This may seem like an odd question, but how does one know when its time to change the brushes on various tools? Many tools promote the fact that the “brushes are accessible”. I`ve had triggers go on tools, cords split and frey…but Im not sure Ive ever needed to replace the brushes. Any tools Ive ever had die on me were either as old as the hills and I was happy to upgrade or they werent the quality tool I believed I had purchased, so I wouldnt waste the time changing the brushes even had I known that was the problem. Is it a gradual thing that Ill notice? How does I know?
J. D. Reynolds
Home Improvements
“DO IT RIGHT, DO IT ONCE”
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I checked the brushes on my miter saw thinking it may be the cause of my saw not operating(turned out to be the switch). Anyway when I checked the brushes there was just a spring behind them which keeps them in contact with the armature. they did not seem to be worn much (saw is about 4 yrs old).
so I would assume that when the motor stops runing when the brushes are wore out.
BT
I've had brushes wear out over the years and the symptoms weren't always the same.
On tools where the brushes or the armature was partially exposed, like on a Skil 77, there was some heavier sparking activity for awhile prior to failure. On the DC motors on my sawmill (Woodmizer) they started becoming intermittent in their response to the power switch. And other tools, without warning the tool just suddenly quit working.
If your tools are used around a lot of dust or grit, like around masonry or drywall, or if they're stored in a damp environment, you can expect shorter brush life (along with other motor parts) and it's a good idea to clean the tool more frequently and check the brushes more often.
I've kind of informally gotten in the habit of checking the brushes on most of my more heavily used tools. On most tools they're pretty easy to remove and inspect. My DC motors are a bit more difficult because I've got to partially disassemble the motor.
And occasionally, the brush won't be worn, but the spring will be broken or the little braided cable will be broken in which case, you're going to need to replace the brushes anyway (replace both).
If you're very organized (not me) it's a good idea to catalog your brush numbers and/or keep spares for high use equipment, because sometimes it's difficult for a supplier to get replacements if it's an older tool and you don't have part numbers.
I've been wondering the same. The manual that came with my Milwaukee jigsaw recommends brush replacement after one year(!). They can't be serious...
Only happened with me three times on differant tools, and suddenly too, similar symtoms like nothman pointed out, burn't smell. The worst brush change was a makita palm sander, a pain in the ####.
Peace Pot Microdot
Rather than simple wear, most woodworking tool brush failures are due to low contact pressure due to dirt (sawdust, etl al) causing the brush to stick in the holder. Low contact pressure = arcing which greatly accelerates wear. Simply removing brushes occasionally and cleaning area - pressureized air fine - helps. On skil products in particular, I take the brushes out and give one light slide of each side down a file which helps prevents future sticking.
Some brushes have a limiter on them so they wont wear to the point where the springs damage the commutator. The tool just stops working. So do you. then after you put new plug-ends on you ext cor and a new switch in and check the breaker. you realize that the brushes are gone and replace them.Do not try this at home!
I am a trained professional!
Check those brushes. An old toothbrush, an old 2" paintbrush, a can of compressed air and an old pair of socks all help. One sock and the brushes are used to clean the vents, around the brush covers and the brush track. The canned air, IMHO, is more controllable and less likely to damage the commutator when blowing away crud than the hose from a compressor. If you are working in dusty or especially sandy areas check those brushes, the ones on the tool, more frequently and give them a good cleaning. I could swear I once saw a hammerdrill smile after I cleaned it up.
How short to let them get before replacing? Whatever the manual says but realize that they wear faster when dirty, damp and under heavy loads. When in doubt replace. Better to waste a set of $6 brushes than a $200 tool.
That second sock? Cut the toe out and slip it around the vents on that drill before you crawl under the house. It keeps most of the sand out of the power tool. Remove it before using the tool.
Can you believe that I actually read the instruction book for the Makita 4 1/2" grinder I just bought and their brushes have a mark on them that tells you it's time to replace.