Consider how hard you would have to push a hand held router-it isn't that hard at a moderate rate.The bigger hand held machines will be about 2.2kW.It then becomes a matter of calculating the best way to turn the energy of the stepper into a force to accomplish that and you have a choice between leadscrews or belts.Long leadscrews may whip at speed or you can fix the leadscrew and find a way to rotate the ballnut,in either case you can generate sufficient force with a NEMA 23 of reasonable size.As indeed you can with a rack and pinion.There are people on this forum who know far more about inductance than I ever will and who may guide you in the best direction and that direction may be away from NEMA 34's.