The culprit.


120910_0389 by racer_46_x, on Flickr
I use this wheel to remove paint, rust and mill scale. It works great but wears out quickly and is a little expensive at $5 ea.


120910_0387 by racer_46_x, on Flickr


120910_0388 by racer_46_x, on Flickr
The results. It could have been much worse.