i am trying to build a small arduino powered forkilft that is tasked with carrying a small box weighing 100 pounds from on cnc to the other. all it has to do is pick up the box. after scouring the internet for several hours, i cannot find any decent info on how to size the stepper motor for the lifter. it is about 3 feet high, does not have to be very fast at all, just has to be able to reliably and steadily lift 100 pounds. their is no load on the motor, it is going to be a single pulley configuration. sorry for the bad diagram, it should give you just an idea of the way it will be set up. accuracy is within an inch or so, nothing to worry about really, an probably if it took about 30 secs of less to go three feet so about 1 inch per sec. so the question is, how big of a motor do i need?
To raise 50 kg up 1 meter in 30 seconds takes about 17 Watts, so plan on a motor driver and motor capable of at least 40 Watts output.
Steppers are extremely inefficient, and you have given no reason to use one.