metal dust

[Dave Fritz]

Other than magnets what do you do to limit the metal dust in the air from a CBN wheel?

[Reed Gray]

Some thing I have been pondering for a while. I am thinking of a hood and a low volume air scrubber far enough away that any spark will be gone by the time it gets to the fan and filter. Magnets get some of the dust. High volume like my shop DC would be a high risk of fire. Other than that, grinder by the window, in a hood, and fan at the back of the hood to suck it all out. Fine in summer. That fine dust does hang in the air for a long time, just like wood dust, and some of the exotic metals can be toxic.

robo hippy

[JohnC Lucas]

I haven't really worried about it much. I have a magnet on the outside of my dust shroud. The rest just seems to collect on the bottom of the grinder. I sharpen near a window and really don't see a dust cloud. My older Aluminum oxide wheel produces a noticeable dust cloud so I turn the dust collector on and move the hose nearby. I have 40 feet of metal pipe before it gets to the dust bag and I really don't see sparks coming from the CBN wheels so I haven't worried about that either.

[Reed Gray]

One turner, I can't remember who, hung a magnet 10 feet away from his grinder and it picked up dust.I found some inside a cardboard box that was 2 feet above my grinder, and had the dog eared type of flaps that tucked into the sides of the box. There was a magnetic base inside the box. Some of the fancy metals have materials in them that are toxic and in industrial situations, filter type masks are mandatory. So, maybe I am a worry wart about this, but I don't think it should be ignored.

robo hippy

[Greg Parrish]

One turner, I can't remember who, hung a magnet 10 feet away from his grinder and it picked up dust.I found some inside a cardboard box that was 2 feet above my grinder, and had the dog eared type of flaps that tucked into the sides of the box. There was a magnetic base inside the box. Some of the fancy metals have materials in them that are toxic and in industrial situations, filter type masks are mandatory. So, maybe I am a worry wart about this, but I don't think it should be ignored.

robo hippy

Think that was John K Jordan.

[John K Jordan]

Think that was John K Jordan.

Yes, that was me. I had strong magnets stuck to the back of my bandsaw that I found covered with fine steel dust. I turned out all the lights in the shop except for one bright beam and saw steel dust floating in the air after reshaping shapers. I use some magnets under the wheels but they don't catch it all. How long will the fine dust float in the air? When is it safe to remove the respirator? Should I move the sharpening outside or into another room? I plan to add a hood connected to the DC "someday."

I have no idea what fine steel dust does to the lungs over time. Does it accumulate over time, is it harmless, will the body carry away and use the oxidized iron and accumulate toxic components? Are trace amounts of things like chromium and vanadium toxic? I hope the medical future doesn't look back on these years as the time before the serious long-term hazard of sharpening with CBN was discovered and all the CBN makers went bankrupt from lawsuits. (Perhaps identical fine dust has always come from grinding and no turners noticed. Time for some googling.)

JKJ

[Eugene Dixon]

I've had a few MRIs over the last 18 months. They all seem to have benefited the medical practitioners/insurance companies more than me. Nevertheless, before taking the 'nap', the technicians always ask about how much metal grinding I've done. So far, it hasn't been an issue.

To Reed's point about hoods, I'm thinking that gloveboxes will be a staple in all of our shops in the future. Not only for grinding stations but also for sanding stations, lathes, etc. Maybe.

The next generation of dust control will be gloveboxes with airlocks. Maybe.

OBTW, with Flanders and Camfil Farr nearby, I should start a woodworkers glovebox retail outlet, LOL. Maybe.

[Bill Berklich]

Any time I dry grind I do it with the garage doors and windows open and a mask or I run a pair of Honeywell 50250 True HEPA Filters that pull down to 0.3 microns. I don't run them when I'm cutting wood because the filters fill up fast. I try to do the bulk of sanding outside. The HEPAs cost about $300 ($50/filter) a year to operate for filter replacement. Needed? maybe. Worth it? It must be because I'm still doing it. Effective? Won't know until they autopsy my lungs :-)

BTW, I've been using JK's strong magnet idea just to check up. So I have 3 exotic magnets in three locations at chest height. No accumulation of material on them over the past 6 months.

Post Script - I stand somewhat corrected. I don't have the same metal dust problem as some on this post as I don't run CBN wheels.

[JohnC Lucas]

I keep all my magnets stuck on the side of a tool box about 7 feet from the grinder. There isn't any metal dust at all on those magnets. Actually now that I think about it there are 4 that I use to fasten my photo paper to my table saw that are closer, probably 6 feet or less. No metal on those. I try to think about dust control and run my collector a lot but simply don't panic over it. It's kind of like everything that California considers hazardous the rest of us just sort of take with a grain of salt. It's always good to know about the dangers and then take the precautions you feel good about. I just don't go overboard. I've been working in wood for 40 years or more and the early years were with no dust collection of any sort and I'm still around. In my first shop sometimes there was so much dust it was like a fog. Yea I know now that it was bad but I simply had to work with wood and did the best I could in the locations I had.

