Questions about the brushes on my TS 75 Circular Saw ????

[Frank Pellow]

The warrenty on my TS 75 EQ saw ran out two months ago, and last week the saw just stopped at lerast a dozen times.  After a rest of about 5 minutes it always started again.  But, then after about another 5 minutes of running, it would stop again.  Today, I was unable to start it at all.  [sad]  I tried things like changing the plug-it cord and switching power sources, but nothing helped. 

My guess is that the problem is the brushes and that task of changing is something that I ought to be able to manage.  I often work in remote locations and so, for me, being able to do simple maintenance is a necessity.

Here is a picture of the motor with the cover removed and the connectors to the brushes removed:

[attachimg=#]

and it looks to me like the graphite on the brush pointed to with the arrow has worn down to the point where it should be replaced.

I have two questions?

1. Can someone confirm (or deny) that this is likely to be the problem?

2. It tried to gently pull out one of the brushes using a pair of needle nose pliers and it wiggled but resisted comming out.  Is there some "trick" to pulling out the brushes?

 

[Michael_MA]

[attachimg=#]Hello Frank,

depending on your number of service hours, this could most likely be the reason for the saw to stop its operation.
just took my TS55 apart and had a look on my brush holder assembly, which seems to be locked with two Torx screws (one is already missing on your picture - did you remove it ?)
I'm attaching a picture, how my assembly looks like, maybe this helps a little to claifiy the problem. The green circles show my brushes and the screw which secures the assembly.[attachthumb=#]

kind regards, Mike

 

[Frank Pellow]

Yes Michael, I removed the screws.  Once removed, I expected the brush assemblies to come out easily.  They do wiggle, but it appears that I might need to give them a heck if a yank to get them out. 

 

[Michael_MA]

well, since the brushes are spring loaded, you might have to unload the springs first , before you can remove the assembly.. let me see how this is done on my TS55.
I could remove mine by gently pulling on the connector of the assemblyw with pliers and then using a small screw driver in the window wher you can see the spring to put additional force in the direction away from the spindle while pulling it all out..

hth..

Kind regards, Mike

 

[Frank Pellow]

Thanks Michael, that worked. [thanks]

Here is a photo of the brushes after I removed them:

[attachimg=#1]

But, to me, there still seems to be sufficient graphite on the brushes.

Can anyone tell me one way or another whether the amount of graphite left on the brush to the left would cause a problem?

If that is not the problem, I would like to hear suggestions about what else I can check to find out why my saw will not start. 

 

[Michael_MA]

Just as a quick shot Frank, could you extend the spring pressure a little by holding the brush in its mount with a screw driver and gently pull the spring in the windows about 1 or 2 turns in the opposite direction.. before you mount them back into the saw.. if the saw still does not want to start, there might be something with the heat/overload protection circuit, which may have shut off the machine... hopefully not..

Good luck !
kind regards, Mike

 

[CharlesWilson]

Frank,

It looks like the spring on the left isn't pushing the brush out as far as the one on the right. Maybe something in the holder is binding, so the left brush isn't making solid contact with the commutator.

Charles

 

[Rick Christopherson]

Frank, your brushes are not warn to the point of shutting down the saw, but it does appear that the brush housing is deformed enough to stop the brushes from extending. Without anything holding them back, the carbon portion of the brush should extend all the way out, as shown below, and also in your own right-hand picture.

Your brushes DO need to be replaced, but because they are not sliding properly. When a Festool brush is warn out, there is a spring loaded pin that gets released that is designed to cut power to the motor before damage to the commutator can occur.

[attachimg=#]

 

[Rick Christopherson]

By the way Frank, if memory serves me, reinstalling the brushes on a TS55/75 is kind of difficult. You are already committed to replacing them, so before you install the new ones, I would practice installing the old ones first (but don't run the saw...they are damaged). I can't remember why I suggest this, but doing so will reveal to you any problems that may arise, without damaging a new set.

 

[Alaska Ranger]

What on earth could get to the motor's innards in order to deform the brush housing? ??? ??? ???

 

[Frank Pellow]

Frank,

It looks like the spring on the left isn't pushing the brush out as far as the one on the right. Maybe something in the holder is binding, so the left brush isn't making solid contact with the commutator.

Charles

Thanks Charles, I should have noticed that.  I will try to see what is holding back that spring.

