HAZARD with CBN wheels

That's expensive solvent

Dick Coers

Up to 55% Hydrotreated light distillate (petroleum), and up to 40% Hydrotreated heavy naphtha. MSDS doesn't mention the last 5%.

Say what?

John K Jordan

I can't imagine what the cost of the diamond lapping fluid would have to do with a fire hazard warning.

Unless it's presence turned out to be germane to the hazard, lowering the risk of those with budget limitations. Seems a stretch.

Re: HAZARD with CBN wheels

Philip Duffy

Thanks for the informative warning! It never dawned on me that there was a fire hazard associated with my one CBN wheel. I will be paying close attention to the potential hazards and watch out for fire! Thanks again, John. P.

Re: HAZARD with CBN wheels

Barry Irby

Don't have a CBN wheel. Been reading about them, considering getting one.

Glad your problem wasn't any worse. Thank you for sharing this with us.

How does industry handle this? Surely there are industrial processes that create similar problems.

Could you use something for fluid that not only keeps the wheel clean buy also suppresses the danger of fire? I doubt water would help because it encourages rusting which is exothermic. Not sure "exothermic" is the correct word.

I was thinking of some sort of steel screen with magnets on it collect the particles out of the air. Your problem seems to negate this idea.

Re: HAZARD with CBN wheels

Reed Gray

I think I may have had some smoldering with my old aluminum oxide wheels, but that was more than 10 years ago. I don't think I ever have much build up though, or sparks. I was sharpening yesterday for a demo, and when done and loading the grinder, I noticed round dots on the wall where the sheet rock screws were. The particles are magnetized some how with the grinding process. I have noticed this before whti some 'fuzzy' tools that I left down by the grinder as I sharpened. I have a big belt sander (1 1/2 hp, 6 inch wide belt), and get shavings/dust up to 1/4 inch thick some times. Never saw any fire or embers.

robo hippy

Re: Say what?

Dick Coers

Just surprised with the ingredients when I looked up the MSDS. Kerosene and naphtha in a small bottle. Well maybe extra fancy petroleum and naphtha. No idea about the fire unless that fancy patroleum has extra wax.

Re: HAZARD with CBN wheels

John K Jordan

I think the problem at my grinder was actually the use of the magnet! The collected dust formed a big fuzz ball with longer tendrils of incredibly fine steel dust from the 600 grit wheel, most spread out so with lots of air. This fuzz ball was in the perfect position to catch a spark. On a coarser wheel I had no magnet so some steel dust collected on the table under the wheel - it was subject to lots of sparks but probably didn't ignite since it wasn't spread out in the air.

>>>I was sharpening yesterday for a demo, and when done and loading the grinder, I noticed round dots on the wall where the sheet rock screws were. The particles are magnetized some how with the grinding process. ...

It could be that the sheet rock screws themselves are magnetized instead of the dust. Perhaps the installer used a magnetized bit. You could test this by placing some bits of demagnetized mild steel (nuts, washers?) under a sheet of white paper near the grinder and see those spots collected more dust than the rest of the paper.

Also, some people have called me loony when I mentioned but it's a fact that steel can become magnetized just by sitting for a while in a magnetic field - even the earth's magnetic field is enough. There is a lot about this on the internet, some of it experiments for kids.

When something of the right kind of steel simply remains stationary it will slowly become magnetized, accelerated if tapped or vibrated. I first noticed by checking a refrigerator with a compass - it was one pole at the bottom and the other at the top. Cans on the pantry shelf were the same.

The worst in the shop is lathe tools. They will be become magnetized in use, I think because they are often held in about the same position and subjected to vibration from the turning. This gets annoying when sharpening with a dry CBN wheel on the Tormek where the wheel is rotating away from the tool edge. The tool will have a black trail of fine steel dust attached to the edge which obscures it and makes it harder to sharpen. I keep an old hand-held bulk tape eraser near near the grinders to demagnetize tools as needed. There is also a trick to demagnetize with a permanent magnet if anyone is interested.

I've been monitoring the fine steel dust floating around my shop with magnets placed in various places. It's amazing how far it will travel. Probably not beneficial to the lungs...

JKJ

Re: HAZARD with CBN wheels

mikeee12345

There are a number of metals and alloys that are pyrophoric (self-igniting) when they are reduced to a fine particulate size and exposed to moisture, humidity or chemicals. The finer the particulate the easier it is for the material to heat up from rapid oxidation and catch fire.

Re: HAZARD with CBN wheels

John K Jordan

>>>Could you use something for fluid that not only keeps the wheel clean buy also suppresses the danger of fire?

There are honing fluids that you mix with water - I have some of this but haven't tried it yet with CBN. It will not cause rust (I use a similar cooling/lubricating fluid with my horizontal metal-cutting bandsaw.

https://www.amazon.com/gp/product/B00F5XTWL0

My plan is to position a dust collector pickup nozzle behind the wheel. I've been reading up on spark arrestors, commonly required in off-road motorcycle mufflers and in chainsaws in some areas. Most consist of a simple metal screen. I'm imagining the strong airflow from the cyclone may pull sparks through a simple screen so I want to experiment with multiple screens and perhaps a baffle. I think I can set up a test stand with a clear plastic tube and watch the sparks in the dark and see what it takes to stop them. One promising thing is a glowing steel particle from a grinding wheel doesn't travel very far before it burns out. It may be that a vertical run with screens and baffles would do the trick.

