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Grinding dust

P

Paul Durden

Joined
Feb 2, 2025
Messages
18
Likes
7
Location
Panama City, FL USA
Tool Grinding dust. Is this still a real health concern if I just wear a n90 mask when grinding/sharpening lathe tools? Black dust still gets all over the workbench and nearby. I’m using a Sorby ProEdge. (linisher -belt sander type sharpener)
 
To date, no one makes a metal dust collector for the home shop. Wearing a mask, especially with some of the more exotic metals we are using makes sense. The metal dust can and does float around the shop like wood dust does. Many will use magnets in plastic bags to get most of it.

robo hippy
 
If you darken the room and use a strong, narrow beam light (flashlight), you can watch the extremely fine steel dust particles float in the air. They will hang in the air for a long time and float all around the room. I have magnets on the back of my bandsaw, 10’, facing away from the CBN wheels, and they are all covered with the fine dust. Strong magnets below the grinder will catch some but not nearly all. (The plastic bags will make it easier to clean the dust off the magnet.) Based on what I observed in my shop, I think it would take a pretty big (and impractical) array of magnets around the grinders to catch most of the dust!

Unless some researcher finds that breathing the extremely fine particles adds iron to your blood and is good for you (unlikely!), a good P95, or better, an industrial respirator with P100 filters, is probably the best defense. A ceiling-mounted air cleaner like the Jet might help.

Warning, Danger, Will Robinson: I’ve mentioned this before, but fine steel dust on a magnet near the grinder can also be a fire hazard. My strong magnet below one CBN wheel picked up a big fuzzy ball of steel particles. While a fine CBN wheel creates very few and nearly unnoticeable sparks, they can still ignite the steel. (Fine steel dust and steel wool will burn nicely.) While grinding one day I looked down and saw an orange glow deep in the center of a glob of dust on the magnet. A spark had ignited the steel dust and was forming a orange ball of molten steel in the center. I quickly snatched up the magnet and took it outside. Could have burned down the shop. I learned from that to clear the dust from the magnet often.

JKJ
 
robo hippy said:
To date, no one makes a metal dust collector for the home shop
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I have a JET JDCS-505 metal dust collector stand, which I picked up on a refurb deal. Having measured with my Dylos after some moderately extended grinding, it's 100% clear that it's not even close to adequate to control fine dust. For the record, those tests were with a Baldor 8" grinder, its stock guards and their collection outlets, and a Stuart Batty grinding platform (i.e. very close set around a CBN wheel).

The real problems become evident as soon as you put the problem in light of Bill Pentz' extensive writing on fine dust collection. No bench grinder setup I've seen is remotely suited towards capturing the particles coming off the wheel. Even if the CFM of the JET unit is theoretically adequate, the guard would need to be completely redesigned to have any hope of being effective. Likewise, grinding platforms themselves almost couldn't be better at diverting metal particles away from existing guards and any collector attached to them.

I think it's possible to do a lot better, but I haven't tried yet(**). The first problem is to completely redesign the guards so that they have any hope of intercepting nearly all of the fine dust ejected from the wheel. The stock guards are really designed to handle a friable grinding wheel failure and explosion, not to capture a meaningful amount of dust. The second problem is to ensure that dust intercepted by a platform can also be captured and directed into the collector. I have a suspicion that a really decent system will be a combination of a physical guard design and some carefully placed strong neodymium magnets to act as "metal dust guide fields", to get more dust into the collector rather than just grabbing some free-floating metal dust out of the air. If you're just grabbing free floating metal dust, the game's already lost.

Related, I won't believe any metal dust capture system is effective if there are no reliable air quality measurements included.

(**) I'm always using PPE at the lathe anyhow, formerly a North system P100 half mask, now a Sundstrom PAPR. I vent the entire shop's air with the big extractor fan in the back before doffing that gear.
 
John Whitley said:
I think it's possible to do a lot better, but I haven't tried yet(**). The first problem is to completely redesign the guards so that they have any hope of intercepting nearly all of the fine dust ejected from the wheel.
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Or put the grinder in an industry standard glove box. These are widely used where various hazards must be contained. A resourceful person could make one.

Industrial gloveboxes can cost $1000s but those made for mushroom people might work if tools are removed from the handles.

