"NEVER, EVER GRIND STEEL AND ALUMINUM ON THE SAME MACHINE OR USE THE SAME DUST COLLECTION SYSTEM".
This also applies to wood or other handle material.
Steel filings and Aluminum filings are the two components of Thermite, and very powerful explosive.
Google Thermite and you will come up with bunches of hits.
Here we are not trying to make Thermite, we are trying NOT to make Thermite.
Several years ago I saw an article in one of my Blacksmithing Newsletters where a blacksmith had been grinding steel. Later his son came in and use his grinder to grind some aluminum. The next day the blacksmith started using his grinder again and was engulfed in a ball of flame. There were pictures of him in the article. Both hands and arms as well as his chest and face received 3rd degree burns. It is surprising how little steel filings and aluminum filings it takes to make a very violent explosion or very hot fire.
In April at the Batson Blade Symposium Dan Johnson of Steven Bader Company was talking about how they had advised a customer how to set up his dust collection system, which included directions about spark arresters, and distance from the grinder for the collection container and not to mix products. The customer took the cheap way and placed the container close to the grinder and mixed materials. The thermite exploded, leveled the concrete building and killed several workers. Wound up that it was not the cheaper way to do it.
Not only steel and aluminum should not be mixed, wood and other products also. Hot sparks from steel and wood dust can make a very mean fire and sometimes explosions.
Be careful and don't make Thermite in your shop!
Warning, Warning, Warning Explosive mixture
