A friend of mine asked me to rebuild his wheel, but he had unlaced and removed the spokes before removing the lockring and cog.
Because it was proving difficult to get a chain whip and lockring wrench on the same side, I put one of my cogs on the "flop" side and secured it with a chain whip, then used the lockring wrench on the other side. Hilarity ensued.
Hubs aren't made to take that kind of torsion...
...especially when you are using the lever of the Gods, in this case the tube from a Park repair stand. That's like 3 feet of leverage. The vise-grips are holding the wrench on the lockring, which is definitely handy. I swore to myself one way or another that lockring is coming off. It's still there.
I really thought the chain whip would have broken first.
The worst part? Now MY cog is stuck on the other side, thanks to like 300 ft-lbs of torque. Next step? I'm nailing the remains of the hub through the holes in the flange to a large board and removing my lockring.
In other news, a Hazon lockring tool is pretty strong. And use vice-grips to secure the lockring tool to the cog...definitely helped.