Grinder dust collection

[john lucas]

I've been concerned about breathing the dust from my grinding wheels for awhile now. It's not too bad when sharpening but when you clean or true up the wheels it's terrible and this is dangerous dust.
I built a dust extraction system this week and connected it to a dedicated shop vac. I have looked at the fire hazard issue and really don't think there is one. I find it hard to believe that a spark would stay alive traveling down the hose and would certainly not be hot enough to start the plastic on fire. I am a little concerned about the foam filter inside and will watch that for scorch marks very closely for the first month or so.
I'm going to find a piece of scrap steel that will produce a lot of sparks and grind the heck out of it just to see. Since this shop vac is dedicated to this task there won't be any flammables inside except the filter.

 

[Mark Mandell]

Addition

John,

I suggest you put (hot glue) a piece of sheet metal on the inlet baffle inside your vac. That will prevent still-hot particles from hitting the plastic or your filter.

To get extreme, you could also make an interim separator out of a 5 gal bucket into which you can put a quart or 2 of water. With this you can also fabricate the separator inlet to feed in under the water surface, creating what's called a water filter, so that the dust stays in the water. Draw back here is that you'll be adding water vapor to your shop and you'll have to clean out the "mud" from time-to-time.

Good idea.

 

[Dick Sowa]

Regardless of what precautions you take with the vacuum itself, the hot sparks will still have to travel through the plastic hose to get there. I would be more concerned about what might collect in the hoses before it has a chance to cool down.

 

[jwtaylor]

Regardless of what precautions you take with the vacuum itself, the hot sparks will still have to travel through the plastic hose to get there. I would be more concerned about what might collect in the hoses before it has a chance to cool down.

You might be able to use the expandable aluminum heat riser tubing from the heat riser inlet from an older (much) car air cleaner. You used to be able to get this from the auto parts store, you may have to search for it now days.

There is also an version of dryer vent hose that is expandable aluminum but the 4" diameter is to large I would think.

 

[Glenn Barber]

John-Did your grinder already have the "extraction ports" built-in to the machine? Did you have to modify the grinder to accept the extraction system?


Glenn

#37539

 

[Bill Boehme]

John, my Delta grinder has built in dust extraction ports at the lower back of the shrouds and they are connected together by a manifold with a T in the middle to connect a shop vac. The only problem is that the size does not match any shop vac size hoses. I rigged up some PVC plumbing fittings and silver duct tape to get things to fit. By the time that the abrasive and metal particles travel the approximately eight inches to the plastic conector there is no longer any significant amount of ignition source. If there were flammable fumes in the hose at about the stoichiometric ratio to air, then there might be a nice explosion, but there is nothing to burn in this situation as opposed to a dust collector hose carrying sanding dust away.

 

[Jake Debski]

John, FWIW department, a good friend and very active turner I know has a 7" Baldor grinder. He rubber bands cotton socks to the outlet ports. He has been doing this for years with no problems, and almost no grinding dust at the grinder station.

 

[Owen Lowe]

John, my Delta grinder has built in dust extraction ports at the lower back of the shrouds and they are connected together by a manifold with a T in the middle to connect a shop vac. The only problem is that the size does not match any shop vac size hoses. I rigged up some PVC plumbing fittings and silver duct tape to get things to fit. By the time that the abrasive and metal particles travel the approximately eight inches to the plastic conector there is no longer any significant amount of ignition source. If there were flammable fumes in the hose at about the stoichiometric ratio to air, then there might be a nice explosion, but there is nothing to burn in this situation as opposed to a dust collector hose carrying sanding dust away.

Bill can always be relied upon for words like stoichiometric!

John, you could fill the shop vac with a couple gallons of water and make sure the inlet is aimed downward towards it. I've seen some folks who pull the vacuum through a separator bucket of water.

