Swirl Marks with RO 125

lutherdail

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Joined
Feb 15, 2016
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I cannot get my RO125 to sand without leaving swirl marks, especially in the aggressive mode.  I have tried all the suggested solutions, lighter touch, making sure I progress through the grits etc.

I have spent hours trying everything.

I can't see the swirl marks until I stain it.  I don't have any issues with my DTS 400 or any other sander that I use.

Any suggestions.
 
Hi,

  Welcome to the forum!

    After using the aggressive mode I suggest backtracking one grit and switching to random orbit. Do a very thorough sanding pass with that , then move forward with your finer grits in random orbit.

    I know that some users like the aggressive mode for all the sanding right through the final finer grits. But my personal experience is that there is an increased risk of having swirl marks show through when the finish is done. I prefer to only use the aggressive mode for the first initial sanding pass and then only if I need to remove mill marks or a rough surface.

Seth
 
Use steel wool (thickness depends, I use the finer types 000 and 0000) and do a pass by hand with the grain with a light touch. To check if the swirls are gone wet with spirits and look at the wood at an angle to a light source.

Takes a few seconds and saves a lot of frustration…
 
Also, start with the highest grit possible. I rarely start below 180. Now some people don't even believe in sanding that high but I finish to 220 with any project I do. If you have rough surfaces to sand I suggest a planer or drum sander to throw them through before you start. If you have to use a low grit I firat use aggressive more than with the same grit do a few passes in orbit as I progress. I never back step I guess I haven't thought of it but as I said I rarely go below 180 and if I do it's only 150.

Another thing to consider too is that you need to clean the old grit off before moving to a higher grit. Take your vacuum with a brush and clean it thoroughly because if there is any of the low grit shrapnel behind you end up jut working it back in.

Also, I don't know about the 125 but the 150 pads edge rests on the table without the edge bumper guard on. This is also inexceptable and will scrape the piece being sanded. Always protect the edges of your pads as the pads are designed to sit flat. Also if your paper has a nick in it it will also cause swirls. This is true of any orbital sander and the steps are always the same between them. The Rotex just speeds the process up it doesn't eliminate processes.
 
Change your abrasive more frequently. 3 to 4 minutes per sheet before switching to a new sheet. Single biggest problem with sanding is overusing abrasives.

 
I've been plagued by this myself... here are my pointers.

With the Rotex 125 it is best to try and keep the unit level at all times and find a comfortable place for your hands so the machine stays stable. It is easy to apply uneven pressure which if in the fine orbiting mode can cause swirls from the pad not staying at a constant speed. That said, some woods play nicer with the sander than others. But in general let the sander do the work. I normally keep one hand on top and one hand along the front to help guide it. But I try and not apply too much physical pressure downward. The ergonomics of the Rotex are such that with the barrel diameter being quite large there is an issue of fatigue as in cases of all day sanding etc.

Another issue is the mount for the pad itself. If it is a well used and worn mount then swap it out for a new one. I mostly use the rigid mount. But in general you want to make sure the mount is flat and can spin without interference. This is the same for soft of cushioned mounts, since, these have a tendency to set the machine off balance and hence the speed of sanding will vary.

If you do find swirls between grits then step back to the previous grit before continuing. I often will do one light hand sand of the surface before moving on if I think there might be an issue. Denatured alcohol helps with seeing the swirls before applying oil. I also will do two passes the length of the piece of wood and two passes back and forth across the width. Because the nature of random orbital is to leave finer and finer swirls, meaning, the machine orbits in a circular pattern which means there are always "swirls" but they just aren't visible, so, it helps to go twice in the direction of the grain and twice across the grain to aid in the "blending" of the marks etc.

A perfectly flat surface will always give finer results than a slightly uneven surface.

Finally, if you are worried about even the smallest swirls or "pig tails" showing up during oiling, then, I have found going to 220 for large surfaces to be sufficient. I start at 120 if the material is planed and jump to 220 directly. For smaller surfaces I sometimes go higher. But going higher will increase the possibility of seeing swirls. I also found that in some cases after oiling you can use the sheep skin buffer or something similar to help knock down the sheen on a difficult surface. This also makes it harder to see any minor swirls. But that always bugs me knowing they are there!

Good luck!

 
Turning the dust collector down, or allowing a vacuum leak if using a shop vac, will lessen the pressure on the material.
 
I LOVE this video. But honestly this a perfect example someone who knows exactly what they are doing and has done it a LOT, making a it look easy.

If you watch the video closely, he uses several techniques for controlling the sander and not letting the sander control him. Pay attention to where and how he grips the Rotex to keep it flat during the sanding operation. If you look closely he changes his stance a bit when he starts sanding. He seems to widen his stance giving him a more stable platform. He keeps his elbows in closer to his torso and moves his body more to guide the sander. That keeps the sander from lifting on edge and creating a swirl or gouge. He has a standard pattern for sanding that he is consistent with; right to left and up and down.

The other thing to notice is that this is a 12 inch by 12 inch piece of wood. He doesn't have to move his feet to get across a 5 or 6 foot table top. You really need to pay close attention to technique especially with these very aggressive sanders.

Ron
 
Thank you for the responses.  I will definately try it. 

Mccooley, you really got specific enough to give me some new things to try.

I am using red oak that in most cases has been run through a surface planer.  What grit would you recommend starting at. I was using 80 a lot of times. Maybe that is too course?

Also I get different opinions on what speed to go at.  Is there a point where I can be going too slow?

I have been going with the grain only, thinking that might help reduce swirls.  Your post is the first I have heard suggesting also go against the grain. I will definately try that tonight

Also, for red oak how fine a grit do I need to get to to make the swirls invisible.  Maybe I am just being too fussy. I just don't remember ever having so much issue with swirls except for this particular sander

 
lutherdail said:
...
I am using red oak that in most cases has been run through a surface planer.  What grit would you recommend starting at. I was using 80 a lot of times. Maybe that is too course?
...

If 180 is too fine, then 150 or 120.
I use 180 on a lot of wood from a planner, and the sander quickly starts cutting into the choppy waves.
Sometimes I just use 240.
 
Learn how to use a scraper card and or cabinet scraper well and you will sand a lot less :)    Shouldn't need more than one grit that way...and it's a lot quieter!
 
Christopher Robinson said:
Learn how to use a scraper card and or cabinet scraper well and you will sand a lot less :)    Shouldn't need more than one grit that way...and it's a lot quieter!

Do Festool make them?
 
What are the product numbers for the polish and wool polisher and orange sponge for a 5" sander?
 
[member=15289]Birdhunter[/member]
The list is at the end of the PDF file [member=44099]Cheese[/member] posted above.  Thanks Cheese for posting that!

Mike A.
 
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