RO 150 Sanding Scratches When In RO Mode

[guddeco]

I am finding that even after I turn down my CT36 and balance the RO150 and apply as little pressure as possible, I'm still getting sanding scratches in the RO mode.  Can anyone help me fix this issue?

 

[Administrator_JSVN]

What's your grit progression? How long do you sand at each grit? What's your sanding technique, in other words how do you move the sander over the surface?

 

[semenza]

I am finding that even after I turn down my CT36 and balance the RO150 and apply as little pressure as possible, I'm still getting sanding scratches in the RO mode.  Can anyone help me fix this issue?

Just for clarity ..... RO as in random orbit or RO as in Rotex?

Seth

 

[guddeco]

Sorry, I did mean Random Orbit when I said RO mode.  I start with 60, 80, 100, 120, 150, 180, 220, 320. Always putting as little pressure as possible. Try to do 1 second per inch when sanding move with the grain down the length, then move across grain down the length, then sometimes I will make circles down, but depends on my grit. 

 

[tbellemare]

Do you start with the sander on the work? Do you end with it off the work?

Tom

 

[guddeco]

I don't start with it on, but end with it off.

 

[tbellemare]

You might be getting some gouging when you start. It's hard to hit the work cleanly with the sander already powered up.

Tom

 

[semenza]

If you are starting with 60 it may just be that the coarse grit marks are  not getting sanded out thoroughly as you go higher. 60 and even 80 can leave some pretty deep marks.

Seth

 

[guddeco]

If you are starting with 60 it may just be that the coarse grit marks are  not getting sanded out thoroughly as you go higher. 60 and even 80 can leave some pretty deep marks.

Seth

Okay, thanks for the replies! I'll see if I can start at 80 and work up. A lot of what I work with is rough so that's why the 60, but when it's not so rough, no need to start that low I suppose!

 

[semenza]

If you are starting with 60 it may just be that the coarse grit marks are  not getting sanded out thoroughly as you go higher. 60 and even 80 can leave some pretty deep marks.

Seth

Okay, thanks for the replies! I'll see if I can start at 80 and work up. A lot of what I work with is rough so that's why the 60, but when it's not so rough, no need to start that low I suppose!

  Try wiping with mineral spirits or using a light to show the scratch pattern as a way to check that the previous grit has been sanded out as you go up the scale.

Seth

 

[tjbnwi]

Try the gear drive mode. It really does work.

Tom

 

[roblg3]

I can second to make sure to wipe the piece between grits.  Small pieces that you don't see can be left behind keeping a larger grit on the piece as you move higher in the progression.  Its like leaving a pebble between the sander and the piece leaving scratches of low grit in your high grit sanded piece.

 

[es07Eric]

I seem to be achieving similar results with "swirls". 

After my recent acquisition of the RO 150, it has been my go to sander. 

I recently helped a friend sand the some clear 8/4 maple after he was disappointed with the results of his sander; it had left what I can best describe as "pig tails" or curly Qs.  I opened my big mouth and told him that I could achieve a "swirl free" finish.  I felt confident, especially after watching that video with Larry that Shane posted. 

Long story short, I worked the surface using Granat paper starting with 80 grit and progressed with 120, 180, 220 and did so using ONLY the coarse/gear/Rotex mode. 

While I did what I set out to do, which was achieve a "swirl free" finish, I was left with what I can best describe as very fine large 150mm-ish parenthesis.  The wood top looked like this:

((((((((((((((((((((((((
))))))))))))))))))))))))
((((((((((((((((((((((((
))))))))))))))))))))))))

In my thread about my recent Kapex Miter Station build, I was able to achieve very good results, however, I believe it has more to do with the fact that I continued the progression of grits past 220 and then to 320, 400, 800, then Festool's MPA-5000 w/the orang pad and finished off with the sheepskin.

While I feel fairly confident with the above, there will be times where I would like to stop sanding at 220 for a natural finish or matte poly finish.

Should I be using the random orbit/fine mode in the same grit after the coarse mode?  Should I be using my ETS 150/3 or ETS 125 to make the final pass?

Oh, and yes, a Festool CT was used and was used on very low respective settings to the grit.  Also, it was wiped down between grits and even did so as I switched papers of the same grit.  I also was not at all stingy with the paper, there were even times that I replaced the paper and the used paper appeared and felt sharp!

Thanks everyone!

Cheers,
Eric

 

[gippy]

I must be old fashioned I guess. I made some nice sanding blocks that take a 1/4 sheet of paper. My last pass is hand sanding with the grain to remove any swirl marks. Doesn't take very long to do.

 

[Rick Christopherson]

Long story short, I worked the surface using Granat paper starting with 80 grit and progressed with 120, 180, 220 and did so using ONLY the coarse/gear/Rotex mode. 

This is something I have noticed in many of these discussions, but why did you begin sanding at 80 grit? Unless you have some serious leveling to do, this is way too coarse, especially in Rotex mode. Even with minor leveling, 120 grit in Rotex mode is plenty coarse. If no leveling is required (i.e. single board with no joint) then 120 grit in RO mode is sufficient to start.

 

[tjbnwi]

I agree with Rick, unless the surface dictates using a coarse paper start finer. I've prep some material for stain/finish using only 220 to get some handling marks out of it.

tom

 

[roblg3]

Tom, I'm very surprised to hear you sanding to 220.  I've always been told never above 180 because it burnishes wood and makes applying stain tricky?  Is that a standard for you to do 220?