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Thread: Swirl Marks

  1. #1

    Swirl Marks

    I typically have problems with swirl marks from my orbital . I use a VS Milwaukee Orbital ( 7,000 - 12,000 opm @ 3/32 orbit ) . After running my stock thru my drum sander I proceed through the grits usually starting with 80 to knock down the ridges from drum sanding then 100 , 120 , 150 and 180 . Once I feel , or rather see , that my piece is swirl free I will move on to my Ridgid 1/4 sheet finish sander ( 14,000 opm @ 1/16 orbit ) using a 180 grit paper . My final step is to hand sand with a 220 . But once those first few brush strokes of stain go on , there they are !! Not a lot but enough to get my blood to boil ! I believe my process of stepping thru the grits is acceptable and my gear is working fine but I MUST be missing something . Should I be clamping my piece down to the bench to stop any excess vibration ? Is there a technique to use to help spot swirls before the stain is applied like a damp cloth across the surface ? Slow down the Milwaukee opm before the Ridgid ? More or less down force while sanding ? I've tried so many different ways and I just can't seem to land the proper combination . HELP !!!

  2. #2
    Member
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    Perhaps you could try using 220 after the drum sander. If you find some marks use 180 then 220. I don't have 80 grit in the shop. I think the belt/disc sanders have 120 grit mounted. We have 180 to 320 grit for general use. Additionally 600, 800 and 1200 for special purposes. Also, I find that carefully clearing away all residue of coarser grits prior to moving to finer grits will provide the best results.

    bmorto1504

  3. #3
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    Napa Valley, California, USA.
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    I can think of two things to consider:

    1. Vacuum between grits. A grain of leftover 80 grit that gets caught in the sander when you're sanding with 220 will defintely leave marks.

    2. Watch for "corning"--a build-up of resin or finish that clogs the sandpaper and creates "corns"--small spots of hard material that sit "higher" than the sandpaper grit. This will also leave swirl marks.

    Bottom line: make sure everything is CLEAN when you're sanding.

    BTW--I think you can skip a couple of those sanding steps. I go from 80 (if I use it at all---I usually start with 120) to 120 to 180. You don't need (IMHO) to use every grit size.

  4. #4
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    The 1/4 sheet finish sander could be the culprit. I'm not a fan.
    Dave, from Indiana

    I am a great believer in luck. The harder I work, the more of it I seem to have.

  5. #5
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    Murfreesboro, TN, USA.
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    I agree with the 1/4 sheet sander being a suspect, although if you are seeing swirl marks, that is not it.

    I have pretty much switched to Abranet sanding pads on my ROS, and I ALWAYS use the ROS hooked to my shop vac.

    Abranet is a mesh pad with abrasive, so the dust collection is very good, and keeping dust and loose abrasive out from under the pad goes a LONG way toward eliminating swirls. I buy Abranet from 2sand.com it lasts forever and removes material rapidly.

    Last advice: a strong light shined across your part at a very low angle will show scratches and bumps very clearly before you apply stain.

    Ralph

  6. #6
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    Waynesfield, OH (ugh!) Wife won't move....
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    Ralph's suggestion of a strong light is what I do as well, works great. Sometimes I'll spay a little mineral spirits on the wood and wipe it over the surface to help. I'd check after you finish with the ROS, if it's good skip the 1/4 sheet and hand sand with the grain.

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