Very small. Hardly a fire at all. Just a crumpled up paper towel smoldering in the wastebasket, probably due to a spark from grinding. Easily extinguished once I smelled it, and didn't even damage the wastebasket.
But ... what *might* have been is rather frightening! So I'm trying to think of ways to make this addictive hobby safer. Unfortunately, my only feasible location for welding right now is in a garage. I thought I had ensured sufficient clearance on all sides to avoid problems, but I was grinding in such a way that the sparks were flying rather high and far. Memo to self: don't do that again!
But in the meantime, until I get a proper shop built out back (which is definitely a *long* term goal, not a short term project), I'm wondering about building some light-weight screens that I can place around the welding/grinding area to keep sparks from going where they shouldn't. I'm thinking about making panels using 4' x 8' x 1/8" masonite in a light wood frame, and hinging two of these panels together to make an inexpensive, portable, easily configurable, easily storable screen. I envision making two of these screens (4 panels in all) so that I could channel any sparks out the open garage door.
Thoughts? Improvements? Suggestions (other than stop welding :)?