I ran into the guy who taught me this trick a couple of weeks ago at a swap meet. I have told him a couple of times (calling him out of the blue to thank him) how much I appreciated the education I got at his shop and I wish I would have mentioned this one.
I remember once using it at the shop on a 47 Ford truck. The set screw that holds the lock Cylinder (as I remember that's what it was holding) was locked tight and we couldn't get it out. It was inside a door that had been painted. There was a 3/8" or so hole that you stuck the tool thru (don't remember what it was, allen, screwdriver, I don't remember) to get to this set screw.
I lit the torch and quickly stuck it thru this hole in the door and heated the screw, quickly pulled the torch out and cooled the screw. Did this a couple of times all without damaging the paint on the door! LOL
I can't wait to fire up my torch to work on my truck! I love that tool.