 

[john lucas]

The exhaust ports were already there. I just cut a square to fit the opening and then drilled a hole through it. I'm pretty sure the sparks won't travel far enough with enough heat to do any damage. I've used an angle grinder a lot to grind steel with hundreds more sparks than I'll ever get out of my white wheels and HSS. No problems so far. Now sparks from welding is a different matter.

 

[Bill Boehme]

Bill can always be relied upon for words like stoichiometric!

John, you could fill the shop vac with a couple gallons of water and ...

I've been waiting for years for the right opportunity.

When I was in an airplane partnership a number of years ago, we had the good fortune to have a partner who was an AI (airframe inspector -- the highest level certificated¹ by the FAA to do both airframe and powerplant maintenance and modifications as well as officially certify the work once completed). I got to read lots of books on powerplants (meaning aircraft engines) and fuel systems. Stoichiometric was one of those words that I had not used since college chemistry. It was good to learn that there actually was a real-world practical use for it.

The exhaust ports were already there. I just cut a square to fit the opening and then drilled a hole through it. I'm pretty sure the sparks won't travel far enough with enough heat to do any damage. I've used an angle grinder a lot to grind steel with hundreds more sparks than I'll ever get out of my white wheels and HSS. No problems so far. Now sparks from welding is a different matter.

Sounds like your grinder is the same model as mine. The only thing that I don't like about mine is the big ring at each end of the motor that interferes with sharpening long blades
-------------------------------------------
¹ No, it is not a spelling error. The FAA is the only place in the world as far as I know that used the word "certificated" insted of "certified".

 

[MichaelMouse]

Sorry, the solutions are worse than the problem, as I see it. I think the good old inverse square rule will keep your lungs safe, unless you stick your nose down into the flute of the tool in progress. Stand up, pull your nuisance mask down to deflect anything that climbs, if you're so inclined, and let the dust accumulate where it will. Gravity is your friend.

 

[Greg Keddy]

Gravity is your friend, but depending on the particle size (which I don't know of the top of my head) the dust will remain airborne for plenty enough time for you to breathe it in, even after you have shut off your grinder. If you're worried about breathing in dust, gravity alone wont stop that in any reasonable amount of time. A good mask will go a long way, and using a water grinder will go even farther. Granted, they are quite a lot slower for reshaping, but the bulk of the grinding you likely do is sharpening, not shaping.

MM,

Not sure what you mean by inverse square rule, but Stokes Law predicts extended settling times for particles in the 0.1 - 2 micron range, which are the most dangerous for people to breathe in.

 

[Bill Boehme]

Sorry, the solutions are worse than the problem
...

I'm scratching my bald head trying to understand what part of collecting the grinder dust and grit makes it worse than doing nothing.

My opinion is that sucking up some of the dust is better than letting it settle all over everything within about three feet of the grinder as well as generating a cloud of fine dust that extends even further.

I am only six feet tall and my knuckles are just short of dragging, so my reach is not quite sufficient to avoid the cloud. My hat's off to those who can. If I use the grinder without the shop vac, it invariably sends me into a coughing spasm.

I should add that I currently use Norton 3X wheels and they seem to generate a lot more really fine dust that hangs in the air as opposed to the much more friable basic AO white wheels that produce a lot of grit.

Since my grinder came from the factory with the dust collection plumbing built into it, there is no special effort needed to have a slaved shop vac start up whenever the grinder is turned on. For other grinders, a home brew modification to add dust collection is simple enough.

... Not sure what you mean by inverse square rule, but Stokes Law predicts extended settling times for particles in the 0.1 - 2 micron range, which are the most dangerous for people to breathe in.

I had the same thought. We're not dealing with field strength of radiated emissions on a sphere surrounding an isotropic radiator as MM's statement seems to imply. This is a completely different situation involving the movement of fine particles in air.

 

[MichaelMouse]

You guys spread dust? Mine falls on the table below the wheel, actually it's driven into it by the rotation. First sign of a spark down the flute, or potentially up, means grinding's complete.

