Use a big bar on the crank arm, it never fails. Just make sure you're turning it the right way! Follow the wiki, I made it so I know it works. I've done about 5/6 freewheels now I think? It's the only way that doesn't damaging or destroying them. That I've tried anyway. A tip I got from Inur, try soaking it in WD40 over night, just leave a pool on top of the freewheel so it will run run down the threads as best it can, this can help to free it off. Best of luck!