CBN wheels: no dust but a lot of metal particles

[Sergio Villa]

Hello, I recently mounted a eight inch 80 grit CBN wheel on my seven inch Baldor. Of course I had to remove the protective screen and guards. The result is not so satisfactory. It is true that it grinds true and faster and without dust, but the metal particles are everywhere. I now have to use protective glasses after risking some iron particles in my eyes.
The surprising thing is that nobody that I know mentions this problem which could be a safety issue besides a messy problem. Metal particles and ball bearings do not match for example, etc.

 

[Brian McInturff]

Hmm, maybe you are pressing down and removing too much steel. I've not seen any additional steel powder around mine. Actually less because I'm removing less.

 

[robo hippy]

Safety glasses should always be worn with every grinder. With the CBN wheels, you may not need full face protection like you should have with a standard grinding wheel, but it wouldn't hurt. The metal dust can be controlled some what with a plastic bag and a strong magnet, but lots will still fly off. Maybe you can make a guard to go around the wheel to contain the metal dust. I just sweep it off in with the shavings.

robo hippy

 

[Sergio Villa]

Hmm, maybe you are pressing down and removing too much steel. I've not seen any additional steel powder around mine. Actually less because I'm removing less.

I'm very light in my grinding. Proof is that the tool is barely warm after a lot of shaping. In fact I use the CBN only for that (and for scrapers) and then I sharpen with a Tormek. Superior results in my opinion. But the metal particles are there. Probably they bounce back on me because I have the Grinder close to a wall. I may try with a wet rag in the back of the grinder to "absorb" the particles. Still surprised that nobody mentioned this problem, only D-way in his video mentions, only en passant, that one can remove them with a magnet, but he does not use any safety precaution, if I recall well.

 

[JeffSmith]

Sergio: I've been using CBN wheels for a little over a year now, on a slow speed grinder; both 80 and 180 grit with the guards removed. I've got a 'recycled' magnet from an old tool rack - those cheap vinyl magnetic sheets. Cut them up into two pieces each. They fit perfectly over the top of the Wolverine bases under each wheel. I find very little steel shavings around the grinder - what is there is pretty much concentrated behind the grinder.

Just pull off the magnets and wipe over the end of the vacuum hose once in a while.

 

[Bill Boehme]

Sergio, you can only do so much shaping before you will be down to a nub on your tools. How many times in the life of a tool will it be shaped -- once or twice ... maybe three or four times at the outside. While I can appreciate the desire for less grit all over the place, that sure does sound like you're relegating the CBN to rather limited duty.

As already mentioned: ALWAYS WEAR SAFETY GLASSES AND A FACE SHIELD AND RESPIRATORY PROTECTION WHILE TURNING. That includes using the grinder. There is no good reason to remove the safety gear when grinding.

I presume that you already know that regular tool sharpening on a CBN wheel or a Tormek should result in removing only a couple thousandths inch of metal. That is less than the thickness of 20# printer paper.

BTW, I also use a Tormek and agree with you thoughts that it gives a sharper and longer lasting edge. However, I recently tried out a friends CBN wheel to sharpen a Lacer skew and I must say that it is pretty close to the Tormek in edge quality. I can tell the difference, but I would recommend to anybody who has neither to get the CBN unless they have other reasons for needing a Tormek. That was my situation -- I bought my Tormek about fourteen years ago when turning wasn't even on my radar. I wanted it to sharpen jointer and planer cutters as well as hand planes and chisels and other shop tools. I also use it for scissors, knives and nearly anything with an edge.

Regarding sharpening scrapers on the CBN wheel as opposed to the Tormek ... why? The results are far better on the Tormek and the edge lasts longer. Of course, the difference with the Tormek is that you must pull a bur on the scraper in the same manner that you would do it on a cabinet scraper. That adds a few extra seconds to the sharpening task. That type of bur is strong and long lasting as opposed to the weak crumbly bur that one gets from a bench grinder with CBN or aluminum oxide wheels.