As to the inverse square rule, it means that the chance that you can find a particle to inhale diminishes exponentially with the distance from the point of production. Nothing more than that. Or do you produce airborne dust and try to keep it airborne with an air source directed at the deposit zone?

Much ado about nothing, while a spark in dust can certainly cause big trouble. I was still in the basement when the "cold sparks" from my ceramic thrusters on the bandsaw got the beech dust smoldering. Sure glad I was.

 

[Greg Keddy]

You guys spread dust? Mine falls on the table below the wheel, actually it's driven into it by the rotation. First sign of a spark down the flute, or potentially up, means grinding's complete.

As to the inverse square rule, it means that the chance that you can find a particle to inhale diminishes exponentially with the distance from the point of production. Nothing more than that. Or do you produce airborne dust and try to keep it airborne with an air source directed at the deposit zone?

Much ado about nothing, while a spark in dust can certainly cause big trouble. I was still in the basement when the "cold sparks" from my ceramic thrusters on the bandsaw got the beech dust smoldering. Sure glad I was.

Dust spreads all by itself. Just because you aim it at something doesnt mean it stays there once it impacts the surface, quite the contrary. Some of the large particles certainly end up depositing on the table, but the smaller particles will not and depending on the orientation of your dust exhaust, and the air currents in your shop, will wander around in the air for a long time. My grinder exhausts parallel to the table to which its bolted and you can watch the dust billow up when you are truing the wheel. Ignore that fact if you want, but you'll be breathing the dust in if you do.

I am not sure if your comment about an air source to keep dust suspended was facetious, but I will assume so.

 

[MichaelMouse]

The secondary source of air would be - the exhaust from the vacuum. Unless you're locating it outside.

 

[john lucas]

I do get a lot of dust on the base of the grinder but there is an awful lot that floats for a few minutes. I can hold my breath for a minute and half but really prefer not to have to do that. I don't look as good with a blue face. Who knows what's floating around that I don't see.

 

[dbonertz]

John,

Do you have an update on how it is working? I am curious since I have been thinking of doing a similar thing. I don't notice the dust so much when grinding a tool but that does not mean it isn't there. But when dressing the wheel I can smell it in the air which I am sure if I can smell it then dust is in the air.

Dale

 

[Gretch Flo]

Grinder dust

MIchael - As John mentioned when he started the thread, the TRUING UP generates alot more dust-that is my experience. (but no sparks) with my white wheels. I just don't breathe. Not so with the metalic particles, which fall downward. -Gretch

 

[MichaelMouse]

So what do you figure, if you put your nose close down there, a year's worth of dust -likely sanding, not inorganic solid, aerodynamics being what they are - would constitute the same dose as an hour at the beach? Ten years for an afternoon at the dirt track races?

One danger is pretty well known, and that's wherever sanding dust settles, a spark can start a smoulder or fire. As I said, I think collection at production is a solution in search of a problem. I also don't hold with the belief that keeping sanding dust airborne long enough to get into a ceiling-mounted collector is for the benefit of the nose, but the broom.

 

[dbonertz]

MM,

I am trying to understand your beef on dust collection. Dust particles per unit increase as you sand, grind or such activities which increases the volume one breathes in. Gravity works but every room has a certain air flow which keeps dust moving for awhile before settling. Why not try to collect them at the production source rather than let gravity alone drop them to the floor or bench, all the while breathing in more particles than necessary. One will need to deal with the settled dust sooner or later and if later one is always disturbing it thus adding unnecessary particles to the air. Also, if using a shop vac to collect it can actually be worse if not using a very fine micron filter to keep from putting particles back into the air. When I sand, for instance, I run a dust collector which grabs the bulk of the particles at the production source and I also run an air filtration system to collect the residual particles in the air for shop cleaning and air quality purposes. My dust collector is located in its own room outside my shop thus adding no particles from the filter.

If John or anyone else collecting grinder dust takes the correct precautions they should never experience a fire and has rid themselves of potentially harmful dust particles. They can also help keep their shop a little cleaner from settled dust and with the side advantage of not having as much dust to disturb or distribute as they work/play. There is nothing wrong with collecting dust at the source but many benefits.

