connection. Sometimes dust in the switch. Sometimes whacking it with a mallet fixes it.

I would definitely take it apart, blow out the dust, and inspect each connector of each wire for looseness. (Grab each crimped and push-on connector and see if it is loose anywhere.) Look at the brushes as mentioned, clean the commutator. Use an ohm meter/continuity tester to be sure the switch functions flawlessly. The switch is often the problem. Bad solder joints are occasionally a problem in cheaper things. Check the continuity in the cord - the wire can break inside at the plug or at the tool and it can work intermittently depending on how the cord is flexed. (Flex it while plugged in with the trigger pressed and see if it runs and quits.)

Only do the following if you are comfortable working with 110v since it's easy to die or at least make some sparks and fire if you do something wrong: you can apply power while apart and trace the voltage from the plug to the motor.

JKJ

[Brian Kent]

Anything with a name like that is bound to give you fits...

Yes, and the bizarro thing was that it lasted 3 years where the Neiko lasted 1.

[Joe Bradshaw]

Brian, I have one of the HF right angle drills that I have been using for about 7 or 8 yrs. I also have several of the Neikos. I usually wear out the gear train before the motor goes. You have been given good trouble shooting advice. If you keep 2 drills on hand, the one you are using will be afraid to quit, because it knows that you have a replacement. With the HF coupons and a service agreement, You will be set for a long time.
Joe

[Mark Greenbaum]

Probably the brushes. There may have been an extra set with it when you purchased, so find them and replace if needed. If you can't find them and they're worn out - GOOD LUCK trying to get replacements. I searched for months to find some for my HF electric chainsaw to no avail. Nobody has the size needed, not even carbonbrush.com, and they list everything.

[John K Jordan]

...brushes... If you can't find them and they're worn out - GOOD LUCK trying to get replacements.

Depending on the design, you can usually take slightly larger carbon brushes made to fit something else and easily file them to fit.

JKJ

[Brian Kent]

Well I opened 'er up and blew off the connections, but was actually quite surprised. It was pretty dust free inside. There is still a lot of life on the brushes. Joe, thank you for mentioning the service agreement. I may have bought one. Now to find it.

As of this moment it is working.

[Brice Rogers]

Brian, I had a 90 degree HF angle grinder that was exhibiting symptoms like yours. I used to hit it with a dead blow hammer and it would start working again. I did that for a couple of years I think and then it stopped completely. When I took it apart I found the the three power wires were electrically connected with machine screws that pressed them against a conductive strip. Turns out that one of the screws was loose. Since then (about 10 or 15 years) it has kept on ticking. It came with a spare set of brushes that had long since disappeared.

I'm not saying that your problem is the same as mine. But perhaps try wiggling the cord (especially where it goes into the drill) when it stops working. Or wack it with a dead blow

[Bob Bergstrom]

Anything with a name like that is bound to give you fits...

I think he just described our Chicago politicians? Might work, doesn't work, election time work, election over stop working. Yep, that about sums it up. Wish we could throw some away also!

[Brian Kent]

Bob, the whacks with a dead blow hammer are not an option. Too old-school Chicago.

[David C. Roseman]

Brian, I had a 90 degree HF angle grinder that was exhibiting symptoms like yours. I used to hit it with a dead blow hammer and it would start working again. [snip]

Well done! Reminds me of Andy Griffith's trick in "No Time for Sergeants". He got the radio working by whacking it with his hand. But he spit in it first.
https://www.youtube.com/watch?v=U2fSw0ua5K0

[John K Jordan]

Turns out that one of the screws was loose.

I find that most problems like this are poor connections - cold solder joints, bad crimps, the loose screw you mentioned, and corrosion in the connection.

One thing I started doing years ago is using a bit of dielectric grease on every electrical contact connection. (Available at any auto parts store, HD, etc.) This is especially important in automotive and other applications where the environmental conditions are variable, but I use it on almost anything that relies on a contact between two pieces of metal. It keeps air and moisture away from the contact point and minimizes or eliminates the possibility of corrosion.

JKJ