ROS - Embarassing Question

[Sean Kinn]

OK, so maybe I'm just unable to use a device as simple as a sander but I'd like to confirm it's just a technique issue versus a mechanical one. Up until a year ago I had primarily used 1/4 sheet finishing sanders, and of course had zero problems. I had also used a buddys 5" ROS with no problems on a few occasions. Then, I picked up a Ridgid 5" on a whim when I received an HD gift card (I hate the place and usually will only buy light bulbs, sandpaper, or other small items there).

I'm having two problems:

1. Even using 220 grit paper I'm ending up with a little trail of tiny circular scratches on the surface. I thought it was just a sign to change the paper, but it seems to be doing it even on a fresh sheet. My only hunch is that it may be caused by the underlying velcro pad (and dust adhering to it) that is sticking through some of the extra "dust holes" in the universal sandpaper I'm using. Any other thoughts?

2. It may be related to #1, but sometimes (even using higher grits of paper) It will seem to just grab hold and jerk. I've made very concerted efforts to try different holding techniques from almost letting the sander float its way across the table to applying considerable pressure.


I'd appreciate any input on this. Is my sander just a POS, out of balance/alignment, due for a pad replacement, etc? or am I doing somethign wrong. I've been able to tune up a crusty $10 #4 plane to take shavings you can read through, align my cheap TS and new BS, but this simple sander is driving me nuts.

[Jim Becker]

Are you cleaning the surface between grits? Very often, swirling can be caused by broken off pieces of the larger previous grit(s). I use a little mineral spirits on a rag to clean between grits, allowing it to evaporate before moving on to the next finer abrasive. Also, you need to be moving the sander slowly as you cover the surface.

[Bill Ragland]

Very good advice from Jim. Also when using a ROS it is not recommended to put pressure on the sander but rather let the sander float on the surface and just guide it around with your hand. Bearing down on the ROS will make the swirls much worse.

Different models of the ROS also have better or sometimes worse scratch patterns on the surface. Bosch was rated as the best a couple of years ago.

Finally, when I want a very smooth final surface I go back to the finish sander with 320 or 400 grit to finish up the surface. It removes any swirls that are left.

[Mike Vermeil]

Ditto on what Jim says - except I just blow it off.

Seems like a little grabing & jerking happens from time to time. Be extra careful when that happens to make sure there are no deep scratches left behind.

[Sean Kinn]

well, I've been giving it a swipe or two with a dust pan brush but I could be more meticulous about it. Now that you mention the "broken off" grit possibility that seems so obvious. This might be the problem, combined with the univeral paper with too many dust holes. I'll try wiping down the workpiece and vacuuming off sander pad occasionally and between grits.

Thanks...that now seems so obvious.

[Bill Huber]

I think you have got the answers you need but there is one more thing that I have found with the little tails.

Never turn the sander off while still setting on the work surface. I always pick the sand up from the work surface before I turn it off.

As Jim stated make sure you wipe the surface off before you go to the next smaller grit.

As a side note when I am sanding anything small that I can put on my sanding mat, I will use the mat, it helps the sander work better.

I also have found that if I have my vacuum connected to my Dewalt it will sand much faster and better then when I am just using it with the little collector bag on the sander.

[Rich Engelhardt]

Hello,
WOW!
I can't believe I actually know the answer to this!
Doggoneit though I can't find the jig I made to post a picture of it.

The swirls are coming from the sandpaper not being aligned 100% with the holes in the pad.
I made a simple jig out of some 3/8" dowel rods and a scrap of plywood.
I traced the hole pattern on the plywood, drilled though it and set the dowels (4 of them) into the plywood to a depth just shy of what the holes in the pad are.
To "charge" the ROS, you put a sheet on the dowels, then press the ROS down onto it. The dowels align the holes in the paper with the holes in the pad perfectly.

Much to my delight, my "swirls" vanished and the dust collection increased significantly.
It's amazing how just a tiny bit of misalignment can cause so much trouble/reduce dust pickup so much.

I'll have to go dig up the jig and take a picture of it.

Edited to add:

I found it.
(Grrrrr somebody thought it was scrap and tossed it..)
I posed a thread "Simple ROS jig" with the pics.

[Cary Swoveland]

Further to Rick's comment, I had the same problem with some sanding disks I bought that had a "universal pattern" of holes. (I think it was from Norton, but am not certain.) The paper came highly recommended, but grit became caught in the unused holes and caused the scratch pattern. I haven't seen that paper recently--don't know how it got past R&D.

Cary

[Bill Wyko]

Are you sanding unfinished wood? If not, it is most likely old finish cloging up your paper. It will typically make little dots all over your paper which can scratch the surface you are sanding.