On Tue, 2 Aug 2005 03:27:13 +0000 (UTC), Andrew Barss
wrote:

LRod wrote:
:Safety Tip'o'th'week: Never grind aluminum and steel or iron on the same
:machine or workstation - Thermite.
:http://www.hanford.gov/lessons/sitell/ll01/2001-36.htm

: A web search yields hardly any hits on the topic and virtually all of
: them refer to the one Australian occurance in that cite. Makes me
: wonder...

: --
: LRod

It's serious enough for Lee Valley to have written a warning about it --
was in one of their recent catalogs.

Thermite is some serious stuff -- a few ounces can burn through an engine
block, apparently.

Requires a magnesium strip or powder to ignite it- sparks off the
grinder aren't hot enough. But FWIW, I wouldn't grind aluminum
anyhow- clogs up the grinding wheels. Better to use a sander or saw
it. No doubt LV has it in the catalog as a CYA measure for the one
virtually impossible case of it happening.

I wouldn't worry awfully much about thermite, though. Even if you try
and make it intentionally, it's not all that easy to do. Iron or Iron
Oxide needs to be extremely fine, ditto for the aluminum, they need to
be mixed properly in the correct proportions, and it requires burning
magneisum or something equally hot to light it (which needs a
blowtorch to ignite in and of itself.) Miss any of these things, and
it's not going to happen. Seems more likely to me that some oil from
the outside of the metal could smolder inside the hood on the wheel-
seen that happen before and it can get pretty hot, but it's certainly
not thermite.