Dust hazard

[Fred_Farkle]

Similar experiences? I saw the earlier thread about thermite grenades. The example in the link below seems kinda of worrisome.

http://www.hanford.gov/lessons/sitell/ll01/2001-36.htm

I think I will keep separate wheels/discs for Al and steel. And clean the shop a little better and more often.

Mike



[This message has been edited by Fred_Farkle (edited 02-11-2003).]

[docsteve66]

I suspect, this is a "urban legend" type story - despite it being posted on a gov site. Lee Valley catalouge described a simular incedent last year. This is not to say you should grind aluminum when safety regs say do not do. Both Lee valley and Hanover reports have lots of BTU (or calories) involved if true. The "thermite" is dispersed around the wheel, so is the iron. The temp has to be fairly high to ignite thermite, some way the heat has to travel from site to site, fast enough to stay hot enough to ignite. then the products have to obey the laws of physics- take a reasonable weight for the iron involved, and see what temperature the iron mustreach to have the calories or btu needed. With the small masses involved, the temp would be higher than a virgin whores expectations of income.

I have also read/heard of stones exploding after grinding aluminum. The explosion was supposedly due to the aluminum expanding and cracking the wheel.

Rip me a new one but use some facts and figures in the arguments- we don't vote on the laws of physics on this one
Steve

[Fred_Farkle]

Doc - Thamks for some clear thinking. After reading your post, the story does seem a little out of kilter.

Mike

[Thrud]

Well, Duh!

OF COURSE YOU should clean YOUR shop up - that way you can find stuff when it falls on the floor.

I am exempting myself, however.

[gramps]

I have a true story to tell about the danger of fire in the shop caused from fine dust
igniting.
I was given a piece of what I thought was
aluminum plate about 2 1/2 ft. sq.
I proceded to use my bandsaw to cut out
some parts. The blade in the saw was a fine
toothed one and I did not bother to change
to an aluminum blade.(mistake no 1)
I had no problem cutting the parts and went on with my project.
The next day I had to cutoff some 1/8" X 1" steel flat stock and stepped up to the band saw to cut them. the fine blade was still on
the machine so I started the the saw and realised that it was set for high speed to do the aluminum from the day before.
I decided to cut the steel without changing
the speed. (mistake no.2)
As soon as I touched the steel to the blade
it caused sparks and instantly there was fire
in the saw dust in the machine and on the floor around the machine ( it had been a while since I had swept up)
It turned out that the aluminum plate I had cut the day before was magnesium and the dust
from cutting that with the fine blade had ignited from the sparks off the steel.(caused from not slowing the blade to the proper speed for steel)
The fire was intensly bright and hot enough to ignite all the saw dust (a mixture of
steel, aluminum, cast iron etc.)
After a moment of panic I grabbed board and
was able to sweep most of the burnimg pile
out the door and avert disaster. (it was summer and I had the bandsaw right by my
garage door and the floor is flat..no threshold.
It was a scary experience and I tell this story on myself so others may avoid possible disaster. Your Gardian Angel may not be nearby as mine was.
Dave