I haven't tried the hammer and punch method of removing a threadless or de-threaded crank. I can tell you that the gear puller would be just the ticket as it works exactly like the proper tool, if you still had the threads. The gear puller will grab the crank from behind with its pivoting arms and bear down on the spindle (axle) tip as you turn. My local auto parts store sells these things for much less than you would think they would cost. This is the benefit of employing slave labor from Asia to manufacture just about everything. If the guilt and regret that this wage race to the bottom, doesn't bother you too much, than for less than 10 bucks you will have freed your crank. (Increasingly there is no choice anyway, so enjoy.)
Garth Libre in Miami Fl.