ETSC 125 spinning issue

[Touargei]

Made mistake of opening shell to give parts a more thorough cleaning and when put back together the sander was aggressively rotating without any random orbit.

Sander just got back from second festool service and its no better, rep didn't think sanding pad should be affecting it unless quite grooved (mine isn’t as far as I can tell). They were reluctant to service it again as they believe its acting normal, they so far replaced cushion band (which was untouched until rep suggested a loose one could be problem, I removed it and made it worse) and bearing flange.

So sander now just keeps spinning non stop, its harder to control and I wouldn’t trust it for light duty, but festool rep I last spoke to was saying it won’t always behave like new and sometimes they spin etc.

Would a new sanding pad be likely to help? Unsure how to proceed.

 

[AlexThePalex]

Your pad brake isn't properly seated on the pad. It is the rubber skirt that touches the pad. Somewhere you didn't put a part back in the right place or left a screw loose.

[attachimg=1]

We just had a little discussion about it in another thread.
https://www.festoolownersgroup.com/...with-150mm-pad/msg666925/?topicseen#msg666925

 

[Touargei]

Thanks, I did try reseating skirt but didn’t notice any difference. The machine will rotate in the way I remember if you hold it horizontally and put hand on pad. Starting to wonder if this is the way the machine is meant to work and thats why festool keep insisting its working fine (gaslighting myself). Is there a random orbit test that will be definitive?

 

[mino]

When you put on some higher grit like 180, not connect a vacuum (so the hose does not try to flip it), set speed to max and start it while on (flat) stock wooden/ply, does the sander jump around or just "travel" around.

I.e. is it possible to direct it just by the hose or by slightly guiding it around?

It is possible your sander was perfectly balanced out of factory - which created a false impression this is guaranteed - and once taken appart the seating tollerances meant it is no longer -perfectly- balanced but styill within tolerances. Every RO sander will have a tendency to rotate as that is how the forces work.

What is important is it should not rotate much - there are bearings which should provide only minimum friction to limit its "wish" to rotate so it is easy to handle by just a couple fingers or by the hose in many cases.