[John K Jordan]

The only magnets I noticed the dust on are extremely strong super magnets, about 1/2" cubes, so strong I have trouble removing them from the steel bandsaw surface. They are on the back side of the bandsaw near the wall, about 6 or 7 ft above the floor. They were there for a year or more before I noticed the metal dust. The dust accumulate was light but definite. Some reasons for what I found might have been time, height, placement in the natural air circulation path, or extended heavy grinding, major reshaping multiple thick scrapers on an 80 grit wheel. Perhaps steel dust accumulation from normal sharpening would be more difficult to detect.

I think I'll try a test: fasten some pieces of white paper to the magnets with thin double-sided tape and stick several around the shop, one on the ceiling above the grinders and several on the walls about head height, maybe one lower. That ought to make any black dust show up easily.

I also want to look at some of the existing particles under the microscope. Just with the eye they look much finer than the mass of particles that stick to the magnets just below the grinders.

I want to make some more magnet collectors for the grinders too. I may try the method on one of the magnetic job-site sweeps I have - pull a handle to release any nails picked up. I'm thinking some cylindrical magnets inside plastic tubes with a means to pull away and release the dust. (That fine steel dust would be perfect for making thermite!)

I keep all my magnets stuck on the side of a tool box about 7 feet from the grinder. There isn't any metal dust at all on those magnets. Actually now that I think about it there are 4 that I use to fasten my photo paper to my table saw that are closer, probably 6 feet or less. No metal on those. I try to think about dust control and run my collector a lot but simply don't panic over it. It's kind of like everything that California considers hazardous the rest of us just sort of take with a grain of salt. It's always good to know about the dangers and then take the precautions you feel good about. I just don't go overboard. I've been working in wood for 40 years or more and the early years were with no dust collection of any sort and I'm still around. In my first shop sometimes there was so much dust it was like a fog. Yea I know now that it was bad but I simply had to work with wood and did the best I could in the locations I had.

[Dave Bunge]

I think I'll try a test: fasten some pieces of white paper to the magnets with thin double-sided tape and stick several around the shop, one on the ceiling above the grinders and several on the walls about head height, maybe one lower. That ought to make any black dust show up easily.

John, that sounds like an interesting test. Do you have one of the Dylos air quality meters (laser particle count meters)? I seem to remember that you do from some previous posts. If so, perhaps you could use it. Have someone hold it in your breathing zone, near your nose, while you grind and see if the particle count increases. Maybe repeat, holding the meter behind the grinder or where ever you think the grinding dust would travel.

Gravity is the only thing I use to collect metal dust when I sharpen. At the end of the day, I use my dust collector hose to pick up the dust under and behind the grinding wheel. I've been leary to use my dust collector while grinding due to sparks and haven't gotten around to installing magnets to help catch the particles. I do wear a half face respirator with P100 cartridges whenever I'm sharpening, and most of the time while I'm in my shop.

I have one of the Dylos air quality monitors that I keep on my bench, about 8 feet from the grinder. I don't notice any increase in particle count when I sharpen (180 grit CBN wheel). When I still used an aluminum oxide wheel, I would see a huge spike in the particle count when I dressed the wheel. I started holding my dust collector hose near the wheel when I was dressing it and that helped a lot.

I'd be very interested to hear if results are affected by the grit of the grinding wheel. It seems like finer grit wheels would make smaller particles. Smaller particles settle out of air more slowly (look up Stokes law: terminal velocity is proportional to the square of the diameter, so particles half as large take 4 times longer to settle). So if you only use gravity to collect the particles, you might be breathing more dust with a finer grit wheel. But on the other hand, smaller particles should be easier to collect with a vacuum hose if you figure out how to hook one of them up safely. I don't have a clue how particle size would affect the ability of magnets around the grinding wheel to capture dust.

Dave

[Adam Wager]

With some of the more exotic powdered metals, does anybody know whether the dust remains a composite of the various components or are the particles small enough that some of the non-ferrous (and non-magnetic) ingredients will be isolated in the air and avoid attempts at magnetic capture?

[Mike Nathal]

Yes, the dust "remains a composite of the various components" and can be captured magnetically.

Also, I added a small strong magnet INSIDE the dust shroud, on the bottom of the shroud. It is ~ 1 X 0.25 X 0.060" --- it collects a lot of metal filings. Since inserting it, I have noticed the general debris (black iron dust) in front of the grinder has been reduced by a quite a bit, maybe 90%

[Dave Fritz]

Mike, that's really interesting. Would you mind posting a picture of your grinding station?

Yes, the dust "remains a composite of the various components" and can be captured magnetically.

Also, I added a small strong magnet INSIDE the dust shroud, on the bottom of the shroud. It is ~ 1 X 0.25 X 0.060" --- it collects a lot of metal filings. Since inserting it, I have noticed the general debris (black iron dust) in front of the grinder has been reduced by a quite a bit, maybe 90%