TOY: Re: Safety Issue

[Thomas Bank <trbii@xxxxxxxxxxxx>]

Yes, thermite welding exists.  I have been around to witness it. 
VERY impressive!

That said, I sort of have to wonder about this story.  First, you 
would need a substantial amount of each powder -- more than I think 
you would have available in a grinding disk.  I have always been told 
not to use the same disk for different metals for the reason 
mentioned before -- contaminating the current metal with some metal 
from a past use.  One specific one is to not sharpen your tungsten 
electrode on a stone used for any other purpose -- you will never get 
a good weld if the electrode is contaminated.

The other thing is that aluminum tends to just clog up grinding disks 
and sandpaper.  Any aluminum residue left on the disk or belt is 
probably not going to be a fine enough powder to spontaneously 
combust when it comes in contact with iron.

Not to say that it did not happen -- just that it has to be a really 
rare occurrence of exactly the right conditions.

Now I have heard first hand accounts of people machining magnesium 
and accidently igniting the chips...  Best advice there seems to be 
to keep the workplace clean as you work and if you do ignite 
magnesium to do whatever possible to get it physically out of the 
workshop as you are never going to be able to extinguish it.

Just my $0.02...
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TLCA #8536 (Digest mode)
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