That makes sense. In a circular fashion I was trying to say that with an 18tpi mechanical advantage you've got 18*42" or 756 turns to your lead screw and at 240rpm it's going to take you over three minutes to move one end to the other. A 5tpi screw and 240rpm will still take almost a minute with accelerations.
On the other hand, I'd do the sums and work out the minimum force required by your machine, what gearing (tpi) your motors will stand, and see where you are for speed and torque curve. It's an interesting balancing act and more rpm, especially in bipolar parallel makes life easier. |