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Mark J

Grinder Dust Collection

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Looking for some dust collection solutions at the grinder.

I have a grinder with CBN wheels and sharpening produces a good bit of particulate steel debris.  I was starting to ponder how to do DC, but was thinking maybe this problem has already been solved.  

My set up has two CBN wheels with the guards removed.  I was thinking about a hose clamp to position either the shop vac hose or 4" DC hose near the bottom of the wheel.

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Yeah this screams fire risk to me. I think the best way to deal with it is let the stuff cool and vacuum it up after the fact. Or build a housing around it if possible to contain the mess.

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Many knifemakers I've seen just position a bucket below the grinder to catch the majority of the particles. Some keep a little water in it.

Steel particles are a bit heavier than wood dust, and don't tend to float around in the air as much.

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I put a wet paper towel under the wheel, and it catches a lot of it.  I think most of us that use CBN wheels have the guards removed, mainly because the wheels don't fit in the typical grinder guard.  I'm sure it's still nowhere near the detritus created with a friable wheel though.

Even so, I'm going to go back to wet grinding, as soon as I see enough positive reviews of the Tormek diamond wheels.  I can't dry grind in the houses I work on, so the grinder has to be kept outside.   I'll never go back to friable wheels though, for woodworking edges. 

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1 hour ago, Chestnut said:

Yeah this screams fire risk to me. I think the best way to deal with it is let the stuff cool and vacuum it up after the fact. Or build a housing around it if possible to contain the mess.

Oh yeah, there's that.  Glad I asked.  CBN's don't make much sparks, but there's some.  So on to plan B, then.

Damp paper towel is easy.  Would there be such a thing as sticky paper?  I am thinking of a smaller version of the sticky foot mats you see at construction sites.

I was also thinking of a tray under the wheel, removable and easy to dump, could have a bit of water in the bottom.

What about one of those strong magnets?  I could put it in a small Ziplock and leave it under the wheel.  Then periodically peel off the bag to discard the fillings.

@Tom Kingthey do make a CBN wheel for the Tormek (e.g. Woodturning Wonders), but it is  supposed to be used dry.  Can the diamond wheels be immersed?

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Mouse trap pads?

I wonder if a pan with grease would just end up making a mess inadvertently? Might catch better than water long term because it wn't evaporate but bump it and instant mess.

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Maybe one or two of those big Rockler silicone glue mats would contain it all and be able to be cleaned up whenever necessary?

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Well here's what I've come up with so far.  I decided to pursue the sticky door mat idea.  I bought "Step N Peel" from Menards.  It's $20 for 30 sheets. The sheets are 24 x 30 inches so that can be cut into 6 smaller pads (the material cuts easily).  The product comes with 30 numbered tabs on one corner that have no adhesive, so you have a  place to grab the expended sheet when pulling it off.  

Thing is it's impossible to pull off just one sheet without the tab.  So,before cutting them out, I laboriously peeled back the edges of each sheet to put my own paper tabs in the corners of my smaller pads.  Well, I dd 15 sheets before I got tired of it and decided to just try what I had.  After all it might not work.   Here's a couple of pictures showing the pads in place. 

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I have to say it worked pretty well.  Here's an after use picture.  You can see the faint haze of metal particles.  

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The metal particles appear well adhered to the pad, but after one use I think the pad may be saturated.  There's not much stickiness left right under the wheel.  And some particles fly out beyond the pad, so there's still that mess.  Overall it's very much better than nothing, but the damp paper towel may be just a simpler solution.  I'll keep goofing with this idea and see where it goes.  

One idea that crosses my mind is to just use the whole floor mat pad.  Put the pad on a board, then place the grinder on the pad.  The pad should be big enough to collect most of the debris.  You would have to pick up the grinder every time you changed sheets, though.  

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How much space do you need under the wheel could you make a chute that goes back to a container and then just empty that? I know it's complicated to build but ..... it might be worth it? OR even get one of the  slow and narrow DC shrouds and have it dump on a blast gate then just open the gate to empty it into a container?

Now that I see a picture it's making a lot more sense.

