Join Date: Sep 2006
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If you have access to the rounded bolt heads, get your goggles out and butcher the nuts off with a grinder. A grinder will tackle anything. Wear your ear defenders too. Watch your fire risk if you have gasoline around. You really must wear eye protection.
The keyway lock screw should drill out, given some care with it. If you tear up the female thread, you can always re-tap with a larger thread once you get the coupling off the shaft.
Last resort is to take the grinder to the shaft as well, and cut it off aft of the coupling. Leave enough "stub" so that you can work with it a little. A hydraulic press will get the coupling oiff the shaft stub.
If the couplingis more valuable than the shaft, you can always grind the coupling off and save the shaft. It is not as easy, but it can be done.
With luck though, you may well get it off. Use lotsa WD40 also, where possible.