3M RADIAL BRISTLE DISCS...

[ChrisL]

Those that use the 3M dremel tool radial bristle discs, other than being on the pricey side, can you comment on what you like or don't like about them here? The finest is 1 micron I see. Since the abrasive is throughout the entire bristles you can use them all the way down to the nub. Do they last a long time? What is the radius of the ones you use? Where's the cheapest place you've found them? Just some questions to start off.

Thanks

Chris L

[Del1r1um]

Those that use the 3M dremel tool radial bristle discs, other than being on the pricey side, can you comment on what you like or don't like about them here? The finest is 1 micron I see. Since the abrasive is throughout the entire bristles you can use them all the way down to the nub. Do they last a long time? What is the radius of the ones you use? Where's the cheapest place you've found them? Just some questions to start off.

Thanks

Chris L

I really like them. They can be used right down to the nub and they are very forgiving. I feel much safer getting near the edge with these than with a regular flap wheel. I use mine with a flex shaft (I don't know if I could do without that attachment) and there is very good tool response. I've used mine on two blades and I don't notice any wear yet. I have the 400 grit and the pumice grit and I got them from Cool Tools. Can't remember what the radius is. Anyways... I'm a big fan.

Oh yeah... they are modular too... they come in a pack of 5 or 6 and you pick how many you want on the mandrel. You could go really thin with just one section, or full width by loading them all on the mandrel.

[onimaru55]

G'day Chris. I use the 3/4" diameter ones in 80, 120, 240, 400 grit. I don't have much use for finer as I mostly use buffs etc after that.. Great for cleaning up tangs with out de-pinning. They seem gentler than their grit rating.
One thing I don't like is they can leave squiggly scratch marks if not kept moving evenly. I have used them on blade faces and like to keep em moving quickly from spine to edge. That way you can cut a pseudo grind pattern and then finish off with other tools of choice. They're quite aggressive on softer tempered steels but seem to be no harsher than buffs on some others. I use speeds from 5000 - 20,000 rpm on the dremel depending on the job. Don't seem to generate any excessive heat either.
They are quite durable. Had mine about 12 months. The most used 80 & 120 grits are about 50% worn but the others are near new.

Pic is of 80 grit pattern on very hard Solingen steel (rear half of blade). See what I mean about no better than a buff. Front half is hand sanded with wetndry can't remember the grit

[treydampier]

I have a question. Are you implying that these can be used as opposed to hand sanding, because hand sanding take a long time. I have done a few blades with no pitting with a steel wire brush and followed with a brass brush, but I had to go really slow and kept the blades on a wet towel. If these can be used in place of sanding, I will jump in and try them because hand sanding is the hardest part of restorations for me and I don't have a ton of time. Also, will these harm the steel in Sheffield blades? I ask because this is what I am into mostly these days.
Thanks for Putting up these items, I have never heard of them, and if they would save time I could sell my restorations cheaper.

[onimaru55]

I haven't found them a replacement for hand sanding or using flap sanders for coarser work but they are useful in certain circumstances like buffing out your hand sanding scratches etc.. There's nothing intrinsically harmful about them more about how you use them - same as anything driven by a power tool.

[ChrisL]

I haven't found them a replacement for hand sanding or using flap sanders for coarser work but they are useful in certain circumstances like buffing out your hand sanding scratches etc.. There's nothing intrinsically harmful about them more about how you use them - same as anything driven by a power tool.

The 80 grit doesn't work well at aggressively removing rusted and pitted steel? Is it because the pressure using these disc isn't much at all? I'd hope these could work well for mid grit to polish stages with really serious initial removal with hand sanding?

Chris L

[Leighton]

In my experience, nothing replaces hand sanding. Even power tools. Because power tools can leave ugly wavy patterns in the steel when held up to the light. Due to unevenness of grinding with the power tool.

These look pretty cool, if they last forever they might replace some other tools I've been using lately. If they are at all similar to what I've been using lately, the picture is exactly what you can expect out of them. ~1k grit sandpaper finish.

[onimaru55]

The 80 grit doesn't work well at aggressively removing rusted and pitted steel? Is it because the pressure using these disc isn't much at all? I'd hope these could work well for mid grit to polish stages with really serious initial removal with hand sanding?

Chris L

That about sums it up. Fine on light rust & tarnish but forget pit removal. They are not a heavy duty option & you can't apply much pressure but they will leave ugly little wavy lines if you try. What little pressure is applied goes to a very small surface.
They're quite ok if used in alternation with hand sanding or whatever means you use in mid stages but I wouldn't bother using them alone for heavy work or a mirror finish. Buffs are a better option, speaking of which these discs come in a 6" version for grinders which are likely better at rust removal. I have no experience with them to give an opinion but Bill Ellis demonstrates the larger ones on his CD.

[Leighton]

Is cool tools the only place that sells them in quantities smaller than a case? I want to try these, they sound cool.

What diameter are the ones from Cooltools? Del1r1um, do you mind measuring yours?

[ChrisL]

Is cool tools the only place that sells them in quantities smaller than a case? I want to try these, they sound cool.

What diameter are the ones from Cooltools? Del1r1um, do you mind measuring yours?

I asked Cool Tools and they got back to me yesterday. all grit sizes are the 3/4" diameter discs except for the 36 grit which is 1" diameter.

Chris L