Preventative maintenance brush replacement?

[cgallery]

I noticed in a manual I was reading for the Bosch table saw they they recommend annual servicing which includes replacing the table saw's brushes.

I know the brushes for some of the BT3K saws have been discontinued. Not sure which ones.

But the question is, has anyone ever replaced the brushes on their saw as a preventative maintenance measure? How old were the old brushes and how did they look when they were removed?

[Tom Slick]

you can pull them out to inspect but if they still have a fair amount left then they are still useable. IMHO they don't need replacement on time alone.

[cgallery]

My BT3000 saw is approx. 10 years old. Hard to quantify how much one uses a table saw. I guess I had thought I used it quite a bit. Hardly a week passes without working on some sort of project. It is an indoor shop, so I'm able to use it year-round (and do).

The new brushes I ordered to have on hand are approx. 5/8" long. I expected the old brushes to be worn quite a bit.

I was surprised to find that I've worn a smidgen more than 1/16" from the old brushes. So I put them back in and will continue to use them.

I also found it was easy to remove and replace them through the bottom of the saw by tilting the blade to 45-degrees.

[Turaj]

My BT3000 is about the same age as yours. On my brushes there is a line (hardly visible) 1/4 inch from the end! I was told I should change brushes when it gets to that line. I do check them as part of regular maintenance to make sure they are worn equality and I do have another set (just in case).

[cgallery]

My BT3000 is about the same age as yours. On my brushes there is a line (hardly visible) 1/4 inch from the end! I was told I should change brushes when it gets to that line. I do check them as part of regular maintenance to make sure they are worn equality and I do have another set (just in case).

So how far have yours worn?

Perhaps we should have a contest to find the most-used BT3000 saw.

I suppose minor variations in manufacturing may cause some brushes to wear faster/slower, though.

I would have checked my brushes earlier but I had read some posts from users saying that they had somehow ruined their brushes when they removed them for inspection. Then I read some posts from users that had ruined their armatures by not checking their brushes. Kinda ****ed if you do, ****ed if you don't.

And I read more posts from people that said BT3000 brushes were NLA. I got my spares from Sears.

But I'm still surprised that mine are barely worn after ten years.

[just started]

I think you will find that the people who destroyed their brushes by inspection weren't careful about orientation when they replaced them. You just have to remember to put them back in exactly the same position they come out. This is true of brushes in ANY motor or generator regardless of type or size.

[cgallery]

I think you will find that the people who destroyed their brushes by inspection weren't careful about orientation when they replaced them. You just have to remember to put them back in exactly the same position they come out. This is true of brushes in ANY motor or generator regardless of type or size.

That doesn't make sense to me. What is the difference between installing a new brush, and removing an existing brush, reversing it 180-degrees, and then reinserting it?

[just started]

That doesn't make sense to me. What is the difference between installing a new brush, and removing an existing brush, reversing it 180-degrees, and then reinserting it?

Brush holders are rarely precisely centered and exactly squared over the armature so, depending on the exact geometry in that particular motor, you can have just very narrow edge, or even a point, against the armature when the motor starts and that can cause the brush to shatter before it has a chance to wear in again.

[cgallery]

Brush holders are rarely precisely centered and exactly squared over the armature so, depending on the exact geometry in that particular motor, you can have just very narrow edge, or even a point, against the armature when the motor starts and that can cause the brush to shatter before it has a chance to wear in again.

That is a good tip, then. Due to my O-C disorder, I'm pretty careful about stuff like this and I'm pretty sure I put them back in in the exact same orientation. But perhaps if anyone ever reads this thread it would be a good reminder to take care to mark their side and orientation before removing them. And I suppose spinning the blade a little bit before turning the saw back on to make sure the motor spins freely wouldn't be a bad idea, either.

Thanks for the info.

[Turaj]

So how far have yours worn? ....

But I'm still surprised that mine are barely worn after ten years.

I have to check it next time I am cleaning the saw (probably this weekend) but I am sure I am not even half way down! (then again I have not been playing much in the shop the last two years).

On the topic of the orientation, I have never paid attention to it but I DO turn the blade by hand (saw unplugged) to make sure it rotates freely.

[Turaj]

So how far have yours worn?

Perhaps we should have a contest to find the most-used BT3000 saw.

I suppose minor variations in manufacturing may cause some brushes to wear faster/slower, though.

And I read more posts from people that said BT3000 brushes were NLA. I got my spares from Sears.

But I'm still surprised that mine are barely worn after ten years.

Well, I did have a complete clean-up this past weekend and checked and measured my brushes. They are at 9/16 (compared to 11/16 for new brushes - not going to win any "most-used" title). Keep in mind that I am a light user (specially in the past two years).