Stepper motor strain with acme

[andy_ck87028]

Hi all,

I have been concerned about the strain imposed on the bearings of a stepper motor when directly coupled to an acme thread. Some of the strain would be taken up by the acme support bearings but is that enough?

I was thinking that the acme shaft at one end could have an end stop butted up to it with the shaft turned to a point to minimise friction but what about the other end?

I am planning to have a proper coupling to join the acme to the motor which means all residual (one way) strain would be imposed on the motor.

Then I realised that some motors are double shafted.

Would it make sense to have a bush placed on the other end of the stepper motor and have that bush butted up against an end stop as well.

So, the visual sequence would be stop, bush, motor, coupling, bearing, thread, bearing, point, stop.

Does that make sense?

Andy

[jeffs555]

The screw should be fully supported by its bearings. These bearings should be designed to handle all of the thrust and radial loading, so that none of the thrust or radial loading of the screw is transmitted to the motor. Generally, you have two preloaded bearings on the motor end of the screw to take up the thrust loads, and one or two radial bearings on the other end. The preloaded bearings would generally be angular contact bearings which are designed to handle both thrust and radial loads. Many people use deep groove radial bearings in place of the angular contact bearings. They are not really designed for thrust loading, but are much cheaper, and seem to be ok for low volume home use.

[Torsten]

Originally Posted by andy_ck87028 Then I realised that some motors are double shafted. Would it make sense to have a bush placed on the other end of the stepper motor and have that bush butted up against an end stop as well. So, the visual sequence would be stop, bush, motor, coupling, bearing, thread, bearing, point, stop. Does that make sense? Andy

This would work, the connection from motor to Leadscrew will have to
be solid, no flexible couplers inbetween.
Requires to have a perfect anglinement of motor and Leadscrew.
Another drawback would be temperature growth of the combo, the distance
covered would be longer then usual and exibit more fluctuation wich has to
be allowed for.