I am wondering about the statement that the tool feels barely warm after sharpening with the CBN wheel. I do not have enough experience using the CBN wheel (one tool), but I do not remember that the tool felt any warmer as a result of sharpening. I certainly might be wrong, but maybe someone will clarify that for me.

 

[hockenbery]

As already mentioned: ALWAYS WEAR SAFETY GLASSES AND A FACE SHIELD AND RESPIRATORY PROTECTION WHILE TURNING. That includes using the grinder.

BTW, I also use a Tormek and agree with you thoughts that it gives a sharper and longer lasting edge. However, I recently tried out a friends CBN wheel to sharpen a Lacer skew and I must say that it is pretty close to the Tormek in edge quality. I can tell the difference, but I would recommend to anybody who has neither to get the CBN unless they have other reasons for needing a Tormek. That was my situation -- I bought my Tormek about fourteen years ago when turning wasn't even on my radar. I wanted it to sharpen jointer and planer cutters as well as hand planes and chisels and other shop tools. I also use it for scissors, knives and nearly anything with an edge.

I agree on this. The Tormek has one other advantage in that it is much less intimidating than a high speed or medium speed grinder can be a big plus for some people.
I own a Tormek and like two close friends who own one never use it for turning tools other than a skew between the hundreds of honings.
I would choose an aluminum oxide wheel over the Tormek for gouges and scrapers which gives me a good useable edge on the tools much faster.

The Tormek does put a superior edge. But unless you are turning the lathe by hand it is not noticeable. Mine sits in the corner unless I need to sharpen Planer blades or jointer knives. still the Tormek is the finest sharpening system I have used.

I did not buy a CBN wheel at the AAW in Tampa. I went thinking I would. From my informal survey of vendors those selling CBNs happier than those not selling CBNs. A lot of CBN purchasers did not buy much else.
General consensus I got on CBNs was that they out perform 3X wheels on particle steel tools but aren't noticeably better on M2 steels.
Since I only have 3 Thompson gouges out of 30 odd tools we use I decide against it. Another inch off my 3X wheels and a CBN could replace it.

Al

 

[Sergio Villa]

I use the rest for the Tormek and its jigs on both the Tormek and the Baldor thus I can use the Tormek for edge maintainance once I got the shape I want: it takes no more that ten seconds ans the edge is perfect every time.
Obviously I use the Tormek for plane blades, chisel and everything else that needs a clean sharp edge and when I want a crisp cut. In cabinet making and carving sanding should be the extreme last resort, in my opinion because it takes away the light reflection from the wood.

 

[robo hippy]

Well, I am another person who has a Tormek that is pretty much covered by dust. I only use it to sharpen my kitchen knives (I don't use the jig), and like others, I bought it before I got into woodturning. Maybe some day I will sharpen my planer and jointer blades on it, but will probably get a carbide insert head for both of them. Now, I have sharpened my gouges a couple of times on the Tormek, and could notice no difference in how they cut when compared to the CBN wheels. I never tried a scraper on the Tormek. With the older white Aluminum oxide wheels, the burr you got on a scraper was a wire, and it would melt away very quickly. The burr from the CBN wheels is as sturdy as a burnished burr, and I can tell no advantage between either one, other than I can go straight from the CBN wheel to the wood, but to burnish a burr, I have to hone first. I have burnished straight from the grinder, first on the top surface of the scraper, then on the bevel. I do burnish by hand with a triangle burnisher. It works, but more trouble than it is worth. I rely heavily on scrapers for all of my roughing cuts when turning bowls, and they do excellent peeling cuts on rolling pins.

robo hippy

 

[hockenbery]

A long long time ago I took my gouge sharpened with and Ellsworth Jig on an 8" AO wheel to a Tormek woodworking show booth to ask the rep how to set up their jig to reproduce the grind. We got interrupted and while he was answering the interuptee the rep forgot where the my gouge came from and he began using it to illustrate the superior edge the Tormek would produce.

