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robo hippy
27th May 2014, 01:00 PM
I made an interesting discovery today. I have had the CBN wheels for years. I took a Moffat (brand name) lamp down off a shelf that was about 30 inches above my grinder. It was still in the box, one of the kind with the 1/4 round dog ears on the lid that tuck into the side of the box to close it, but not taped. I opened up the box to check on the lamp and found a ring of fine metal dust on the smaller box that had the magnetic base in it. I had always thought that the metal particles were too coarse and too heavy to float around like that. Ralph Lindburg, a turner from up in Washington said that when he was in the Navy, full respiratory protection was required for any metal grinding or chipping.

Some thing to ponder....

robo hippy

Old Croc
27th May 2014, 02:15 PM
Have to agree with you Robo, be carefull with metal dust, especially anything that is Chromed. I have read this dust is one of the worst to inhale, thats why I love my Tormek.:2tsup: I have considered getting a CBN for it for rapid removal of material when required.
rgds,
Crocy.

BobL
27th May 2014, 03:46 PM
I have done some measurements on metal dust when using cutting wheels.
The results are posted here.
http://www.woodworkforums.com/showthread.php?t=183111

There's been a some studies of the effects in working environments that show some problems but I don't think the metal is a problem for DIY'ers compared to the binders and reinforcements used in grinding and cutting wheels.

Mobyturns
27th May 2014, 09:26 PM
I made an interesting discovery today. I have had the CBN wheels for years. I took a Moffat (brand name) lamp down off a shelf that was about 30 inches above my grinder. It was still in the box, one of the kind with the 1/4 round dog ears on the lid that tuck into the side of the box to close it, but not taped. I opened up the box to check on the lamp and found a ring of fine metal dust on the smaller box that had the magnetic base in it. I had always thought that the metal particles were too coarse and too heavy to float around like that. Ralph Lindburg, a turner from up in Washington said that when he was in the Navy, full respiratory protection was required for any metal grinding or chipping.

Some thing to ponder....

robo hippy


Robo,
The Navy probably also used paint formulations that civilian users could not use i.e. lead oxides etc. Siderosis associated with iron dusts from grinding is a risk along with from eye, facial & contact injuries. It is essentially changes in body tissue due to the uptake of iron in the lungs, eyes etc. There is mounting evidence to suggest causal links to cancers previously attributed to smoking, welding fumes etc in iron workers. http://www.ccohs.ca/oshanswers/chemicals/lungs_dust.html is a site worth visiting if you are interested.

robo hippy
28th May 2014, 04:57 AM
BobL,
Interesting bit you posted here. I am wondering, since you used a cut off wheel, how much of the particulate is metal, and how much is the wheel? I haven't used a cut off wheel much, other than in days doing concrete construction, and we would use gas powered cutters with an abrasive wheel on them. Lots of both metal and wheel dust.

Nice bit of info there.

robo hippy

BobL
28th May 2014, 09:40 AM
BobL,
Interesting bit you posted here. I am wondering, since you used a cut off wheel, how much of the particulate is metal, and how much is the wheel?

Yep I'd like to know that as well but there is no simple answer.
In total there was 10 times more mass of metal grit /dust generated than wheel grit/dust
The dust for both the metal and the wheel consists of a wide range of dust particle sizes.
Most of the large metal and wheel dust particles will fall to the ground immediately (if not we are really in trouble).
The remainder of the metal and wheel dust particles will stay suspended in the air for varying amounts of time depending on the weight of the particles.
Initially there is more metal dust than wheel dust in the air.
After about 5 minutes most of the (heavier) metal dust particle will have settled out of the air but there are still more than 3,000,000 particles of metal and wheel dust particles per cubic ft in the air and it takes hours for these to settle.
There must be some metal in this fine dust as you observe but I cannot distinguish between these fine metal and wheel dust particles with my dust meter. To determine this would require the dust be filtered from the air and have something like Electron Microscopy performed on them (i.e. $$$$$)

So you see its a dynamic situation with varying amounts of metal and wheel dust or different sizes in the air at any one time.
Initially the dust will be dominated by metal but later in time it will be dominated by wheel dust.
There is also a likelihood of a combo of the two, i.e. wheel dust with metal attached/impacted/abraded to it