Rotex 125 Help

[rjbuilder]

Just bought a Rotex 125 and am having trouble getting it to run smoothly.  Seems like it just wants to bounce around.  I'm using it with a Fein vac.  COuld it be getting too much suction?  Any help would be appreciated.

 

[Forrest Anderson]

Just bought a Rotex 125 and am having trouble getting it to run smoothly.  Seems like it just wants to bounce around.  I'm using it with a Fein vac.  COuld it be getting too much suction?  Any help would be appreciated.

I see this is your first post, so welcome to the Festool Owners Group!

Does the bouncing happen in Rotex rotary mode or random eccentric mode?

You certainly might want try altering the suction somehow on the Fein (which I believe doesn't have an electronic suction control), and you also might want to try changing the speed of the Rotex (make sure to try it at maximum speed in random eccentric mode), and experimenting with the downward pressure you are applying to the sander.

You are not the first to complain about the RO125 not running as smoothly as expected, and by total co-incidence I was reading such a thread before you posted - check outhttp://festoolownersgroup.com/index.php?topic=1246.0 where a new owner said "Bought a Rotex 125 recently... In rotary mode, it works like a charm and is a viable belt sander replacement...  In RO mode, the sander is difficult to control and chatters badly".

You might be able to find other threads about bouncing, jumping or chattering Rotex sanders by using the search function.

Forrest

 

[Ned]

Welcome to FOG, rjbuilder.

I think what Forrest has mentioned, and the thread he pointed you to, probably will be the biggest help, but here's something else to consider:  Festools run better after a break-in period.  It's more noticeable with the small sanders like the RTS 400, but your new Rotex probably needs a bit of running in.  Ten hours of use should loosen it up just a bit.

Ned

 

[bruegf]

Mine seems to run smoother when I have the vac turned down to about half speed.  You might need to add a valve on a tee between your vac and your hose so you can allow some extra air in to reduce the vacuum.

Fred

 

[Zaphod]

I started the cited thread regarding my RO125 problems.  I had problems with chattering and bouncing out of the box in  random orbital mode.  I was initially skeptical, but a few hours of run time does help dramatically.  David G. from Festool recommended the soft pad to minimize chatter in R.O. mode; it made a tangible difference.  My understanding is that the standard pad is firmer to withstand the heat from rotary mode and is less than optimal for random orbital mode.  Best results in R.O. mode are achieved by running at max speed.  Even so, it won't be confused with a dedicated R.O. sander.  I purchased an ETS125 for finish sanding; it lighter, smoother, and quieter than the Rotex 125 for it's intended application.  I was initially 'on the fence' regarding the RO125 but am glad I kept it.  As mentioned previously; it's akin to a belt sander in rotary mode and quite reasonable in R.O. mode after a few hours of use.  Too much vacuum can be a problem; temporarily disconnect the vacuum for comparison. 

 

[Warrior]

rj,

I have a Rotex150 and brand new it jumped around quite a bit in Random Orbit mode. It now runs very smooth. I think that in random mode you deffinately will need to lower suction some how.

Eiji

 

[bill-e]

I doubt it's suction.  I can run my 125 full suction with my CT33 and it's very smooth.  My guess would be that either the pad isn't installed properly or is bad.  Remove the pad and reinstall it and see if that helps.

 

[Eli]

With the 150 it could be suction (I lower mine lots sometimes), but I think the grip has to do with it as well. It's one of those things I didn't hold right at first.

 

[bijeshj]

I purchased a rotex125 a few weeks ago, had a difficult time with it jumping all over the place. But between playing around with speeds, more experience and possibly the 125 improving after the run in period it has become better. I had issues with both modes. The 125 is hooked to a ridgid vac. 

 

[Dan Clermont]

This is gonna sound kinda strange but works on  my RO-150.

When it wobbles turn the handle 90 degrees. For example, if you are sanding a frame and panel door and have the handle parallel to the stiles while you sand it will wobble. Turn the handle so it is perpendicular and it won't

A friend of mine (who also posts on this forum from time to time) with a RO-125 discovered that awhile back and it works for me.

I always run mine on maximum suction

Dan Clermont

 

[Dave Ronyak]

I have had an RO 125 nearly 3 years.  When I have experienced "jumping" I have done as Dan suggests and this often cures the problem.  I have also tried changing vacuum settings, but this does not seem to make much difference for me.  I also try changing the speed, and this often cures the problem.  Assuming you are not already running maximum speed, try both higher and lower speeds and use what works best.  A frequent cause of "jumping" when sanding off an old finish is caused by melting and resolidification of the old finish on the surface of the workpiece and on the abrasive disk.  IF I try to use too high a speed when sanding off old varnish over shellac, the local spots of the disk load up with little swirls (they look like little curved tadpoles) of congealed finish.  When they are on the disk, the sander will jump around, no matter what the speed setting or vacuum setting.  My solution is not a perfect one, but it helps a lot for me: Turn down the speed of the sander, and frequently remove the sander from the workpiece, invert it, and scrape/pop off those little tadpoles with a scraper.  If you are careful, you can do it with the RO running on low speed, but this obviously can be dangerous, especially so because while you are contacting the disk with the scraper, the turning disk is sharpening your scraper to a knife's edge!!  But it works for me.  I used this technique to remove the old varnish over shellac finish from several mahogany interior doors that I needed to save and reuse.  I had to scrape the disk every minute or so of use, but the "tadpoles" popped off easily and quickly.  Got a very sharp scraper from this job, too.

Dave R.

 

[Brice Burrell]

  I think the biggest issue here is not holding the sander perfectly flat. With a smallish sanding surface and long body with the vac hose on the end it is easy to inadvertently hold the sander on a slight angle. RO150 owner's have less of a problem with this because of its larger sanding surface, the larger surface is easier to hold flat. Like the others have said, a little practice and some experimenting with different speeds/suction you'll get the hang of it. Good luck.

 

[Don Bullock]

  I think the biggest issue here is not holding the sander perfectly flat. ...

I think Brice has the right idea here. If I concentrate on holding my RO125 flat I don't have any problems with it jumping around. It takes some effort, but once I got used to the sander I'm very pleased with how it performs. The RO125 is a fantastic tool!

 

[rjbuilder]

Thanks for all of the suggestions.  I put a T on the Fein shop vac that I used to adjust the suction by slightly opening the cap on the side that the hose was not attached to and it seemed to help.  Will keep plugging away but seems like it is getting better.

 

[wikki]

I to have had this problem so to the point that I sent it back to festool.  I got it back and still the same problem but not quite as bad. Now I use the new BOSCH I just purchase for all my finish sanding 125 is now relegated to prep work.

 

[Greg_R]

I had the same problem and learned that I was using the sander incorrectly.  If you are applying ANY downward pressure then it will hop around.  Use a very light touch and let the weight of the machine and the paper do their work. 

 

[imaginarynumber]

I find that my 125 jumps too much if I lower the speed when using 400g titan II to sand latex primed mdf.

To get around the problem I use an interface pad- this also helps to prevent the paper clogging.