The rep could not set the jig to reproduce the grind. However Tormek users might check out some add ons Don Geiger has invented. With the Don Geiger add ons you can reproduce the Ellsworth grind on the Tormek!

 

[Bill Boehme]

The rep could not set the jig to reproduce the grind. However Tormek users might check out some add ons Don Geiger has invented. With the Don Geiger add ons you can reproduce the Ellsworth grind on the Tormek!

I figured out many years ago how to do it with the Tormek jig. The information also has been on the Tormek website and in the Tormek book for several years. In addition to all that, you can always use the Ellsworth jig with the Tormek by making a suitable base to hold the end of the pivot arm of the Ellsworth jig. Using the Ellsworth jig works a bit better than the Tormek jig because the support arm on the Tormek slightly limits the amount that the tool can be rolled to the left. For anybody who has the new Johannes Michelsen jig, it can be used with the Tormek to put an Ellsworth grind on a bowl gouge.

 

[Bob Chapman]

I've had a CBN wheel for some months now and find that it gives a much sharper edge that doesn't seem to last anywhere near as long as the edge from the previous wheel. I also find it produces metal dust and started to catch that with a magnet in a plastic bag. That worked fine until I ground some high carbon steel and the big fat sparks ignited the metal on the magnet. I saw it happen so there was no real danger and it was quite interesting to watch the red-hot glow progress from one side of the magnet across to the other. The plastic bag didn't like it much though! Now I just sweep it up.

Bob

 

[Bill Boehme]

I've had a CBN wheel for some months now and find that it gives a much sharper edge that doesn't seem to last anywhere near as long as the edge from the previous wheel. I also find it produces metal dust and started to catch that with a magnet in a plastic bag. That worked fine until I ground some high carbon steel and the big fat sparks ignited the metal on the magnet. I saw it happen so there was no real danger and it was quite interesting to watch the red-hot glow progress from one side of the magnet across to the other. The plastic bag didn't like it much though! Now I just sweep it up.

Bob

Well, next time you'll know to use a paper bag instead.

Have you observed anything that might explain the cause of this seemingly counterintuitive behavior of edge longevity?

I use a Tormek which gives a sharper edge than either the CBN or the composite grinding wheels. I have never done a "real" comparison of usable edge longevity, but my gut feeling is that I get a bit more use from an edge sharpened on the Tormek compared to the others. Also, I feel like I get better results when shear scraping with the Tormek sharpened edge.

Alan Lacer published the results of tests that he did a few years ago comparing different sharpening methods and performance results complete with photomicrographs. The results were no real surprise since they supported common intuition that smoother more refined edges were more durable than ragged edges.

Things like edge longevity are not easily quantifiable because there will always be so many uncontrollable variables. Besides that, personal preference trumps everything else. Those who have been turning for about a decade might remember the late Jim King in Peru. There were pictures on his website showing some of the "turning tools" used by his employees. My favorite was the Volvo leaf spring scraper sharpened on a belt sander. They got amazing results with their improvised tools and methods of sharpening.


"Sharper" as I used it here means that the cutting edge is less serrated.

 

[n7bsn]

missing Jim...

.... Those who have been turning for about a decade might remember the late Jim King in Peru. ......

I was selling at a Holiday show today, and some people were remarking on some of the amazing woods in a couple of my things, they were woods I got from Jim, and apparently he was the only person selling those woods....

Jim is one of those sorely missed people.

 

[Bill Boehme]

I was selling at a Holiday show today, and some people were remarking on some of the amazing woods in a couple of my things, they were woods I got from Jim, and apparently he was the only person selling those woods....

Jim is one of those sorely missed people.

I still have one or two pieces of his wood.

He had found some species that he was sure hadn't yet been "discovered" and classified by botanists.