Be far better to design one specifically for sharpening, though.
 
I've been toying with the idea of making downdraft table, enclosing the grinder as much as reasonable, getting a cheap harbor freight dust collector, and venting it outside. Even in winter it would just be short bursts that shouldn't kill the heating too bad.

I just need to find a large enough shut off value or damper for the outside vent. Better would be a two way so I could also vent wood dust outside during warmer weather.
 
Brian LaRochelle said:
I've been toying with the idea of making downdraft table, enclosing the grinder as much as reasonable, getting a cheap harbor freight dust collector, and venting it outside. Even in winter it would just be short bursts that shouldn't kill the heating too bad.

I just need to find a large enough shut off value or damper for the outside vent. Better would be a two way so I could also vent wood dust outside during warmer weather.
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A good friend of mine mounted a 3’ fan in the wall behind his lathe and blows all the dust outside through some louvers. He only turns when the weather is warm enough! Has to hold onto small pieces of sandpaper. :)

Same thing might work for sharpening dust.

JKJ
 
I have thought about making a hood similar to my sanding hood which may work. I have also thought about one of the air scrubbers and making a small box/hood for it as well. Both could work. I did look at that Jet product, and $1500 is a bit much for a home shop, though if you can find a rebuilt/refurbished one that would help. I did talk to Oneida about making one and they thought it might be a good idea. I would think we would need a fire proof filter, and low to medium air flow. Not nearly what we need for dust collection. Not enough interest from the manufacturers, though I think they would sell well.

robo hippy
 
Along with @robo hippy's hood idea, I'm suddenly thinking about my dust collector hood behind my lathe.
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Build a box that completely surrounds the 5 sides of the grinder and have one big source of suction at the rear of the box pulling a ton of air. Far more than my 650cfm 2-bag collector.

I'm picturing something like 1500-2000cfm squirrel cage furnace fan with its inlet fed by a large diameter steel duct ran to the rear of the box, and a 4" pleated filter at the inlet of the duct.

Or rig up a Jet whole-shop air filter ($800) at the rear of the surround box, with another sacrificial pleated filter at its intake to grab a majority of the metal particles. Jet claims 1700cfm on high (probably free flowing cfm- no filters at the inlet).
 
Something to think about for sure. I actually have the powermatic version of the filtration system you referenced above the grinder. Haven't thought about running it while grinding until I saw a previous comment about fine airborne metal particles. Hopefully it will help with that. They are adamant however, about not using for anything besides airborne wood dust. Oh well...we will have to see. It's easily 7 feet above the grinder, ceiling mounted, so I don't see how any sparks could get that high. Thanks for the idea
 
Being in the phase of my wood-turning journey in which I am learning to grind the way I actually cut and use tools, I tend to do a lot of grinding these days, especially on my 80-grit CBN (and especially with my less expensive Sorby, Hurricane and BB tools, which I don't resent experimenting with so much). One thing I have started doing when I am generating a lot of heat on one tool and I want to keep going is to spray the wheel with water as I also dip the tool frequently. This cools things down and also makes at least some of the grinding dust collect more into a mud slurry around the platform. And like John wrote about above, I have also looked down to see the scary glowing dust coal around my plastic-bagged magnets, ready to burst into flames at any second, another reason I am spraying with water periodically. Okay, won't this make your wheel rust, you might ask? Just a tiny amount on the sides of the wheel is all I see so far, so I'm going to keep doing it for the time being. I have also been spraying water when setting angles on my skews with a 60-grit belt on my 2x72" belt grinder with a platen before establishing the concave bevel on the wheel with good results

If I'm not wiped out after a long grinding and turning session, I'll take that day's used shop towels, spray them with water and wipe down thoroughly all over my grinder, jigs, base, etc., trying to get up more of the black dust before I use a shop vac or compressed air on it. And lastly, I finally broke down and ordered the PEKE PowerCap Bundle, which is supposed to be here Tuesday. I'm really stoked to start using a real mask that incorporates at least some eye/impact protection.

None of our dust-mitigation solutions are a magic bullet, but taken together, every little step helps, I think.
 
