# How to couple a motor to a screw drive?

I have a simple linear translation stage that is driven by a screw, and I would like to attach a stepper motor to the screw drive. The axis of the screw and the axis of the motor are approximately colinear. The issue is that, as the screw turns it recedes away from (or advances towards) the motor. The spacing between the motor shaft and the screw drive can change by as much as 10 mm. A diagram of the problem and an example of the type of stage are shown below.

How can I couple the stepper motor to the screw drive in a way that allows for this expansion/contraction of the space between the two?

• Can you put together a diagram for this? I'm having trouble picturing where all your inputs and outputs and connections need to be. Oct 28 '15 at 20:06
• I guess my main question is if the stepper is connected to the screw on its axis or if the connection is in the radial direction. Oct 28 '15 at 20:19
• I would guess that, if the screw moves away from the motor, you've got the motor installed in the wrong location. You want the motor on the drive end, not the actuated end. Oct 28 '15 at 20:26
• @ChrisMueller can't you turn it around so the screw remains stationary? Oct 28 '15 at 20:49
• Have you considered a splined coupling? You could get 10mm of extension/axial movement from a spline. Are you concerned at all with backlash? Oct 29 '15 at 3:46