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Don't need much space under the wheels or below the tool rest bar.

I want to contain the dust and keep it from contaminanting my work area.  The idea is to keep the sharpening station near the lathe for frequent tool sharpening, but the grinder is a lot more messy than I had given it credit for.

After I go through these adhesive sheets I may try fashioning  collection trays from aluminum pie pans.  That would require eating some pies, but some sacrafices have to be made in the interest of woodworking science.  

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Maybe I'm missing something, but why not just put a box around the grinder, since this looks like a permanent setup? You could leave the front open, and enclose the sides, back, and top, leaving maybe 1" clearance from the wheels. I'm assuming you really only need access to the front portion of the wheel. If you're worried about fire risk, make it from sheet metal or just line the lower part of the inside with sheet metal. It would keep it all contained, and you could just vacuum it out periodically. It's probably not all that much work to build (you could try it with cardboard to see if it works) and it wouldn't require any ongoing effort.

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I like the idea of building walls around the grinder.  That could be easily done with cardboard and I don't see any real fire risk with CBN's.  

But it's looking like the magnet idea might have some merit.  All I had in the way of rare earth magnets were 3 quarter size magnets.  But I had to touch up one of my tools today so I put them into so some zip lock bags and replaced the sticky mat with the magnets.  

Here's a picture after sharpening the tool.  Wasn't that much metal taken off, but you can see the dust sticking to the front and bag magnets.  The side one didn't do much.

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There was surprisingly little dust in between the bags, but this was easy to sweep up with the magnets.  Took them over to the garbage can and removed them easily from their bags whereupon the metal dust fell into the can.  Re-used the bags.  

I am going to goof with this some more and see where it goes.  Next time I may put all three magnets under to wheel.  I will look for a 2 inch long bar.  I would suggest freezer weight ziplocks, too.  The magnets stick to each other and other things like the metal base of the grinder (fortunately the  wheel is aluminum) and it takes a lot of pulling to get them apart.  

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After a little research I decided to stick with the little magnets I have.  The pulling force of these things seems to go as the volume.  The little bars I saw had like ten pounds of pull which seemed like a lot for this application.  

Today I did try using a collection tray as well as one of the magnets.

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You might want to use something less valuable than this hand formed aluminum vessel with vintage patina, but the idea worked well.  It gives better reach out in front of the wheel.

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I wonder if an ash vacuum would be better/easier to empty. I imagine it will take you a while to fill up 14 gallons of steel dust.

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I just vacuum with a round nozzle after the particles have cooled...usually an hour or more when I do the whole shop. I don't vacuum right away after sharpening.

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I'm giving up on dry grinding, and going back to a wet grinder, for this type of grinding.  One like I want is not made, so I'm planning to cobble one together myself.  I don't want to give up on the non-diameter changing advantage of the CBN wheels, so the plan is to go with wet diamond wheels.  I had given up thinking about it for a while, but this weekend I saw (new to me) reversing servo motors for commercial sewing machines, which solves the previously very expensive variable speed reversing motor problem.  The sewing machine servo motors are less than a couple of hundred dollars for a nice motor, and controls.  There will have to be a belt drive to a spindle holding a couple of wheels.  My sharpening sink is 92" long, so it can sit on that drainboard.

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Beings that we are having grinder discussions. Low speed grinders show up a lot for sharpening tools. Is there a point to have a high speed grinder around if I'm never going to do metal work? Could i use the low speed grinder for other grinding tasks like sharpening my mower blade or taking a 1/4" off of a screw?

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My answer is yes.  In fact I'm not sure what a high speed grinder would be for.  The 1750 RPM of a "low" speed is already fast and more than aggressive enough.  

Tom, I don't blame you one bit.  It's the best dust containment system, and it's great to be able to flush the debris away. 

But wet grinding when I have to reshape a heavy metal tool just exceeds my patience.  And faucet and sink are some distance away for me.  

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Low speed grinding with coated metallic wheels (almost) eliminates a huge safety hazard from the shop, too. A grinding wheel exploding in your face is rather unpleasant.

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