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3M Radial disk broken from hub

I’m wondering if any of you have experienced this issue with 3m
Radial disks:

I work at a non-profit school in NH

We were pleased to save up enough money to buy a kit from Rio Grande
for 3m Bristle Disks

We have not had them long, perhaps a couple of months and they have
had very little use (since receipt of the disks we’ve run one class
per week with few students that might use the disks). Students must
check with an instructor before using them, and they are marked
regarding how to load them on the polishing wheel. The blue disk has
broken. The center hub is separated from the bristle disks - you can
hold the center hub still and rotate the bristle disks, rendering it
useless on the polishing wheel.

Our metal coordinator contacted Rio and the first question they
asked was if the disk was loaded on the polishing wheel backwards.
Since our coordinator isn’t in the classroom all the time, she said
she wasn’t sure, but knows that care is taken and that they are
marked. I’m pretty sure they were never loaded backwards. Rio told
her that they can’t be replaced and she’d need to buy a new disk.
This seems unreasonable to me - it seems to be a defect with the
wheel and I’m hesitant to have students use the others in the kit.

We are considering gluing the blue wheel, but not sure that will
work. Have others had this issue? Does anyone have suggestions
regarding how to save this disk? We’d love to continue to use these
types of disks, the students like the lack of compounds required, but
our school can’t really afford to replace them if they break so

Jean Matray
Littleton Studio School

I was told the faster you used them the quicker they broke ~ I use
mine on a cheap slow pendant drill and they last forever.

I didn’t even know they broke if on backwards I just load and go :wink:

gemheaven jewellery

Hi Jean,

Yeah, I had one of the big 6" bristle wheels come unstuck from its
hub on me too. It most emphatically wasn’t loaded backwards, or even
used all that much before it blew.

I still have it, and have been meaning to find a way to glue the hub
back together so that I can go on using it. I’m thinking that if I
put a little disk of leather on the outboard side of the bristle
stack, between the stack and the hub flange, and then compress the
hub in a vise, and glue it back together with cyanoacrylate, (super
glue) it should hold together well enough. (I’m adding the leather to
get a little bit of extra thickness inside the flange, to give a
friction grip against the bristle stack. The stack was bonded to the
hub somehow originally. (not very well, apparently.)

Hasn’t been a high priority issue, frankly. I can still use it
(gently) by putting the whole thing back together and mounting it on
the buffer. So long as I don’t bear down too hard, the bristles
don’t slip. Since those things work best when used lightly, it works
out OK.

At least with the big ones, that use the white taper-to-straight
adaptor, there’s no risk of the thing coming apart at speed, the
bristles just slip.


I learned the hard way (even though I already knew this) that high
speed generates enough heat to ruin any drill/abrasive rotary
device. Now I use my flex shaft with a foot rheostat and go slow. But
then for me, what I have is time to do the job as well as I can.


I have the big ones that slip. I wonder if a leather washer might
hold them better. What do you think? The smaller 4 inch ‘build your
own’ style work flawlessly.

Hey there,

We’re talking about two different types of radial bristle discs here
I think: small ones for pendant drills/flexible shaft machines; and
large ones for buffing/polishing machines. All rbd’s need to be run
high speed with very little pressure on the ‘bristles’. It’s the tips
of the bristles that do the work and pressing hard only compresses
them. They must also be mounted correctly so that the individual
bristles don’t tear off during use. It’s hard to describe in words,
but the curve of the bristles must follow the direction that the tool
spins at, so that the bristles ‘brush’ against the work, as opposed
to ‘stabbing’ at the work.

If, in fact, you have mounted the bristle discs correctly and used
them at the high speed with little pressure on the bristles, and used
for a very brief amount of time, it’s time to call the supplier and
explain your problem. Many suppliers in our field are good about
customer service and don’t want to sell tools and equipment that
break down before an appropriate amount of use (radial bristle discs
do wear down eventually).

Hope this is useful,
Linda Kaye-Moses

I have used these for several years and really love them. I use the
larger ones on the buffing wheel and the smaller ones occasionally on
the flex shaft. I bought them after the demo at SNAG back when 3M
used to do great demos there. The 6 inch ones that have black hubs
that unscrew are the ones that slip even with light pressure. I have
just quit using those due to the fact that I use the smaller ones on
the bufffer. I have checked the Rio site and I do not even find the 6
inch ones that unscrew, perhaps 3M does not even make those anymore.
I bought a kit at SNAG and am still using the same ones that I bought
3 years ago. The question is about the others that are not supposed
to come apart so I think you could get those replaced. The brushes
are the best thing I have ever used. I had severe allergic reaction
to polishing compounds and started using these brushes the day I
received them and have always been happy with them.