[Tool Time] 3M discs

Dear Tool Timers,

This weeks tool comment comes with the compliments of our own 3M
Company. If some of you folks don’t know about the 3M Co. their name
stands for Minnesota Mining & Manufacturing. They have a many
facilities right in my own back yard here in St. Paul Minnesota.
Most people think of us as living way up north and yet we always go
"up north" for vacation to Canada or Northern Minnesota.

Anyway, I received some sample radial bristle discs to try and found
they work great. Gesswein and Rio both sell them and the price is
similar from both sources. Buy em by the bag.

They look like a small polishing brush you would use on either a
flexible shaft or on the end of a small mandrel on the polishing
motor. This brush is a charged rubber and has what I would call comb
like teeth instead of solid bristles. The abrasive is all the way
through the wheel and not coated, so as the wheels get old they still
work. I found that they retain their shape well with repeated use
also. For that matter, I haven’t worn out the samples yet after
repeated use.

They come in different sizes and different colors to denote various
grits. It seems like too many grit selections, but for platinum work
the finer grit will be a great asset. The hole through the center has
two different sizes for the disc to screw on to the mandrel. This
goes into either in your flex shaft or polishing motor mandrel chuck.
I used them primarily at the bench. If you use them in the polishing
room they can screw right onto either a plastic spindle or mounted
screw mandrel.

What I found them the best for in my jewelry world is to pre polish
casting before the polishing room. They got into lots of small areas
unreachable by other abrasive wheels. In between prongs was one tight
area. I don’t like to polish with the flexible shaft because my main
bench is not exhausted and polishing compound gets in my face and I
end up breathing the compound. Now the 3M wheels still remove
material but I didn’t notice a lot of air born particles floating
around although I’m sure there were some. A small bench vent would
probably be recommended for all bench grinding, but I only have one
jewelers bench vented at my shop and it has no flexible shaft yet.
With any bench grinding or flexible shaft work please wear safety
glasses! I think most Dental Labs are set up better. The wheels left
a nice smooth matt finish ready for tripoli polishing. The tripoli
polishing went a lot faster also.

I used them both single and I also stacked them on the mandrel. I use
a quick release Faro hand piece so you need to have the 3/32nd size
mandrel. If you use the #30 hand piece mandrel size doesn’t make any

I still needed a more solid wheel to keep some of my corners sharp. I
wish all small rubber and stone grinding wheels used 3Ms’ numbered
abrasive system. Most wheels and stones I use I just guess at the
grit. With the 3M discs their color and code help a lot with choosing
the right wheel. These 3M discs will round things a bit but all in
all these are a welcome addition to my tool selection.

Thanks to Rick Phil. for the samples. Anne Hollerbach also commented
more extensively on this product a while back. It may be worth while
to look up her comments in the achieves if anyone wants more

Best Regards,

TR the Teacher,
Todd Hawkinson

I recently had a similar experience with the 3M radial bristle discs,
which I ordered after hearing them discussed on Orchid. They
immediately solved several persistent polishing problems- my work has
a lot of nooks and crannies which are difficult to prepolish. And like
Todd I noticed considerably less polishing detritus. Wonderful
product! Thanks to you folks for bringing it to my attention.

Janet Kofoed

Do you know if these wheels are micron-graded like the wonderful
abrasive sheets they make? Thanks so much for the review.

Dear Pam & All.

The 3M wheels are numbered with the lowest numbers being the
roughest. Just like their sand paper. The wheel grits I reviewed were
36X Brown, 50X Green, 80X Yellow, 120X White, P220X Red, P400X Blue,
Pumice Pink, 1 Micron Lt. Green and 6 Micron Peach. The ones I am
using the most are all in the mid range numbers. The finer numbered
like I said in my tool comments would be for fine platinum work which
I haven’t done yet. Again the selection is almost too much to choose
from but it does offer a wide range for all our diverse projects.

Best Regards,

TR the Teacher,
Todd Hawkinson

Hello Todd H.

Thanks so much for your review of the 3M radial wheels. I just
yesterday got my order from Rio. I ordered the kit with 4 different
grits. Could you clarify something for me. The kit is labeled to
contain 80X yellow, 220X red, 400X blue, and pumice pink. When I
examined the wheels, the colors all matched except there were no pink
wheels. There were white wheels, so I thought maybe the lighting was
playing tricks with the colors and the pink was so pale it looked
white. Now I see from your posting that there is really a white
wheel. Could the kit have been stocked improperly, am I developing
pink color-blindness, or what’s the deal?

