Originally Posted by Bobby_M
The trick with this operation, I think, is patience. I first tried cutting all the way through and then going around cutting on the edge of the metal. It turned out that light pressure on top, just grinding through worked best. A flat disc doesn't like making turns but the very edge will.
It's funny, I also have a pneumatic grinder but didn't even think to give it a try.
Yeah, your first pass around the keg should basically be scoring a line. Once you go around once, the disc wants to stay in that groove, just take it easy and you'll be through in three or four passes. No need to rush, let the tool do the work and it's an easy job.