Originally Posted by Lucky-Charms
Have you personally (or know/seen) anyone who's done this? It seems that with the steel (cog) and alum. (threads on hub) the alum. hub would expand faster than the steel cog, making it even harder to take off. Of course I don't have any real experience with any of this beyond idle speculation.
I have not personally tried this method on a cog, but It worked for me to get an old BB off a POS frame. When I used to work in a sketchy LBS, we also used this method to get parts off of old junker frames. Not specifically on cogs, but seatposts, bbs, etc.
I think that the alu will expand faster, but the expansion/cooling of the cog/threads may break the "seal"...