 

[Mark Mandell]

Reading For Extra Credit

nj.gov/health/eoh/rtkweb/documents/fs/2891.pdf

Copy and paste in your browser.

 

[john lucas]

Thanks Mark. That's exactly why I did this. To answer MM questions. When the sun comes through my window in the late evening you can see every grain of dust that floats in the air. The grinder dust stays in the air surprisingly long. It is so small and light that I can hold a shop vac hose about 3 or 4 feet from the cloud and you can watch it suck it in. I'm pretty sure I would be breathing that stuff.
That's also why I'm redoing all the dust collection in my shop. At least as soon as all the stuff I ordered gets here.

 

[Mark Mandell]

That's exactly why I did this.

I knew that.
It's also why I did the same thing in my basement shop. I do, btw, run mine through the water "filter" I described. All I do is rinse the bucket out every couple of weeks. The water captures the really fine stuff and shopvac stays clean.

 

[dbonertz]

Mark or John,

Have you tried just putting water in the holding tank of your wet/dry vac only. Mark, I see you use a separate five gallon bucket between the grinder and vac. I would like to know how it works directly in the vac with water. I have limited space and value every inch. I too am redoing my wood dust collection system when I get the time (biggest issue) and material. I really want to collect the grinder dust also so John's post was quite timely. I have a $500 hepa vac that I had to purchase for my contracting business that hardly gets used for lead paint, it's intended purpose. Would like to use it with water in it if your experience shows it works.

Thanks in advance,

Dale

 

[Mark Mandell]

Hi Dale,

The water filter is very easy to make. I used a clean 5gal. bucket with lid. Fit a 2-1/4" shopvac fitting into the center of the lid. Drill a second hole toward the rim of the lid and fit a piece of PVC pipe that goes down to about 2" above the bottom of the bucket in a size that will take the collection hose from your grinder. Put 2 gals. or so of water in the bucket, snap the lid tight. Make sure that the fittings are sealed at the lid so you don't loose vacuum pressure. Hook up your hoses (from the "Y" and the vac) and you're ready to go. I'm attaching a pdf drawing as I don't have a pic.

Since you mentioned wood dust, I'll note that this is not good for organic material dust collection. Wood dust and chips will mold, mildew and/or breed other nasty stuff in the water in no time and present a health hazard.

Let's also remember that there will be evaporation of the water as the air is drawn through the filter. This means that you'll be adding moisture to the air in your shop, and also that you'll have to add some water from time to time. When I'm turning and using the grinder, I usually clean the
water bucket once a week or so.

Couple of caveats here as well. Your grinder's wheels need to be enclosed as much as possible. Unless you go all out in some way, your collector will miss some of the dust that flies straight down in front from the contact point. You could try catch this small amount in a small water pan along the front of the grinder, but I haven't bothered with that.

PS: I would not put water in the shopvac. A- because the water only works if the air stream is bubbled through the water (won't happen in the vac tank), and B- because of the mold, mildew, and other stuff problem; go this route and you'll likely trash the vac due to the stink.

PPS: Sorry,forgot something. The filter is more effective when the air bubbles are smaller. If a mesh, like window screen, is put over the bottom of the intake tube (under the water surface), it will act like an aerator. You just have to play with the screen size so that it doesn't clog with dust particles, and it, too will have to be rinsed off from time-to-time. You can make an "air cap" by drilling a bunch of 1/8" holes in a PVC end cap. Easy to remove and clean.

 

[dbonertz]

Thanks Mark,

I am adding to my wood dust collection system and redoing part of it. The grinder dust collector will be an entirely separate unit. I was hoping the water in the vac itself would work just because of the space constraints. I'll figure out a bucket location to make this work. The humidity from the bucket/vac will be welcome since we are dry here in Colorado. Besides I rough turn wet bowl blanks regularly so my shop fluctuates with high and low humidity all the time. I have two Delta 8" slow speed grinders (long story but got two for the price of one) which come with dust ports on the wheel covers. I have them mounted side by side on a bench and intend to hook all four ports to one collection system. Thank you for taking the time to respond.

