RO150 - is it me or....?

[Stevenski]

I have been using my RO150 for the first time in quite a while and the darn thing seems to have a mind of its own and wants to go off in all directions and frequently starts jumping and kicking like a bucking bronco!

I have tried changing out the abrasive paper, using various speeds, light pressure/heavy pressure/no pressure at all, adjusting power on the vac, horizontal sanding, vertical sanding.....

Do you think that there is something wring with it (eg bearing)? Or is it user error?
I don't recall it rehang like this last time I used it.

Thanks for any advice/input

 

[peter halle]

It can get used to especially if in the rotary mode. how rough is your workpiece. Changing grain and low & high spots can cause what you have been experiencing.

Peter

 

[Stevenski]

how rough is your workpiece. Changing grain and low & high spots can cause what you have been experiencing.

tada! I think we have a winner

Thank you Peter for asking that question because this is probably the cause. I'm making some slatted benches and the surface in question is a glue up of around 15 battens which - despite best efforts - is in fact quite uneven and has a lot of variation. The side panels in the photo. That's exactly what I broke out the RO150 in the first place - to flatten it in coarse mode (which it did beautifully, by the way)

I'll do a test on a flat board and see if the issue disappears...

 

[onocoffee]

In my experience, with both the RO150 and Bosch GET75-6N, that jumping issue never truly disappears. But it usually jumps against the grain (or so I've convinced myself). I typically pull it off and get back on with from a different direction - but I haven't used it on slatted panels like you're working on.

 

[Stevenski]

it usually jumps against the grain (or so I've convinced myself).

could definitely be part of the problem here, also

in my experience, ....that jumping issue never truly disappears..

well that's sad news - put me right off my morning coffee

 

[Crazyraceguy]

The first thing I would do is go with a lower grit abrasive. (notice I didn't even ask where you started)
The point of flattening something like that is to take the tops off of the ridges as quickly as possible.
As it gets flatter/smoother, the machine will calm down considerably.
Adding the front handle can also improve the handling, especially early on, in the lower grits.
Try some 40 grit Granat or Rubin2. If it's really bad, there's 24 grit Saphir.
It does take some work to remove these marks later, but that end grain requires more effort, in the first place.

 

[Stevenski]

My problem was clearly a result of varying heights and grain directions.
My test on a flat board confirmed it - my RO 150 was gliding over it as smoothly and lightly as you could possibly wish.

Thank you all for your input. It was all very relevant and on point