The final torque at the driven object (gantry or whatever) must take more than the gear/pulley ratio into consideration, what about the lead/pitch of the screw? (you could probably wag it by mutilplying x 4 for a 4 to 1 as an estimate for just the gear/pulley part).
You will give up speed for torque using pulleys/gears but can gain some back by using a drive screw with fewer turns (larger lead/pitch) but then that will bring the final torque back down..................... |