 

[Frank Pellow]

Frank, your brushes are not warn to the point of shutting down the saw, but it does appear that the brush housing is deformed enough to stop the brushes from extending. Without anything holding them back, the carbon portion of the brush should extend all the way out, as shown below, and also in your own right-hand picture.

Your brushes DO need to be replaced, but because they are not sliding properly. When a Festool brush is warn out, there is a spring loaded pin that gets released that is designed to cut power to the motor before damage to the commutator can occur.

Rick, thanks for the picture and the advise.

 

[Frank Pellow]

What on earth could get to the motor's innards in order to deform the brush housing? ??? ??? ???

That's a very good question, a question that I was asking myself after reading Rick's reply and before reading your's.  And not only what?, also how?

 

[Frank Pellow]

By the way Frank, if memory serves me, reinstalling the brushes on a TS55/75 is kind of difficult. You are already committed to replacing them, so before you install the new ones, I would practice installing the old ones first (but don't run the saw...they are damaged). I can't remember why I suggest this, but doing so will reveal to you any problems that may arise, without damaging a new set.

After "fixing" the spring as suggested by Charles, I put the brushes back and I found them to be very easy to insert (after moving a wire or two).  I was going to try to run it but am now having second thoughts because of your warning.  Surely just trying start the saw with the brushes back in place, won't to any damage, will it?

 

[Michael_MA]

In my earlier life, when motors were more heavy and Brushes were not that easy to reach, i fixed quite a few on appliances by uninstalling - verifying - and re-installing the brushes if i found them to be sufficient.. So, dont get scared to put your brushes back in your Saw as long as these three conditins are met:

1.) The brushes are long enaugh, which means at least 1/3 or better 1/2 of the assembly window is covered with the graphite of the brushes and have smooth surfaces (scratches --> defective collector)
2.) Every Brush is freely moveable within the assembly and there is enaugh spring tension to press the Brush gently in place.
3.) You haven't flipped both brushes while re-installing them.. otherwise you will have some more brush fire and will smell some Ozon for the first operatiing hours.

kind regards, Mike

 

[Rick Christopherson]

By the way Frank, if memory serves me, reinstalling the brushes on a TS55/75 is kind of difficult. You are already committed to replacing them, so before you install the new ones, I would practice installing the old ones first (but don't run the saw...they are damaged). I can't remember why I suggest this, but doing so will reveal to you any problems that may arise, without damaging a new set.

After "fixing" the spring as suggested by Charles, I put the brushes back and I found them to be very easy to insert (after moving a wire or two).  I was going to try to run it but am now having second thoughts because of your warning.  Surely just trying start the saw with the brushes back in place, won't to any damage, will it?

Frank, if you think you have successfully straightened out the deformed housing that was preventing the brush from sliding freely, then you would be fine to try running the saw. Sorry if you misunderstood. There wasn't a significant risk of damaging the saw if the brush was deformed. You will notice significant arching when the saw is first started, but this should diminish with time (don't know how much though). If it doesn't go away, then consider replacing the brushes with new.

As for the original cause (if this was the main problem) it is possible that sawdust got into the housing and prevented the brush from sliding freely. The deformation could have been the result of removing the brush from the motor.

 

[Frank Pellow]

Thanks Michael and Rick.   After reading your advise, I went ahead and tried the saw and it now works.   [thumbs up]

I did bend the housing a bit on one of the brushes when I removed it but the metal is quite plyable and it was easy to straighten.

So the problem in the first place, was that something  ??? caused the spring in one brush to become deformed and to stop pushing properly against the graphite.  When I straightened out the spring, I found nothing at all that looked suspicious.

The bottom line is that I now have a working saw against thanks to the help of members of this forum!  [big grin]

 

[Kevin D.]

Glad to hear Frank.  I'm just steppin out the door now, and sorry I forgot to reply that it would have been OK to borrow mine.  Totally been packin' all day.  I think the boats gonna sink once we load it up.  [scared]

 

[ScotF]

This post was very informative.  I do have a question on service life of the brushes in general -- does anyone know how many hours of operation a typical brush will last?  I know with some other tools I own that the manual states to check the brushes after X hours of use and I was just curious what others have experienced with Festool.

Thanks!

Scot

 

[greg mann]

Scot,

I do believe that Frank has changed the brushes in his Rotex. He will chime in, I am sure. I think the answer to your question is: Quite a long time. I suspect the Rotex would be a higher brush wear tool simply because of run-time. Saws and Routers probably run less, except for in a router table, but most of the time the router is not under load but waiting for us to make our passes.