Stepper Motor Shared Load Problem

[becsocal]

I am new to this forum and am looking for some help on a application problem I am having with stepper motors.

I am testing a system that was originally design for one load. Eventually, the system was used in another application with a larger load... however due to space limitations a larger motor could not be used so a second motor was installed and a linkage between the two motors was created. There is no feedback with the stepper motors. Essentially, I know that the stepper motors will never "share" the load equally but am struggling to explain it clearly or propose reasons why this is the case regardless of how accurately you align the motors and lead screw nuts at installation. Over time since the loads are not shared and there is no feedback one motor will take more load. I've attached a powerpoint sketch of what I am describing. Any help or information would be appreciated.

Thanks!

 

[MikeHalloran]

If the motors share a common driver circuit, or, better, identical driver circuits sharing clock and control signals, and if they are strong enough to not lose steps, and if they are mechanically phased the same with the power off, there is no mechanism by which they would 'drift' differentially.

... but I would feel better if the stepper shafts were also linked to each other by a train of spur gears.
... in addition to the uncertain synchronization provided by the pair of worm gear sets and the shared beam.







Mike Halloran
Pembroke Pines, FL, USA