Researching industrial requirements and solutions is on my list. I'm not all that interested in burning the shop to the ground.

JKJ

Re: HAZARD with CBN wheels

mikeee12345

There are a number of metals and alloys that are pyrophoric (self-igniting) when they are reduced to a fine particulate size and exposed to moisture, humidity or chemicals. The finer the particulate the easier it is for the material to heat up from rapid oxidation and catch fire.

Re: HAZARD with CBN wheels

lyle Jamieson

I suggest you share this with more turners. Please do an article or safety note for AAW.

Re: HAZARD with CBN wheels

George Balock

Thanks for the heads up John. I will be more diligent in checking my magnets!

Re: HAZARD with CBN wheels

David Gilbert

Interesting and useful information. I'll keep an eye on my magnets.

Here is another thought. If these little pieces of steel dust are floating around my shop and getting caught by my magnets, then my lungs are probably catching some of them as well. I try to remember to put on my dust mask before grinding my tools to protect my lungs. I have a LED light on my grinder and I can see some of these little particles in the air when I'm sharpening. This is especially true with the 600 grit CBN wheel.

Be careful and be safe.

David G

Re: HAZARD with CBN wheels

Reed Gray

I don't remember if I have pictures or not in my CBN wheel article on my web site, but I had some of 'fuzzy' tools. Laying the gouges next to the grinder where metal dust was accumulating, when I picked them up, some had full beards, like mine.... Could be a number of reasons. Looks like there is still a lot to learn about dealing with grinder dust. I never considered magnets to be a good solution for the CBN wheel dust....

robo hippy

Re: HAZARD with CBN wheels

mikeee12345

Spontaneous Human Combustion caused by wood turners not using dust control equipment. :-)

Re: HAZARD with CBN wheels

Jim Barbour

Thanks for the information John. Do write it up and send to the journal, and elsewhere, to get the word out.

Re: HAZARD with CBN wheels

John K Jordan

>>>Do write it up and send to the journal, and elsewhere, to get the word out.

That's a great idea. I have only one free day in the next few week but when I get back in the country in October I plan to do some of the tests I mentioned to get my facts straight. I also want to get some good pictures of a magnet fuzz ball and a smouldering HSS powder fire in progress with a closeup of the glow. (It actually looked kind of "cool".) That might catch help to catch attention.

For now I've picked up all the metal dust around the grinders (and saved it in a plastic bag for some experiments.)

I also posted this on Sawmill Creek. I don't spend time on the AAW forum but maybe someone who does could copy the gist of this there.

JKJ

Re: HAZARD with CBN wheels

Peter Hyde

I suspect the cause of the problem is in fact using a petroleum based honing fluid.

I run my wheel dry and if it needs cleaning there is a cleaning stick I purchased from Packard that does a quick cleaning with no spray of inflammable liquid.

I suspect not

John K Jordan

>>>I suspect the cause of the problem is in fact using a petroleum based honing fluid.

I don't think so. There was just a smear on the wheel and no fluid dripped on the magnet. I tried a quick test and dry iron dust from another wheel that has never had honing fluid ignites and burns nicely. A further experiment might show if honing fluid accelerates the burning, slows it, or makes no difference.

I found years ago that fine steel wool burned fine by itself. It makes an interesting science experiment - this guy ignites it with a battery:

http://www.untamedscience.com/blog/steel-wool-science/

JKJ

Re: HAZARD with CBN wheels

TomD

Came close, but never bought a CBN wheel, however in knife grinding the metal spray is caught in a bucket with water.

Re: HAZARD with CBN wheels

mikeee12345

The creation of sparks from metals is based on the pyrophoricity of small metal particles, and pyrophoric alloys are made for this purpose.[2] This has certain uses: the sparking mechanisms in lighters and various toys, using ferrocerium; starting fires without matches, using a firesteel; the flintlock mechanism in firearms; and spark-testing ferrous metals. Pyrophoric materials are often water-reactive as well and will ignite when they contact water or humid air.

Re: HAZARD with CBN wheels

John K Jordan

>>>Came close, but never bought a CBN wheel, however in knife grinding the metal spray is caught in a bucket with water.

With heavy grinding on the 80 grit CBN the sparks are carried around on the surface of the wheel and fly off at random places. No good way I can think of to catch them with water.

JKJ

Re: HAZARD with CBN wheels

John Jordan

Put a guard with a port in back on it, assuming it doesn't have one. Maybe yours does, I can't remember. I'm not a fan of leaving the guards off for several reasons, all mine have guards. If one has the wide wheels, a few spacers and some duct tape or a plywood filler/spacer will allow the guards to work. I use a catch can, but have a water-filled small vacuum I intend to hook to all four of my grinders.

Like many things, cleaning up will prevent the problem.

Re: HAZARD with CBN wheels

John K Jordan

Good ideas. I mostly wanted others to be aware of the potential hazard. See you soon.

JKJ