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Thread: losing my mind over sanding swirls

  1. #1
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    losing my mind over sanding swirls

    Please read before diagnosing... I have watched so many instructional videos, read so many threads and magazine articles, and continue to experience ongoing struggles with "swirls" or "pig tails" after sanding my projects. I thought explaining my current approach might help the crew here give me some ideas as to what to try next.

    Let's suppose I'm building a table top:

    - After rough lumber has acclimated to my shop and has been surfaced/prepared

    - As I clamp/glue, I use shop-made cauls to help ensure close alignment between the edges of each board

    - An hour after clamp/glue, I carefully/gently scrape squeeze out on both sides of the table (I find that glue is easy to remove this way.. I temporarily move a clamp, scrape that area, replace the clamp for overnight, and so on...)

    - The next day, after clamps are removed, I use a combination of card scrapers and hand planes to blend joints as needed. This typically results in a surface that has only minor imperfections that I can detect with my fingers.

    - For large surfaces (e.g. a dining table top) I then get busy sanding using my larger sander which is a Bosch 6" ROS, model ROS65VC-6. I usually run it on speed 5 or 6 (which are faster settings on this tool).

    - I begin around 100 grit and progress to mid-200's, never skipping a grit along the way. I have tried multiple types of Aluminum Oxide discs.

    - I progress about 1 linear inch in about 5 seconds, with the grain, overlapping passes, and the sanding disc sitting flat (not tipped). I typically do 2 such passes per section before incrementing to the next overlapping section. To give you an idea, to sand my current table top (measures 3.5 feet wide x 7.5 feet long), it took me about 2 full, non-stop hours to progress through the grits.

    - I have good vacuum suction pulling through the sander the entire time for all grits

    - I brush the surface clean each time I change grits

    - In terms of downwards pressure, I am barely pushing downwards at all... Just enough pressure to keep control and guide the sander. The disc spins freely across the surface and I am not bearing down aggressively.

    - I have changed the pad on the sander, and also tried a much softer pad.


    After all of this, and without fail, I find widespread swirls across my work. Sometimes what I would consider "very noticeable" and other times "probably only noticeable to a woodworker". I either choose to live with it at that point or spend hours and hours and hours (literally 5-6 hours) painstakingly trying anything under the sun to resolve the issues (more card scraping work, hand sanding, endless power sanding with 300 grit, etc.).


    As two points of reference:
    - As a much less-experienced woodworker, I used an old Porter Cable 5" ROS and took none of the care noted above to achieve flawless results (even when judged by my current eye)

    - For smaller pieces, I use my smaller BOSCH ROS20VSC and follow all the same steps as noted above.... and get swirls galore.



    At this point, I really must wonder:
    - Am I missing something extremely obvious?

    - Are my expectations out of line? That is, should I expect that it truly takes every woodworker 10+ hours to sand a table top?

    - Is it possible that 6 different brands of sand paper are all a problem? Is alum oxide not an ok choice?

    - Are my Bosch sanders to blame? (I am 150% willing to write a check right this minute to buy 2 new Festool sanders [or whatever the group thinks is best] if that will help me past this issue)


    I'm open to anything.. I'll even video tape me working on a table top if that would help. I'm going absolutely mad over this

    Thanks!!

    Bob R.
    - Bob R.
    Collegeville PA (30 minutes west of Philly)

  2. #2
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    Why sand after hand planing? If you do a good job of planing, then sanding cannot come near the finish. This is my usual go-to.

    When I do sand, I go to 400 grit with Abranet on a Mirka Ceros or very old Festo (forerunner of the Festool 150/3). If there are any swirls (not usually), I would use a card scraper or hand sand with the grain.

    Regards from Perth

    Derek

  3. #3
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    I agree with Derek after handplaning a surface I will sometimes go over the surface with 400 grit that
    I rub with the grain. You don’t mention what wood your working with closed grading hardmaple or open red oak. My suggestion sand with the grain when get to 220 raise the grain with water and grind it smooth again.
    Good Luck
    Aj

  4. #4
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    Bob, you are not alone. Because most woodworkers on this forum work in isolation, they are their own worse critics, and do not have a solid concept of "good enough". In my hand plane courage thread almost all admitted to sandpaper. And yes, after sandpaper, I can still see "defects". I suspect your table is fine.

  5. #5
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    Try 320.,,

  6. #6
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    Quote Originally Posted by Tom M King View Post
    Try 320.,,
    Our switch to a belt sander which will only sand in line with the grain.
    Lee Schierer
    USNA '71
    Go Navy!

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  7. #7
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    It's hard not to have to do a little hand sanding if you want something perfect.
    Attached Images Attached Images
    Last edited by Tom M King; 08-04-2022 at 12:45 PM.

  8. #8
    My guess is that the table top isn't terribly flat even after hand-planing, and that the ROS is snagging the high spots causing those swirls. Check for flatness using a long straightedge.