 

[robo hippy]

Bill,
I have tried a Tormek sharpened gouge only a few times. I could not tell any cutting difference or durability difference in the edges that I get from my CBN wheels. I have had CBN wheels for 8 to 10 years, and can't remember what the edge from a standard grinding wheel is like.

robo hippy

 

[Bill Boehme]

If there is a difference, it probably isn't worth mentioning. I have only sharpened a skew on a friend's CBN wheel and I was duly impressed.

 

[Johnnie Johnson]

Hello, I recently mounted a eight inch 80 grit CBN wheel on my seven inch Baldor. Of course I had to remove the protective screen and guards. The result is not so satisfactory. It is true that it grinds true and faster and without dust, but the metal particles are everywhere. I now have to use protective glasses after risking some iron particles in my eyes.
The surprising thing is that nobody that I know mentions this problem which could be a safety issue besides a messy problem. Metal particles and ball bearings do not match for example, etc.

Sergio, question about your Cbn setup: how did you mount an 8” wheel on a 7” Baldor Grinder? Doesn’t that entail removing the inner portion of the guard which exposes the bearing?
Johnnie Johnson

 

[Glenn Lefley]

Sergio, question about your Cbn setup: how did you mount an 8” wheel on a 7” Baldor Grinder? Doesn’t that entail removing the inner portion of the guard which exposes the bearing?
Johnnie Johnson

Yes and I think that is his problem the wrong size wheel,on his grinder and the metal particles are going to ruin the bearings in his expensive grinder.

the easy solution is they do sell 7 inch cbn wheels for baldor grinders. I think they are around $150.00.

 

[Dean Center]

One other thought on the original question. Sharpening with the same technique and steel removal on a stone wheel and a CBN wheel should produce EXACTLY the same amount of metal debris, shouldn't it?

The difference is that with the CBN there is no fractured stone powder produced. Perhaps what you're seeing as a difference is the lack of the stone dust. Perhaps the stone dust obscured or changed the flight path of the metal dust before you went to CBN. In any case, the bad pooky available to breathe into your lungs is now less than before.

 

[Lars Hansen]

As Dean points out: If you are able to sharpen your tools on a alox wheel removing just as little material as with a CBN wheel (I can't), of course you get the same amount of metal particles and with alox, it will be mixed with stone powder.
The dust may be finer with CBN due to higher grit numbers used.
Since this seven year old thread was started, many more of us use tools with a far higher percentage of other "ingredients" like cobalt, tungsten etc. One more reason to use a mask.

 

[Tim Tucker]

Magnets, magnets...and more magnets. They are cheap and easy ways to capture much of the metal shavings. Respiratory and eye protection should be considered absolutes. And...from what we now know - a 180 grit CBN is the most often suggested for the "rough" wheel, and a 600 grit for the fine.

 

[robo hippy]

Just found this. Not made for the home shop, but a start....

View: https://www.youtube.com/watch?v=3kZ4haT2F3U&feature=youtu.be


robo hippy

 

[Tim Tucker]

Reed - THAT is a great idea...and does not look like it would be hard to make. I think of a shop vac - with a Goretex type filter to capture fine dust...and a good sized strong magnet in the vac - to collect most of the metal dust.....Thanks for posting this.

 

[john lucas]

I rigged up a dust collector on my grinder before I got the CBN wheels. I was too nervous about sparks possibly causing a fire so removed it. I may have to rig up another one. I just used a small Shop Vac and connected a Y set of hoses to it.

 

[Mark Jundanian]

https://www.woodturner.org/common/Uploaded files/AmericanWoodturner/AW2010s/AW3404-2019.pdf

On page 16 of AWT August 2019 there is a tip from Mitch Friedman showing how to set up a dedicated shop vac with PVC pipe for the purpose of collecting grinder dust. I've had one on my grinder with CBN wheels since last August. It works very well, not perfect, but better than the magnets I had using previously.