Dale

 

[Frank F]

I've been thinking about ways to collect grider particles for some time, especially when wheel dressing. But also to keep the grinding area clean.

Although many grinders have provisions for vacuum connections, to my surprise I've found little info regarding vacuum requirements or specifications.

Hot sparks plus a concentrated air environment (the vacuum hose) could present a fire hazard. I did find references to "spark arrestors" which indicates that this is an issue. But I'm not sure how they work.

Does anyone have experience with spark arrestors?

Frank

 

[Matthew Clarke]

Use a water cooled sharpening system and all of these troubles go away!

Matt

 

[John Torchick]

Stoichiometric

I took chemistry in high school and college. Never heard of the word. Maybe that was when I was asleep or looking the girl sitting next to me.
I use a box fan and pleated furnace filter in the shop to catch a lot of dust. Surprising how much this catches. The Mrs. saw it on HGTV once. Shop Vac jimmy-rigs are also used.

 

[egsiegel]

Use a water cooled sharpening system and all of these troubles go away!

Matt

there goes Matt buy more toys again

 

[Dean Center]

I took chemistry in high school and college. Never heard of the word. Maybe that was when I was asleep or looking the girl sitting next to me.
I use a box fan and pleated furnace filter in the shop to catch a lot of dust. Surprising how much this catches. The Mrs. saw it on HGTV once. Shop Vac jimmy-rigs are also used.

You and I had chemistry at the same time, dripping things into beakers and watching the color change, dipping wands into solution and flaming them. We're dinosaurs. Chemistry lab now means you get on the computer and analyze 3-D structures that reflect energy state and binding sites. It's a whole 'nuther world, Gramps.

 

[hughie]

[

I built a dust extraction system this week and connected it to a dedicated shop vac. I have looked at the fire hazard issue and really don't think there is one. I find it hard to believe that a spark would stay alive traveling down the hose and would certainly not be hot enough to start the plastic on fire. I am a little concerned about the foam filter inside and will watch that for scorch marks very closely for the first month or so.

I doubt very much if there is an issue here with fire. Sparks are very hot but lack mass.
Industrially I have connected both linishers 4"x4' belts and large grinders 12"x2.5" with double wheels to a extraction system with no ill effect. Its been running for around ten years now.

 

[MichaelMouse]

[

I doubt very much if there is an issue here with fire. Sparks are very hot but lack mass.

I'd agree, Hughie, were it not for the two - yes, I'm that dense - smouldering episodes I experienced when I transitioned to ceramic thrust "bearings" on my bandsaw. Granted, the offending tinder below the table insert was dust from spalted beech. The manufacturer says they're "cold" sparks, but apparently they got close enough to that Fahrenheit 451 to light off. I know I pay a lot more attention to what accumulates under the table now than I used to. If my nose had exited the shop, I might have lost it all.

Longer time in the air, more likely they'll burn out, no doubt.

 

[Matthew Clarke]

there goes Matt buy more toys again

Ed, If someone has already solved the problem, why recreate the wheel? There is another alternative, just don't sharpen your tools!

Matt

 

[Steve Mills]

dust counts from grinder

I have a Dylos dust counter. The counter runs for to very high count whenever I use the grinder. The number runs higher than running any other machine even without the dust collector. For example, running the table saw or drill press or lathe generates counts of approximately 400 or 500. Using the grinder genrates counts of 2000 and above. This is in a shop where the counter is 20ft from the grinder. This is specifically for particles in the 0.5 micron range. Since the grinder is generating ceramic particles, they are likely very hazardous. It do wish there were suggestions on how to control this dust at the source.

If I add a vacuum hose, it would miss the bulk of the particles being shot out the front of the grinder. The larger particles are seen as the sparks.