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Thread: Controlling dust from CBN wheel grinding

  1. #1
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    Controlling dust from CBN wheel grinding

    I finally setup my grinder with a CBN wheel. CBN wheel is larger and the original wheel guard no longer fits. I see a lot of pictures of people using them without guards. So, that is what I have been doing. However, there is quite a bit of metal dust coming out. I don't want to use my DC as I worry about sparks causing fire hazard. What are effective options to capture dust from grinding tool steel (plane blades, chisels, etc)?

  2. #2
    I lay some damp/wet paper towels under the wheel and clamp one edge to the grinding rest, it captures quite a bit of the dust.

  3. #3
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    Solder fume extractor?

  4. #4
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    Quote Originally Posted by Frank Martin View Post
    I finally setup my grinder with a CBN wheel. CBN wheel is larger and the original wheel guard no longer fits. I see a lot of pictures of people using them without guards. So, that is what I have been doing. However, there is quite a bit of metal dust coming out. I don't want to use my DC as I worry about sparks causing fire hazard. What are effective options to capture dust from grinding tool steel (plane blades, chisels, etc)?
    You could use a spark inhibitor screen on your DC. I did a google search once and found a variety of industrial solutions. Industry has been dealing with this for a long time.

    The steel dust from CBN is terrible. In the right light you can see the steel floating in the air like talcum powder. I've found a buildup on magnets on the back side of my bandsaw over 10' away. Best to wear a good mask and use an air cleaner like the Jet.

    Some people put strong magnets under and behind the CBN wheel which picks up an astonishing amount of steel dust in short order. Some put the magnets in plastic bags so they can dump the dust more easily. One warning, remove the feathery gob of dust regularly. I didn't and in spite of noticing only occasional and very small sparks, the hairy ball on the magnet caught fire one day. No flame, but I saw a glowing mass of molten steel down inside the fluff ball. I took it outside before it burned a hole in the table.

    JKJ

  5. #5
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    I'm anxiously awaiting the next version that Tormek comes out with, because I won't use the CBN grinder in the old houses I work on. If I needed one now, I'd buy the T8, but am hoping they come out with another model. It will be probably next Summer before I really need one.

    What I'd really like to have is one that uses two of their diamond wheels, and has reverse.

  6. #6
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    Quote Originally Posted by Tom M King View Post
    I'm anxiously awaiting the next version that Tormek comes out with, because I won't use the CBN grinder in the old houses I work on. If I needed one now, I'd buy the T8, but am hoping they come out with another model. It will be probably next Summer before I really need one.

    What I'd really like to have is one that uses two of their diamond wheels, and has reverse.
    I have two Tormeks with 10" CBN wheels, one 1200 and one 600 currently loaned to a friend. I think diamond would be good. I would REALLY like reverse and (continue to) look into converting mine. I want the grinding wheel to run in reverse of normal, and the honing wheels to run in the normal direction. I refuse to turn the machine around as they intend due to the geometry.

    Hey, I suspect a handy guy like you could build his own bench grinder with two wheels that runs at very slow speed and reverses, using a 3-phase motor and a VFD.

    But the higher speed is almost needed for certain operations, such as seriously reshaping heavy HSS tools for woodturning. For that I've used an 80 grit CBN wheel and recently switched to a 60 grit CBN. Even then, the process is quite time consuming. I probably wouldn't live long enough to do it on a slow speed wheel.

    JKJ
    Last edited by John K Jordan; 05-19-2020 at 9:31 PM.

  7. #7
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    A hood behind the wheel with a dedicated shop vac that is wired to turn on with the grinder would seem like a good solution. Been meaning to build such a thing for a while now.

  8. #8
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    Quote Originally Posted by roger wiegand View Post
    A hood behind the wheel with a dedicated shop vac that is wired to turn on with the grinder would seem like a good solution. Been meaning to build such a thing for a while now.
    I think the OPs question was about the danger of starting a fire from sparks entering the DC, the hazard presumably the chance of igniting dust in the ducts or the bin. From the minimal sparks I've seen from CBN I suspect they would not make it to the bin or even set fire to dust caught in the ductwork. But I think concern about risk, however small, is wise. Would that assumed risk be the same with a shop vac? Perhaps one never used for wood dust?

    I wish someone would do a comprehensive study of this.

    BTW, the large fluff ball of steel dust I described being ignited was extremely close, within one inch of the bottom of the wheel. The few spark trails I noticed were "weak" and short compared to those from AlOx wheels. Maybe some people could grind with CBN on various tools in reduced light and report what they see.

    I wonder if a standard air cleaner would move enough air to remove the extremely tiny floating steel dust. I have one close I'll try the next time I sharpen lathe tools.

    JKJ

  9. #9
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    When I make tools and grind a lot in a day with CBN wheels I get those dust ignitions often. If there is a layer of steel dust built up on the table, the high carbon or more plain steels burn slowly, glowing red amongst the stainless and PMV-11 dust. I don't mind it, it's just a slow red ebbing pulse that moves through the dust in lines etc. The burning travels extensively through the dust, as far as there is dust there will be burning. Yes my table is rather scarred. Obviously it is cause for concern if you are using a shop vac for dust collection, I don't want that pretty red hot metal going in there.

  10. #10
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    Thanks for the ideas. I did a bit more search as well and I will attempt to make a guard using bottom section of a plastic pail, place a wet towel inside to capture dust as much as possible. I use a HEPA PAPR and an air filter so should be fine while grinding, but I still worry about fine dust hanging around post-grinding. I will look into magnets as well. Let me know if there are some magnets that are better suited for this purpose.

  11. #11
    If you get a set up that seems to work well, or is at least an improvement, please share, thanks!

  12. #12
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    I only recently got a grinder. I still just have the wheels it came with (not CBN). Is the dust from a "regular" grinding wheel less of a problem/danger vs. CBN?
    Admittedly, I never thought about dust control from the grinder until this thread...

  13. #13
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    Quote Originally Posted by Erich Weidner View Post
    ... Is the dust from a "regular" grinding wheel less of a problem/danger vs. CBN? ...
    I think it's worse. You will remove the amount of metal necessary for your tasks on either one. The friable wheels also release grit, to expose fresh grit to keep cutting, and will therefore create more dust. My impression is that the metal dust makes a mess, but is dwarfed by the abrasive dust with the friable wheels.

  14. #14
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    Friable wheels like Aluminum oxide are much worse. Without good dust control at the source and PPE you're basically breathing in the equivalent of ground glass. Once it gets into your lungs it pretty much can't leave, so it accumulates. I don't know the data, but I'd be shocked if it weren't a sufficient mechanical irritant to induce tumors over time. At best it will compromise lung function.

    I think the dust from CBN wheels gets more attention because it's black and much more obvious when it accumulates on surfaces. I'm sure it is also nasty to breathe, there's just less of it. There's at least some chance it will oxidize and dissolve away rather than accumulate in your lungs. I'd absolutely wear a mask when grinding with either sort of wheel.

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