I would not want any high speed/volume collector for metal dust, even with the CBN wheels which do put off some sparks. The risk of fire is too high. A smaller room fan and a fine particle dust filter may work well. I still would want it far enough away from the grinder that any sparks would be dead by the time they got to the filter. A hood cover on 5 sides like Steve's box up above could work, but you need to make sure that the end covers don't restrict your tool handles when you sharpen....

robo hippy
 
Mark Jundanian said:
Apropos of Aaron's comments, airborn dust control is an inherent feature of a wet wheel system, like Tormek. Of course one then has to dispose of the slurry in the water trough. (Pouring it down the drain is not necessarily a good idea).
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You are so right - I completely forgot about that. I have two Tormeks and the water collected all the metal particles when I used the original water wheels. However, when I switched to CBN wheels, Rizza said not to use them embedded in water for an extended or the wheel could be damaged by corrosion.

Not a big problem, since now I only use 1200 grit on the 10” wheel, the slow speed and the 5 seconds it takes to sharpen my spindle gouges puts no detectible steel dust in the air - checked with magnets and the bright-light beam technique. (I do wet the wheel with a squirt of good diamond honing compound.) In contrast, my coarse 60 grit wheel on a 1/2-speed bench grinder throws a LOT of fine steel dust!

And hey, I found a good use for the fine steel dust collected from the coarse wheel - I save it for friend, science/tech/experimenter/inventor. He experiments and makes all kinds of things. (The dust might be a good additive to caulk or adhesives - maybe an JB Weld substitute.)

BTW, note that some people have expressed concern that using a dust collection system to suck up steel dust from a grinder might be a fire hazard if a spark found it’s way to dust somewhere in the duct. Since the sparks from CBN are small with short trails t seems unlikely but worth considering. At one time I found references to dust collectors used in industry that had spark guard filters.

JKJ
 
John K Jordan said:
BTW, note that some people have expressed concern that using a dust collection system to suck up steel dust from a grinder might be a fire hazard if a spark found it’s way to dust somewhere in the duct.
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Dust shouldn't be hanging around in your ducts or you have a real problem with your dust collection system design – the line speeds aren't high enough. At that point, your chip collection is marginal and probably nothing good can be said about it actually capturing fine dust.

Still, the risk as I've heard it, and as a friend who runs a production cabinet shop experienced first hand (they got through, barely) is that a spark gets into the collection bins where it slowly, quietly smolders and only many hours later may develop into smoke and actual fire. For flat woodworking, one scenario is metal-to-metal contact of some sort. Either machine tooling hits metal in a workpiece, or something goes seriously awry and the machine contacts itself. For example, my poor old sliding table saw had an "impossible" notch cut in the blade-side slider edge when I got it. The only thing I can figure is that a workpiece was torqued clockwise during a cut, causing the blade to destruct – but that's a wild guess and barely makes sense given how a slider is used. There's a similar risk of an ember getting deep into a CNC router's MDF spoilboard and catching fire much later, but as I understand that's usually from some combination of feeds, speeds, and/or poor tool condition that really burn the workpiece.

If a main shop dust collector, used for wood chips and dust, is used for a grinder collection system then I think it should be setup to completely isolate sparks and metal dust from the main system. I note that Grizzly has dedicated metal dust collectors, but those also definitely are overkill-priced (and often sized) for a typical home turning shop.

Ultimately, I think for most turners (myself included!) this comes down to: wear a good quality and well-fitted mask/respirator when turning and grinding, and have a plan for cleaning up the shop air when you're done. I've gotten very mixed messages regarding whole-shop air filters, such as the ceiling mounted units. At least some of them have been reviewed to basically just push the dust around... but I suspect at least some modern solutions have stepped up and improved their designs?
 
Brian Gustin said:
LOL there's been days I've been tempted to do the same...
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Same here-It occurs to me more and more that turning wood , in addition to being enormously messy, expensive and potentially dangerous in so many ways, also requires the learning of literally dozens of separate skills more or less all at once. I was chatting with a fellow turner on Instagram about this. And some days in the shop, nothing goes right, and you wish you had never opened your shop door that morning. And then another day you finish a piece that turns out even nicer than you had hoped, and you're back in it deeper than ever. It's a sickness, I tell ya!
 
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