Festool ETS 125 EQ jumping

[Ben Hatcher]

I was using my Festool ETS 125 5" random orbit sander with 220 grit brilliant 2 paper to sand drywall the other day. It was not a joy to use in the least. It jumped all over the place. I had to press towards one side to get it to settle down. That doesn't seem normal to me. It settled down once the paper wore down a bit, but give me a break! That can't be normal. I tried to remove some finish from a table I'm redoing. On the parts where most of the finish is gone it is fine. On the parts with finish, more jumping jacks. It is boarderline rediculous. Am I doing something wrong here?

[Roger Jensen]

I find jumping is related to the roughness of the surface. Does it get better after you have taken the first layer of the finish? Have you tried with a more coarse paper for the first pass?

[Ben Hatcher]

It almost seems like the paper is sticking to the material and the rotation is so tight that it is easier to spin the tool than the disk.

[Chris Padilla]

Try turning down the strength of the vacuum. With a smooth surface and smoothish sandpaper, you are fighting the suction.

[Ben Hatcher]

Interesting thought, Chris. I'll give that a try when I get home. Thanks!

[Roger Jensen]

I thought of that too, but I don't see why the jumping would change with used paper if it was caused by suction pressure.

BTW - I don't have a variable speed vac so I had to hack something together to allow me to reduce the vacuum pressure on my Festool 150. Do you have a Festool vac or have you done something to enable reduced suction? I'm not real happy with my solution.

Roger

[Chris Padilla]

Roger,

I'm not totally sure but often, when I use 220+ grit sandpaper, it tends to build up stuff on it rather than actually wear down but it depends on what you are using it for. In that case, the sand paper will ride on the build-up thus alleviating the suction issue a bit.

Another thought is that the friction between the sandpaper and the surface being sanded is decreased over time as dust builds up on the sandpaper.

[johnny means]

Jumping common is a occurence with the Festool sanders. It is due to too much suction. Of course we all knew this already because we read the manual:rolleyes:, which let us all know that we need to dial down the vac speed for sanding. Of course, this doesn't work for those who haven't sipped enough of the Kool-Aid.

[Greg Portland]

BTW - I don't have a variable speed vac so I had to hack something together to allow me to reduce the vacuum pressure on my Festool 150.Get a Y-branch + 2 caps that are the size of your hose. Plug in the hose to one branch of the Y and the cap on the other branch. Drill a 1/4" hole in the cap. Test the sander for jumping; if there are still problems, continue to enlarge the hole until it is fixed. Use the other cap (with no hole) for maximum vacuum when using other tools. I have seen owners of Fein vacs use this exact method.

The sander is particularly prone to jumping with finer grit paper (as you've seen). Turning off the vacuum is a quick test before you go through all the trouble of hacking your vacuum.

[Ben Hatcher]

I tried the sander with no vac and it still jumps all over the place. There's about 5 wonderful minutes in the life of each disk where it is worn down slightly but not clogged where it doesn't jump. I expected more from a $170 sander and saw no mention of the jumping before I bought the tool. I can't be the only one who's annoyed by this.

[Joe Leigh]

Something is not right. I have the same setup that I use for finish sanding with 180-200 grit and the sander is silky smooth. If the vac setting is too high there is resistance too movement, like the sander is stuck to the wood, which it is, but the sander is never "jumpy".

[Jeff Monson]

An ETS should not be jumpy at all, especially with 220 paper. I'd try Bob Marino and see if he can help you out, he is a top notch guy and a great festool dealer.

[Greg Portland]

I tried the sander with no vac and it still jumps all over the place. There's about 5 wonderful minutes in the life of each disk where it is worn down slightly but not clogged where it doesn't jump. I expected more from a $170 sander and saw no mention of the jumping before I bought the tool. I can't be the only one who's annoyed by this.
OK, now we've eliminated vacuum settings.

Sanding drywall on a vertical surface is adding other variables that we want to eliminate while trying to solve your problem. I agree that the sander should work for this application but since we're trying to resolve the problem let's start with the basics.

What is your technique? Most people who come from other sanders (PC, Dewalt, etc.) are used to pushing the sander down into the workpiece. This is NOT how you want to use the Festool. You want the weight of the sander to do ALL the work. If you push down on the sander it will jump around + it will not allow the paper to work properly. Try some 80 grit rubin paper on a piece of scrap wood and see if your are getting any jumping around. You should be able to lightly hold the sander with just your fingertips and move it around the workpiece with zero jumping or effort. If that does not work then I would guess that your sander has a problem. Go to the dealer you bought it from and have them take a look. You could also try their floor model and see if it behaves in the same manner.

[Ben Hatcher]

Thanks to all of your for your help. It looks like the issue was a combination of vac setting, the paper, and the shellac getting gummy from the heat.

I switched to crystal paper and that seemed to handle the shellac much better. Once I got to bare wood, it performed as expected. I played with the vac setting a bit more and found that I could duplicate the jumpy behavior even on bare wood, so I'm very glad to know about this little trick.

Thanks again. I suppose I should have read the instructions.