this thread is funny, but like everyone else said, safety first! I wear a hat and safety glasses even with a face shield.
I use a 3" cutoff air tool for smaller things, I mainly use 4.5" harbor freight grinders with good wheels. the hf wheels shatter and explode regularly where the good ones actually wear out over time. I also have a 7" hf grinder that I use to knock down frame welds, thick material shaping, edge bevels, etc. to save wear on the 4.5" thats usually set up with a cutting disc anyway. the only good thing about the hf grinders, the hf store is only 2 miles from my shop.