Is it my brushes?

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Forum topic by Craftsman on the lake posted 03-28-2015 08:59 PM 938 views 0 times favorited 9 replies Add to Favorites Watch
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Craftsman on the lake

2794 posts in 3459 days

03-28-2015 08:59 PM

Topic tags/keywords: sander bosch bosch sander brushes sander repair question

My Bosch ROS sander that I’ve had a few years and put a fair number of miles on it has suddenly started acting strangely. When I start it at full speed it is a bit slower and when I put it to wood it has very little power. Sometimes after several minutes it will gain power and act normal and sometimes it does and then becomes anemic again.

I’ve never replaced the brushes. They are fairly inexpensive on Amazon. Am I correct in assuming that maybe the brushes need replacing? Anyone experience these symptoms before? I do love this sander. It does a great job an has virtually no vibration. You can sand for an hour and your hand doesn’t feel like your skin is going to fall off like some other sanders I’ve had in the past.


-- The smell of wood, coffee in the cup, the wife let's me do my thing, the lake is peaceful.

9 replies so far

View ChefHDAN's profile


1067 posts in 2871 days

#1 posted 03-28-2015 09:39 PM

Peeking at this parts diagram It looks very simple with probbably a molded plastic plug retaining the brushes. I’d say for $9 in parts its worth trying. And thank you for the comment about the bosch, I’ve about killed my Dewalt and it numbs my hand after about 20 minutes even with anti-vibe gloves.

-- I've decided 1 mistake is really 2 opportunities to learn.. learn how to fix it... and learn how to not repeat it

View intjonmiller's profile


20 posts in 1843 days

#2 posted 03-28-2015 09:40 PM

Sounds like brushes to me. I’m not an expert there, but I’ve changed out a few brushes in a few tools. If it’s a matter of power it’s usually the brushes or the speed controller. You’re not going to hurt it by changing the brushes and it’s a good chance to dig in and see if anything else needs work, and cleaning while you’re at it. The rubber band style belt that prevents it from spinning freely when not against the workpiece is another common part to replace, and very cheap.

View NoThanks's profile


798 posts in 1550 days

#3 posted 03-28-2015 09:54 PM

First thing you need to do is take them out and look at them. You should know right away if they are bad.

-- Because I'm gone, that's why!

View MrUnix's profile


6757 posts in 2220 days

#4 posted 03-28-2015 09:57 PM

First thing you need to do is take them out and look at them. You should know right away if they are bad.

Exactly what I was going to suggest… Worn brushes don’t usually cause loss of power, but it could be contributing to some other causes and they are easy to check.


-- Brad in FL - In Dog I trust... everything else is questionable

View ElChe's profile


630 posts in 1358 days

#5 posted 03-29-2015 03:31 PM

Does it smell funny when you use it? I’m wondering if it is the armature and if so then toss it. If it’s the brushes pretty simple to replace although I’ve had more than one spring loaded brush shot out of a tool like a tiny little cannon.

-- Tom - Measure twice cut once. Then measure again. Curse. Fudge.

View robscastle's profile (online now)


5070 posts in 2225 days

#6 posted 04-10-2015 10:11 PM

Hello Daniel,

You may find its the eccentric bearing within the sole plate of your sander

I had a similar situation with mine, and its easy enough to check, just remove the screws from the base and pull off the plate.
Item 28 on the diagram appears to be the bearing flange assembly
You can test the bearing and see if there is any roughness in it while its apart no problem.
I am not sure from the diagram if you can actually run it with the bearing out.
Wiggle the fan around and if there is excessive sideways movement do not run it!
Otherwise carefully test run it facing up and see if there is a difference.
Brushes as you indicated may also be a problem, if you have Compressed air give the ROS a good blow out fine sawdust is very cruel to the sander and it can gum up bearings as well as brushes.

It may pay to do this first as no disassembly is required !
Worn brushes are usually indicated by more than normal sparking and usually just the one does it.
Excessive sparking, meaning a ring of sparks around the communtator indicates a shorted windings somewhere.

-- Regards Rob

View distrbd's profile


2252 posts in 2468 days

#7 posted 04-10-2015 11:56 PM

blow some compressed air around the switch and see if it makes a difference,it did with mine.

-- Ken from Ontario, Canada

View Craftsman on the lake's profile

Craftsman on the lake

2794 posts in 3459 days

#8 posted 04-11-2015 12:16 AM

Thanks guys.. when I took it apart, the brushes looked good even though I had ordered a pair of new ones. I blew out the sander all over and when I put it back together it seemed to work like normal. Just dirty I guess.

-- The smell of wood, coffee in the cup, the wife let's me do my thing, the lake is peaceful.

View Mustang67's profile


111 posts in 1575 days

#9 posted 04-11-2015 12:50 AM

That’s the way my Dremel acted and replacing the brushes worked.

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