I had to remove my coupling and also had difficulty. Heated the coupling under tension from a puller. Heated the coupling to 300-350 degrees F. This is well below any temperature that is going to change material properties. Tensioned the puller (or use a socket as suggested), heated, and gave a good rap with a 3# hammer using an aluminum block on the rear of the coupling so as to not damage the coupling. Second try and it popped off.
If you do have to cut the coupling, I would consider cutting in-line with the shaft (carefully and do not go into the shaft). Probably don't even need to cut down to the shaft - just almost. Use a cold chisel with the back side of the shaft supported on a metal block. You should be able to save the shaft this way
If you do have to cut the coupling, I would consider cutting in-line with the shaft (carefully and do not go into the shaft). Probably don't even need to cut down to the shaft - just almost. Use a cold chisel with the back side of the shaft supported on a metal block. You should be able to save the shaft this way