 

[Mark Jundanian]

I rigged up a dust collector on my grinder before I got the CBN wheels. I was too nervous about sparks possibly causing a fire so removed it. I may have to rig up another one. I just used a small Shop Vac and connected a Y set of hoses to it.

I was posting at the same time as your message. One of the points that AAW made in publishing the above tip is that the vac must be dedicated to collecting the grinder dust. There must not be any wood dust. So the vacuum I used was first thoroughly cleaned and is not used for any other purpose. AAW also makes a point that the PVC tube should be grounded to prevent static shocks. I confess I have not done this. I have a total of about 3 feet of 1 1/2" PVC in the system and thus far have not been shocked. I also use this for a grinder with CBN wheels and that I only use on HSS tools, so sparks are already at a minimum.

 

[Doug Rasmussen]

Hello, I recently mounted a eight inch 80 grit CBN wheel on my seven inch Baldor. Of course I had to remove the protective screen and guards. The result is not so satisfactory. .................................................................................

Removing the guards was your first mistake. I realize the AAW (at least this part of the AAW) seems to condone the practice. It's still a really bad idea.

 

[Steve Tiedman]

Removing the guards was your first mistake. I realize the AAW (at least this part of the AAW) seems to condone the practice. It's still a really bad idea.

Imagine the multiple parties to that lawsuit in the worst case scenario.

Please reconsider using the improper size wheels for the grinder and the need to operate said wheels without the proper machine guards in place.

Steve.

 

[john lucas]

With a CBN wheel there isn't anything to explode so I don't see a problem with removing guards. I have removed the outside guards on mine because the wheels were too thick.

 

[Donovan Bailey]

Sergio:
I have a more basic issue that you can resolve...are those walnut shavings that are stuck to your dog? Mercy! If not, would you mind telling me what kind of dog that is? Thanks...

 

[robo hippy]

Well, I have been sending some e mails to them about making a more affordable variation. They didn't seem interested, mostly because of what the cheap imports would do to it if they did develop a bench top model. A valid point. I had mentioned the same idea to Oneida about metal dust collection and they said some thing like 'we will have to think about it. So, where does that leave us? Not really sure.

First, I would never operate a grinder without at least half of the wheel guard on. Sure, there is no risk of the CBN wheels blowing up, but for me, it is a matter of dust containment. The metal particles that come off of the CBN wheels will float around in our shops like the dust particles do, hanging in the air for days. No, it doesn't sink out of the air because it is heavier than wood. You do not want to hook up your wood dust collector to anything that generates any kind of spark at all, small spark with a lot of wind = fire. I would think that the air scrubbers that most of us have in our shops would work fine for amount of air flow, so that they would pull the metal dust out of the air at the source so we don't inhale it. Some of these more modern metals are toxic. The problem seems to be in the filters. Midaco has 2 filters in their dust collector. I didn't get the specs on them, but I would figure that one is supposed to catch all the metal particles and is fire proof, and then the second one catches all the smaller particles. The guy I chatted with did not have specs for motor size or volume of air flow.

Best way to keep dust out of the air is to trap it at the source. This would require us to figure out a way to have a full guard on the wide CBN wheels. I did see some one who had rigged up a spacer so they could do a full guard on the wider wheels. Not sure if that would be some thing that could be manufactured or if we would have to make them ourselves. Having some thing like the barrel I made for when I am sanding my bowls would be nice. With the piece totally enclosed, you capture all the dust, not just some of it. Magnets do work to a degree, but I would guess that at best, they might capture 75% of the dust.

I did suggest to the Midaco people that maybe they and Oneida should get together. Collecting metal dust at the source is a safety issue that, thus far, we woodturners have not addressed. I would believe that collecting all the dust from when the standard wheels are dressed is also a safety issue.

