When you grind a bunch of aluminum (chainsaw case) on you disk sander, clear out the aluminum powder periodically. Once you have a big pile, then you grind some steel, you get a big fire! The sparks light off the aluminum powder. This happened to me a couple of days ago. Made burn marks on my bench and floor. It was a very significant white hot fire. Trying to scoot the burning pile off the bench with a handy stick made a big woosh. There was not serious threat of buring the house down but, it gave me quite a fright.

Intelectually I know all about aluminum powder and fireworks. I just did not engage my brain on this issue.

Keep it clean,