RO 90 sander jerking

[shdesign3]

I recently purchased a brand new RO 90 sander. I am removing painted surface on the window stool.Using 80 grit granat disc.  I put it in rotary mode with the speed at 4-5. The vacuum is setting in the middle.  I put my hand under the back hose and my hand on the front. With not much pressure in the front. It jerks whenever I move it.  Is this normal? or the sander have to break in?

 

[antss]

Perhaps.

  I find it can be "jerky" when in rotary mode and the entire pad is not engaged .  Like when working on a 3/4" edge. Especially with coarse grits.

There is a deceptive amount of torque generated by that sander in rotary mode.

 

[Poindexter]

Agree with antss.  And I've spent most of today with mine.  Of course, things vary based on material too.  But when rotex mode is necessary, give me speed over comfort. 

I typically turn the vacuum to a little less than 1/4 power.  And I'll turn it down lower depending on where I start to see dust.  The lower, the less jerky.

 

[Oldwood]

If you have ever ran a floor polisher it is quite like that. If you lift the back it goes one way if you push the back down it goes the other. Because of the small diameter it does not take much up and down action with your back hand. It does take some getting used to but it is a very handy sander once you get the hang of it.

 

[ear3]

It takes some balancing, but experiment with applying a little more pressure on the front, and also using the handhold/grip with your dominant hand (rather than holding it at the hose).  I usually position my non-dominant left hand so that it is cupping the front of the sander and applying pressure at perhaps a 30degree angle, rather than straight down onto the work surface. 

 

[Nat X]

For surfaces that refuse to cooperate no matter what, there's interface pads.

 

[AlexThePalex]

I put my hand under the back hose and my hand on the front. With not much pressure in the front. It jerks whenever I move it. 

This method is for when you want a smooth finish, not for the coarse rotary mode. You have to get a very firm grip on the Rotex in rotary mode, or else it will take you for a spin.

 

[antss]

"I put it in rotary mode with the speed at 4-5. The vacuum is setting in the middle. "