3M bristle discs

I’ve recently started using the 3M bristle discs on my flex shaft and really like them for certain applications, but find that they will not remove file marks, no matter what grit. I stack three 3/4" on a mandrel, If I have any file marks ( even #4 Swiss )or deeper scratches I need to use at least 600 grit emery paper prior to going through the 3M grits. Wondering if others have same experience?
Also, mine seem to last a long time, crazy long actually.

Hi danb4,
I use the same discs on the hard to reach/irregular shaped areas of my rings and LOVE them (though they don’t last too long on grade5 titanium and are $$$). But, I always use #8 and sometimes #10 files first.
Jeff

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Huh. For really deep scratches they don’t always work, but what you’re describing is definitely not my experience. If I have to sand first, 320 grit is generally as high as I go with it. I’m trying to figure out why that would be. You got the real 3M brand, right? Not a knockoff? I ask because I started out with a less expensive set from Amazon and while they worked fairly well, when I got ahold of a pack of Dedecos I was astounded at how much better they were. And from what I’ve heard the 3M are better still.

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I use the 3M discs a lot. I usually start with the 280 grit on file marks. They do get the file marks out, but it can take a while and sometimes seems way too slow to me. Early in my experience with the 3M discs I went after a deep mark really aggressively. I ended up with a divot in the metal. I’ve been more careful to keep the disc moving across the metal since then.

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Thanks–Yep, real 3M brand. I’ll try changing to new ones and see if that makes a difference. Mine might be used up.

I’m not sure if they are still available but I have a kit of 1" 3M radial brushes that go down to 80 grit. 120 grit is available online. Surely that would be enough to get file marks out.

What about small felt wheels or other shapes charged with bobbing compound? You’d get a smoother result than with the radials.

Neil A

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I have them and use them on occasion, but my go to is a medium grit rubber abrasive wheel. Depending on the amount of pressure you use you can remove a lot of metal or just shape and smooth the metal as a pre-polish. The wheels can be shaped with an old file, but you will never use it again as a file. I think that the Rio item number is 33263110…Rob

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Thanks, I never considered that. I’ll give it a try.

Thanks Neil. I use silicon abrasive wheels a lot (brownies and greenies), but find that they frequently leave a signature, I only use them is very small areas.

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I use and love the 3M bristle discs but they will not remove heavy scratches unless you have fine scratches which the yellow 80 grit discs will remove. I use three or four stacked depending on the application. But I use the 3M discs on 90% of my polishing needs because they can get into tight places. You need to keep the aggressive discs moving and don’t stay in one spot very long otherwise you will get grooves. I go over the area I want to polish in both directions.

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Thanks-- I put new discs on and the yellow one will remove marks from a #4 flat file. So, that explains why my discs were lasting so long :grinning:
I really love these for small and irregular surfaces. I definitely prefer the surface from emery paper for areas that are easy to get to.

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