The question is: how pink is the pink? Pepto-bismol pink or barely
tinged with color so that it looks white. A cursory examination of
the wheels did not reveal a number, but then they’re pretty small and
I didn’t put them under the mic. Suggestions are welcome.

Judy, in Kansas where tomorrow is the K-State spring football game
and tail-gating is the activity of the day.

Judy M. Willingham, R.S.
Extension Associate
221 Call Hall Kansas State Univerisity
Manhattan KS 66506
(785) 532-1213 FAX (785) 532-5681

Dear Judy, With reference to determining whether your white wheel is
pumice, try using it on the back side of a black onyx or other
chalcedony; if it scratches it is not pumice. Ron at Mills Gem, Los Osos, CA.

My thanks to Todd Hawkinson for giving our new 3M Radial Bristle
Discs a very favorable Tool Time Review. If anyone has questions for
the product developer please contact me directly at 3M at
@rmpihl. Questions can be directed to Rick Pihl. Comments and
suggestions will be gladly accepted. Also, many thanks to Anne
Hollerbach, who has written more about the 3M Radial Bristle Discs
than anyone. Check the archives for Anne’s postings. Rick Pihl - 3M

I will throw in my two cents. The 3M Radial Bristle Discs are simply
one of the best tools I have found for my flex shaft in years. I keep
finding all kinds of uses for them, from removing firescale and
getting into nooks and crannies. After Ann’s superb workshop on the
flexshaft, several of my students all raced to the Rio catalog and
purchased whole sets (me included).

Thank you Rick Phil.


When 3-M first developed the Radial Bristle Discs they only had 4
grits - 80X Yellow, 220X Red, 400X Blue, and Pumice Light Grey - in
the 3/4" size. Then they developed two additional sizes 1" and 9/16"
as well as other grits including - 36X Brown, 50X - green, 120X
white, 1 Micron Lt. Green and 6 Micron Peach.

Because the White and the light gray looked so much alike they
changed the light gray to pink.

Sounds like you have the old light gray pumice wheels.

The 1 Micron light green produces a great polish. Works as well on
gold as it does on Platinum. No more need of bristle brushes with
polishing compound making a mess at your bench.

Brad Simon

Dear Judy,

Doggone it I said there were too many colors and grits to choose from
with these disc. I went back and took an inventory of the samples I
was given. I did not have any of the 220x red or pumice pink to try.
I used mostly the brown, green, yellow and white colored discs. They
all worked well. Looking at the Rio catalog, their selection does not
include the 1 micron light green and the 6 micron peach (light
orange) I also received. At least in the 2000 Rio catalog. In the
Gesswein catalog they have the yellow, red, blue and gray (which I
have not heard of.) I suspect the light colored ones you have are
pumice gray. Did you get them from Gesswein? The samples I received
were directly from 3M so I can’t blame a source for any different
colors available. Good luck with your work.

Best Regards,

TR the Teacher
Todd Hawkinson

Hello Todd,

Thanks for your response. Rick Piels has graciously contacted me and
explained that the “white” wheels I got in the kit from Rio are
indeed pumice. It seems that the pumice wheel was originally a light
gray and 3M changed the color (to pink) so there would be no
confusion between the light gray and the real white wheels. Rio,
being an early distributer, did not have the pink pumice when they
put the kits together. I would not have been confused except that
the kit contents are printed in the lid (a very good idea) and list
the pink pumice. Since there was no pink, only the light gray (which
looked white)… well, anyway I was looking for clarification.

I got extra mandrels so I could have one for each color. For anyone
buying the 3M wheels, DO get enough mandrels to mount each color.
Mandrels are inexpensive and you’ll save time when switching to a
different grit!

A suggestion for Rick at 3M: provide a simple diagram as to mounting
the wheels on mandrels. On which side of the wheel does the washer
go? Show the proper direction for wheel rotation - a beginner might
put them on backward! I suspect that would be a mess.

In general, the 3M wheels are pretty slick. I love the textured
finish that can be obtained. Here’s a second to the assessment given
by Todd and others.

Judy in Kansas

Judy M. Willingham, R.S.
Extension Associate
221 Call Hall Kansas State Univerisity
Manhattan KS 66506
(785) 532-1213 FAX (785) 532-5681