Year of brush motor ("universal motor") failures - Page 1
Forum section: electronics / projects

author: Konkedout
author_rank: Frequent Contributor
timestamp: September 27, 2025, 03:21:00 am
content: Earlier this year my Harbor Freight reciprocating saw quit. I have used it a lot since I bought it maybe 10-15 years ago, and I really like it. I still had the replacement pair of motor brushes which came with it when I bought it, so I replaced them. I then got maybe 15 -20 minutes of use out of it before it quit again. OK; one of the plastic set screws which retains a brush was broken, and maybe I did something wrong when installing the new brushes. I bought a new unit from HF.Then a month or two later our (maybe 30-40 years old?) electric knife quit. You may wonder why anyone would buy an electric knife. But it seems to be the best way to slice home made bread. We bought a new one.Just now our Cuisinart immersion blender quit. At the end of my task, it began to slow intermittently. These failure symptoms were similar in all three appliances. After cleanup I tested it and it was completely dead. We loved that thing. So much better than a normal blender. Just blend soup or apple sauce in the pot. There is much less cleanup and much less food lost in the cleanup. But holy smokes...this blender is only a few years old! We use it maybe 20x or 30x per year. I doubt that we have used it 100 times. I had hoped that it might have a brushless motor.Can anyone confirm my hunch about the motor type? Does anyone know of a good immersion blender which has a brushless motor? UNIVERSAL MOTORS (they use motor brushes) WEAR OUT!!

author: Analog Kid
author_rank: Super Contributor
timestamp: September 27, 2025, 04:26:42 am
content: Sounds like there's a problem with your electricity that's killing all your brushed motors. (Just kidding.)For comparison, I still have my Harbor Freight "Chicago Electric" (orange) sawzall which I bought for $20 in, lessee, ca. 2004. It's been used a lot and is still going strong. Much more than I expected from it.Now that I think of it, I've never had a brushed motor fail on me, and I have quite a few of them: corded drills, blender, routers, Dremels (I have replaced brushes on those) and a few others.

author: amyk
author_rank: Super Contributor
timestamp: September 27, 2025, 04:28:38 am
content: How did they fail? Do you see signs of overheating on the armature and field coils? Check your mains voltage. Besides brush wear (which is usually extremely slow), they're usually very reliable.

author: jwet
author_rank: Frequent Contributor
timestamp: September 27, 2025, 04:30:56 am
content: Play the lotto, your luck has to change...

author: Salome2
author_rank: Regular Contributor
timestamp: September 27, 2025, 04:44:20 am
content: brush motors can have a very long life when they are not abused. They fail when overloaded, causing the armature and brush holders to overheat, which causes the armature contact surfaces to deform and brushes to wear.Sounds to me like you need to be way more gentle with your appliances!

author: Konkedout
author_rank: Frequent Contributor
timestamp: September 27, 2025, 05:41:36 am
content: Yes this was the same orange "Chicago Electric" (similar concept to the original Sawzall) I remember about 40 years ago a Sawzall was about $200THEN.I wanted to cut an opening for a service door in my detached garage. I could rent a Sawzall. Instead I bought a Black and Decker jigsaw for about $15-$20 and figured that I would come out ahead if the jigsaw outlasted the project. It did and I still have it, but it is much less useful than the reciprocating saw. Mostly I use the reciprocating saw for cutting tree branches. I do a lot of that so no complaints about that one. And no complaints about the electric knife which was very old, or my 1974 JC Penney VSR drill which still works well. I am complaining only about the immersion blender, being only a few years old.

author: Konkedout
author_rank: Frequent Contributor
timestamp: September 27, 2025, 05:44:12 am
content: No, I do not think there was an issue of overheating. In the case of the blender, I WAS using it on max speed but only intermittently for a few minutes. If I do not get it working somehow I might try to disassemble it to see if I can confirm motor brushes.BTW I did confirm that the brushes in the HF reciprocating saw were worn down to nothing.

author: Haenk
author_rank: Super Contributor
timestamp: September 27, 2025, 06:06:30 am
content: Quote from: Konkedout on September 27, 2025, 03:21:00 amIt all comes down to the price - good stuff costs a good amount of money. If in doubt, buy used from a well known brand. A blender for 15 bucks from Dollar General obviously must have some "limitations" in quality, compared to a Blendtec at 500 bucks.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 27, 2025, 10:18:27 am
content: Cheap brushed motor appliances are hit-or-miss. Abused or not, they may last for a lifetime even with heavy use, or they break down in hours of use.

author: mikerj
author_rank: Super Contributor
timestamp: September 27, 2025, 11:18:54 am
content: Quote from: Konkedout on September 27, 2025, 05:41:36 amIf an immersion blender is the same as a stick blender then I'm not too surprised. These things have (necessarily) small motors relative to their power with no forced air cooling so they are run hard, and invariably built down to a price. If you want brushless then you'll almost certainly need to look at cordless models, but then you have a lithium ion battery that likely won't last as long as a set of brushes in the corded models.