So I have a quest to remove a BB from a bike so I can replace the front derailer.(yeah, its a lower end kids size Giant). It's clear this bike has had a hard life, what ever can rust, has. The front derailer is frozen solid. The drive side BB cup it also pretty solid. Using a BB too, bolted to the axel, a long wrench, and wacking it hammer, didn't budge it. So I had the idea to put my 600ft\lb DeWalt impact driver on it to see if I can get it off. I know it's a cheap bike, and probably not worth the effort to get it off to replace it, but it's the principle and I DO NOT WANT TO BE DEFEATED! by this thing.

Has any body done this, and what was the result?

Like I said, it's a quest.