I am not very experienced with chisels, so I just shape mine completely free hand on the 6x48 belt sander. Since that has no speed control, the shaping of the round/oval and the ridge in the right place from a square piece can be a bit of an adventure. Throwing away a piece because I did not get the right shape before it got too thin, getting it ripped out of my fingers and shot across the room, and sanding my finger tips are common occurrences, so I am not sure you should listen to me on this
Stefan