I am not sure about grounding plastic pipe. It seems, if I remember correctly, that even though saw dust flowing through plastic pipe does generate static, it has never been known to start a fire. I have gotten some good shocks from catching my daughter, when she was young, coming down those plastic slides.

robo hippy

 

[Tim Tucker]

I really like the idea of being able to collect the grinder generated metal dust/particles via some form of "hood" or shield. Any additional pictures, or plans that could be referred to or posted would be great to see!
T

 

[Bill Boehme]

Sergio, question about your Cbn setup: how did you mount an 8” wheel on a 7” Baldor Grinder? Doesn’t that entail removing the inner portion of the guard which exposes the bearing?
Johnnie Johnson

Sergio:
I have a more basic issue that you can resolve...are those walnut shavings that are stuck to your dog? Mercy! If not, would you mind telling me what kind of dog that is? Thanks...

Are these rhetorical questions? This is a seven-year-old thread and it has been more than three years since Sergio last logged into the forum.

Johnnie, removing the shroud on a grinder won't expose the bearing, but it does increase metal dust scattering.

Donovan, I'm not sure that's a dog, it looks more like a swamp creature.

 

[Tom Gall]

I was posting at the same time as your message. One of the points that AAW made in publishing the above tip is that the vac must be dedicated to collecting the grinder dust. There must not be any wood dust. So the vacuum I used was first thoroughly cleaned and is not used for any other purpose. AAW also makes a point that the PVC tube should be grounded to prevent static shocks. I confess I have not done this. I have a total of about 3 feet of 1 1/2" PVC in the system and thus far have not been shocked. I also use this for a grinder with CBN wheels and that I only use on HSS tools, so sparks are already at a minimum.

Here's some more on the topic from a few months ago.
https://www.aawforum.org/community/index.php?threads/cbn-grit.16531/#post-167930

 

[Lars Hansen]

I'm in no position to judge if there is a final truth to the PVC static issue, but this appears quite trustworthy:
https://www.woodcentral.com/articles/shop/articles_221.shtml
While waiting for *the* product for avoiding sparks flying down the dust extraction, wouldn't a simple filter do the trick by making the spark burn out completely before meeting anything, it might ignite?
I only see sparks flying from my CBN wheel if I skip brushing gunk from the gouge before sharpening, and I do that anyway to avoid tree sap ect. on my wheels - two times two seconds on a 4" soft steel brush.
Yet, I have a cheap vacuum cleaner turning on and off with the bench grinder and never use it for other types of dust.

 

[Steve Tiedman]

@Lars Hansen, I, too, have a dedicated shop vac for my grinder. A one-gallon Shop Vac brand, and I have its (relatively short) hose plugged onto another hose as an extension. I took the hard pipe end off the second hose, formed a small piece of pvc pipe to the hose with tape to create a 90 degree bend a few inches from the end of the hose, taped scrap foam weather stripping at the very end to act as a jam fitting for the grinder's oval dust chute outlet, and I shove it into the grinder dust chute of the wheel I'm using. It's not perfect, but sparks and grit now travel through a winding 7-8 feet of corrugated tube in a high velocity air stream, likely cooling to under any sort of ignition temp before they hit the paper sleeve filter of the dedicated Shop Vac. I replaced the filter a couple years ago. The old one was dirty gray, there was some grit laying in the bottom of the vac canister, and there were no burn marks anywhere on the filter or vac interior. (Looks like it's time to re-tape that hose end.) I don't use it as much with routine touch-up sharpening, but for heavier grinding and wheel dressing, I turn on the vac.

Steve.

 

[Mark Jundanian]

I'm in no position to judge if there is a final truth to the PVC static issue, but this appears quite trustworthy:
https://www.woodcentral.com/articles/shop/articles_221.shtml

Great article. I'm working my way through it now. Thanks for sharing it.

 

[Lars Hansen]

@ Steve: A maze instead of a filter. One more idea to work with, thanks for sharing.

 

[Philip Greenwood]

I have used one for a few years now. Safty glass of a face shield is always used. I find less dust now then before with the aluminium oxide wheels. Metal still came off with theses aluminium wheels as well but was not as visible when mix with the dust from the oxide wheel.