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-   -   ROS leaving path marks (https://www.woodworkingtalk.com/f2/ros-leaving-path-marks-44214/)

RichO 10-28-2012 10:21 PM

ROS leaving path marks
 
Hi guys,

Anyone ever notice a problem with their random orbit sander's path showing up in stain?

I have a Festool ETS-150 6" sander, and I think (but not sure) that I only started noticing this with 180 grit paper.

Most of my projects are clear coated so I've never bothered going above 150 but I've done a few lately that were to be stained so I went up to 180 to remove most of the swirl marks.

After the final sanding, if you look at the piece in the right light (or after staining) you can see the long, 6 inch wide, left-to-right path that was followed with the ROS on the wood.

Any ideas on this one?

DaveTTC 10-28-2012 10:27 PM

You could try finishing with 240.

The thing I usually do is finish with hand sanding with the grain. Just a few strokes is all it takes after you have finished with ROS. Be sure there is no build up on your discs as this can leave nasty marks behind.

Dave The Turning Cowboy

DaveTTC 10-28-2012 10:32 PM

Try 240. The other thing I do is always finish with hand sanding with the grain. Just a few strokes is all it takes.


Watch out for build up on your discs, that can leave some nasties.

Dave The Turning Cowboy

CharlieC 10-29-2012 07:15 AM

I have seen this before caused by to much head pressure on the sander and/or to heavy of a grit on the paper...I dont know how old your sander is but the bearings/drive motor will get worn out and cause this problem as well.

Steve Neul 10-29-2012 07:28 AM

Something is wrong. You shouldn't be experiencing swirl marks with 180x paper. Check and see if there is something rough on the pad that may be coming through the paper. What CharlesC said is also a possibility. You may be putting too much pressure on the sander. You really shouldn't use more pressure than the weight of your hand. Excessive pressure on the ROS will slow the rpm of the sander down. Like others have said you can solve the problem by going to a finer grit but you really shouldn't need to. In this situation to get rid of the swirl marks you have if you haven't stained everything you could wet the wood with water to raise the grain and then sand with the finer grit paper. Raising the grain will make the sanding more effective.

Fred Hargis 10-29-2012 08:55 AM

I always follow up the ROS with hand sanding in the direction of the grain.

del schisler 10-29-2012 10:00 AM

Quote:

Originally Posted by RichO (Post 393314)
Hi guys,

Anyone ever notice a problem with their random orbit sander's path showing up in stain?

I have a Festool ETS-150 6" sander, and I think (but not sure) that I only started noticing this with 180 grit paper.

Most of my projects are clear coated so I've never bothered going above 150 but I've done a few lately that were to be stained so I went up to 180 to remove most of the swirl marks.

After the final sanding, if you look at the piece in the right light (or after staining) you can see the long, 6 inch wide, left-to-right path that was followed with the ROS on the wood.

Any ideas on this one?

I didn't read any other post , but i never stop at 180 grit. That is why you are seeing the mark's in the wood. i alway's stop at 400 now most will say that is to far to sand but i never have any mark's and wood is very smooth, i work up thro 220 and than 400 grit, I use lacquer also. my 2 cents also my sander is a 6"

gideon 10-29-2012 11:37 AM

I mainly use a 5" porter cable ros.

Generally, I start sanding at 120 grit and move up to 220 or 320, depending on finish.

I never use 80 and 100 as that will leave swirlies. As far as what you are dealing, I agree on build up on the sanding disks. Keep a rubber sandpaper cleaner on hand to unclog the disks. Also, maybe hand sand with same grit after the ros.

Flatlander 10-29-2012 04:35 PM

I stopped using a ROS a couple of years ago.
I now sand by hand because its faster, raises less dust, is easier on your hands and gives you a superior result/ finish.

Try it once with an open mind and time yourself for both methods.
Let's say you are doing a flat panel that was just milled as an example.

Start with 80 grit paper using a hard rubber backed sanding pad. I prefer the cheap yellow pads you can find at harbor freight for about $5.
Use a heavy weight psa paper, I have been recently using siaspeed but I started with some StGobain paper in 2 or 3" wide rolls.
Get 80,120, 150, 180,220 and perhaps 400 and 800 depending on what type of finish you are looking for.
Get some white nylon pads and a cheap paint brush.
For a trial of this you can use the hook and loop disks you use for your sander now and a block of wood cut to size As a sanding block.

Take a pencil and don't jam it into your work but cover the area you want to sand with pencil marks.
I have used charcoal pencils for this part.

Sand with the grain until the pencil marks are removed. The 80 grit session will take you the longest and it may take you two sessions to remove the mill marks.
Sometimes I shine a light to see if the mill marks are removed, other times I wet the wood to see any deep marks remain.
Use the brush to remove the dust, do not use compressed air. That will force dust into the pores and make the sawdust airborne.

Repeat for each grit sing the brush for removing the sawdust on each grit. You will notice the pencil lines disappearing faster each time you step up on the grits.

When you are done, use the white pads to remove the rest of the dust.
You will not believe the results if done properly. It's actually faster than a orbit sander and you can see and feel the difference.
The wood will actually shine!
You will not have a problem with the wood absorbing stain if you are coloring the wood.

I was a diehard power tool user before going to this method.
I bought expensive Mirka paper and good quality Bosch Sanders rated very highly.
It's a lot easier on my hands, no more tingling afterwards and no expensive dust collection systems needed.
It's much quieter, you will not damage your hearing, its faster and its less expensive to purchase and maintain.

Duane Bledsoe 10-29-2012 10:42 PM

Flatlander, where are you getting the white nylon pads? Is this an item being sold for use as something else that you are making work for this? I have no complaints with my ROS other than not being able to use it indoors, and I have a project needing finished now but weather is very bad here on the east coast, USA. I'm a outdoor woodworker since my shop doesn't have dust collection and is in my basement. So I am interested to try this for the less dust advantage. Do you just sand with back and forth movements with the grain, not in swirls?

Sorry, I don't mean to hijack a thread. Maybe the OP might need a little clarification on this too, though.

Flatlander 10-30-2012 07:25 AM

I get them at Woodcraft.

We are out of power as well in central Ct.

Flatlander 10-30-2012 07:56 AM

Sorry forgot to answer the other question,

Always sand with the grain when possible. Sometimes you can't help it because you would have such a short stroke.
Like the end grain on a raised panel..


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