Linear Stepper Motor Leadscrew Runout
Linear Stepper Motor Leadscrew Runout
(OP)
Hi all,
New to forum, have a problem I've come across at work. We have a linear stepper motor with a single side mount lead screw. When the motor turns the free end of the leadscrew is wiggling about 1/16". What could be causing this? The manufacturer is saying that extra play between the nut and leadscrew (to allow for some misalignment) is causing the runout and is normal. I'm not sure this makes sense, and I have my own ideas, but I wanted to see what other people think. See linked videos of wiggly leadscrew.
https://www.youtube.com/watch?v=VYdykmyADYw
https://www.youtube.com/watch?v=6PCl1UuBU78
Thanks!
New to forum, have a problem I've come across at work. We have a linear stepper motor with a single side mount lead screw. When the motor turns the free end of the leadscrew is wiggling about 1/16". What could be causing this? The manufacturer is saying that extra play between the nut and leadscrew (to allow for some misalignment) is causing the runout and is normal. I'm not sure this makes sense, and I have my own ideas, but I wanted to see what other people think. See linked videos of wiggly leadscrew.
https://www.youtube.com/watch?v=VYdykmyADYw
https://www.youtube.com/watch?v=6PCl1UuBU78
Thanks!





RE: Linear Stepper Motor Leadscrew Runout
RE: Linear Stepper Motor Leadscrew Runout
the adjustments on the acme nuts of machine tools are typically used to eliminate backlash by allowing the axial preload on the thread to be adjusted.
The design issue really come from the fact that you have 3 constraining points on your threaded shaft (2 bearings in the motor and the acme nut). the amount of radial clearance in the came nut is limited so it might be a good idea for the design to allow for some degree of misalignment (although in my opinion from the scale of the device i can see in your video the runout does seem excessive). this can be accomplished in several ways one is by allowing the acme nut to float within a plane and constraining it in rotation and axial directions only. it is also common when mounting a motor to a shaft to use a flexible coupling for similar reasons.
RE: Linear Stepper Motor Leadscrew Runout
Even when allowing the motor to float (unbolted it and held it by hand) there was side loading on the motor from the nut-shaft interface. This tells me that there isn't radial clearance, but radial interference... I'm waiting on a report from the manufacturer on their investigation. We're suspecting that the nut was just manufactured eccentric to the bearings, as we haven't had these issues with different manufacturers' motors in the same setup.
RE: Linear Stepper Motor Leadscrew Runout