    I recently finished a dining table where I had to a good amount of cross-grain flattening with my biggest plane (5-1/2), and then with-the-grain planing and scraping to get it ready for sanding. My cheap 5" Makita ROS then didn't leave any swirls.

  9. #9
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    Turn the vacuum pull down if you are using a vacuum. If not, the follow up with hand sanding.
    Bumbling forward into the unknown.

  10. #10
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    Depending on the finish being used, I dont know that a purely planed surface is the 'best' surface. I would double check that against my planned finish schedule, but yeah, a planed surface finish is preferable to many in terms of aesthetics. I dont know that it is preferred by contemporary finish manufacturers.

    Bob, my first instinct is to say "its the sander", but lets not jump to spending your money too quickly. You mention multiple types of abrasives, what brand specifically? Is your sander connected to a variable suction vacuum?

    If i had to guess, i would say you are not sanding away the original 80-100 grit swirls. By the time you make it to 220+ its already too late, and you would be there for 5 hours trying to sand out the 80 grit swirls. Your sander has a very small stroke(2mm), which means its not that aggressive at removing material. Conversely, it should be less likely to have big noticeable pigtails. They will still be there, but tighter packed and less noticeable. My guess is you are damaging the surface with the coarse grit that your sander cannot adequately remove as you step up into the grits. I see this with my Festool rotex switching to my Festool ETS ec. The 3mm stroke ETS cannot undo the swirl pattern off the aggressive rotex in a reasonable amount of time. I would go back to the basics and lay down a light pencil hatch across your surface. Sand till there is no more pencil. Repeat the pencil hatch. Change grits and sand. Rinse/repeat.

    I can all but guarantee a new Mirka/Festool sander would solve your issues. If they dont, then send the sucker back for a refund within the trial period.

  11. #11
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    Thanks everyone!

    Brian - do you mean to try reducing the shop vac suction a bit? I was just now reading that some felt that too much suction could result in swirls.


    I also read some suggestions to start at a higher grit (say, 150 grit rather than 100 that I start at now). My table tops have been nice and flat (the cauls help a lot on that).


    Here, from left to right are 4 recent efforts that all had the "swirl battle"... Ash, Hickory, Pine, Walnut. My current table top I'm working on is actually just poplar, but had the same issue.

    ash top table 3.jpg hickory table 2.jpg pine top table 3.jpg puppy crate 4.jpg
    - Bob R.
    Collegeville PA (30 minutes west of Philly)

  12. #12
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    I have both those sanders and neither leaves swirl marks, so save your money on thinking new ones are the solution. The thing that really caught my eye in your work description is that you move the sander "1 linear inch in about 5 seconds". Really? That's incredibly slow. No wonder you are having problems, especially with the coarser grits. I would typically move about 12" in 5 seconds. You also said you move with the grain. When sanding a big table top I almost always start going directly across the grain, then diagonally, first one way, then the other, and then with the grain. I do that through 80 grit, then switch to sanding only with the grain. On rough glue ups I've started with 36 grit in order to get the top flat, then 60, 80, etc. up to whatever the final grit is. I almost never hand sand. That's how good I think the Bosch ROS65VC-6 is. I do not use a vacuum hookup with it, just the onboard dust cannister.

    I did this tabletop from a biscuit aligned glue up at my friend's house. I used a #6 handplane to get the joints fairly flush and then spent 2 hours to sand it flat, as you see it. I started with 36 grit and followed the sequence above up to 150 grit. I used a hard pad on the sander.



    John

  13. #13
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    Quote Originally Posted by Bob Riefer View Post
    Brian - do you mean to try reducing the shop vac suction a bit? I was just now reading that some felt that too much suction could result in swirls.
    It's a good idea to reduce the vacuum air flow more and more as you get up to finer grits simply because there's less space between the "grains of abrasive" which in turn can make the sander "stick" to the workpiece. That can cause issues and may make any swirling worse. Make sure you are also thoroughly cleaning the workpiece between sanding grits to avoid a "bigger" piece of broken away grit from getting caught on the new, finer abrasive and causing the swirls. If you do see them...carefully inspect the abrasive pad that's on the sander. You will likely fine something; either debris or "corn" where some wood fiber got "glued" to the abrasive and is now cutting patterns in your fresh wood surface.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  14. #14
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    My only suggestion is to wipe down with mineral spirits after you believe that you have removed of the previous grit and are ready for the next grit. This will highlight any swirl marks.

    This will help determine where in the process you start seeing the marks.

  15. #15
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    I agree with Patrick about using a pencil to draw a light cross hatch pattern and sand until it’s gone. Do that every grit. Clean thoroughly between grits. Inspect the results every grit. It’s nearly impossible to remove 80grit scratches with 220 paper.
    Steve Jenkins, McKinney, TX. 469 742-9694
    Always use the word "impossible" with extreme caution

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