ETS 125 ROS stalling, sputtering

[cbehnke]

I've had my ETS125 ROS for about a year and it has received very light hobby use.  maybe a total of 6-8 hours of sanding time on it.  Recently I've noticed upon start up and sometimes in the middle of sanding that it does something that is a mix of stalling/pausing where the random orbit action almost completely stops and then anywhere from 1-5 seconds later it starts sputterring and regaining movement/momentum and gets back to normal.

I'm running it with a festool mini,  just doing basic sanding work of things like cutting boards, lazy susans, etc.  my planer leaves a decent finish so most of the time I can start at 150 or 180 grit on my projects and i work up to 400 grit.  I rarely use it with a 60 or 80 grit disc for aggressive material removal.  I use a relatively light grip and almost no downward pressure, i'm not mashing it down on the surface.

I've checked the power cord connection to the ROS and the mini and the mini to the wall...no issues there.

Any ideas or thoughts on what it might be?  Thanks for any input.

 

[AlexThePalex]

Sounds like an electrical problem. It could be caused by the plug-it cord not making a good connection with the tool. Do you have any other cords around to try out? I have had this problem too and it was the cord.

 

[mouppe]

I can confirm what Alex said. My ETS 125 did the same thing recently. I noticed that I could make it happen by moving the plug-it end (the ETS end, not the vac end). I changed cables and the problem went away.

 

[cbehnke]

guy's thanks for the advice.  checked it on different outlets...the issue remains. don't have another power cord so I can't try that. 

so I removed the sanding base to see if there were any issues.  none seen, clean inside, and when I powered it on for a few seconds without the base, no stall issue, ran fine. so I remounted the sanding base.  I started it up and the issue was back.  

I began to suspect the braking pad was causing too much drag on the sanding pad.   I lifted up the soft rubber braking pad so it wasn't touching the sanding base and I powered it back on.  It ran normal.  Then while it was on, I released the rubber brake pad, allowing it to return to its normal position where it touches the sanding base....and the stalling issue returned.

So it seems the braking pad is creating enough friction to keep the sanding pad from rotating.  The brake pad is such flimsy, thin rubber...it just doesn't seem like it could stall the motor, but what do I know.

Is the braking pad the issue?  Or is the fact that the pad can stop the motor indicative of something wrong with the motor?

any thoughts appreciated.

 

[Theshipstore]

I would suggests calling Festool Service, the number is in the Sander. Its possible it might need to go back for a service if this is the problem. Lester in service is a great guy and will help you Thur this issue

Sal

 

[AlexThePalex]

Judging by what you report here I'd say your right to suspect the pad brake. Even though it may look flimsy, the pad brake is designed to stall the pad. When it's gone, the sanding pad will spin wildly out of control. Sounds like the pad brake is doing its job a bit too well now.

The pad brake is designed to wear over time. If your pad brake is the problem by causing too much friction, you must speed up the wearing process a bit so it won't cause too much friction anymore like it does now.

It is also a known fact for these type of Festool sanders that they need a break in period to let the brushes seat properly. Until the brushes are seated properly, the sander will not work with full power. In fact, the power can be reduced by almost half. I suggest you hang the sander by a rope and let it run for a couple of hours (up to 8 hours) to break it in. This will seat the brushes and it will also wear the pad brake. Don't worry about the long run time, the sander can take that. You do have to be sure that under these circumstances, the sander won't stall 100%. That would be very bad.

You can also try to use sandpaper on the pad brake to wear it a tiny bit. Or perhaps use some lubricant (haven't tried this myself, use at your own discretion).

If all else fails, you could order a new pad brake from Festool.  

 

[cbehnke]

bedankt voor de hulp Alex.

 

[cbehnke]

Quick Version:
Figured it out.  It was a bearing that sits under the brass counterweight that was binding up and not rotating freely or the counterweight and the metal disc it sits on were binding up.  I cleaned the bearing and disc and bearing surfaces, oiled it, worked it free, and the sander is working fine now.

Detailed Version:
I spoke with Festool CS when the problem first occurred but I had no detailed info to focus them where the issue may be.  After fiddling with the sander and coming up with the base brake information (see earlier in the thread), I called CS again to discuss options.  I spoke with David.  He ran me through a few questions to try to figure it out.  He came up with the problem likely being the bearing that sits under the brass counter weight, nested in the silver metal disc.  

The silver disc needs to spin freely and easy, spinning for a few seconds with just the flick of a finger.  From taking the sanding base off and checking things out, I knew it wasn't spinning at all.  David asked if I did some recent refinishing work, wondering if some of the removed paint/finish product was causing the bearing to bind up.  YES, I had!!!  Right before the problem started I had put some stain on a project, didn't like how it was turning out, so I worked it off with my sander.  I know the stain in the wood was likely NOT fully dried/cured before I removed it.  Then another light went on....I mentioned that when I was removing the stain, unbeknownst to me, my vac hose had a dime sized hole in it, so it was not removing waste from the sander as effectively as it should have.

We surmised it was a combination of factors that caused the problem; the not fully dried stain combined with improper waste removal likely led to a situation where the stain product caused the bearing to bind/stick or some sticking together of the surfaces of the metal disc and the counterweight.  

I cleaned the bearing, disc and counterweight, put some high speed machine lubricating oil on the bearing and slowly worked it in (2-3 minutes) until the silver disc was spinning completely free of the counterweight.  I fired up the sander and it worked as it should.

Problem seems to be solved.

Thanks David.

 

[jmarkflesher]

David, I have an old Bosch 3725 DVS sitting idle for the same reason. After reading your post I oiled the bearing until it worked freely. Seemed to be white paint residue at bearing. Works great now. Thanks, MARK