Bearing-reinforced Stepper Tackles Hefty Axial Loads

Bearing-reinforced Stepper Tackles Hefty Axial Loads

  12 Aug 2019

These days, it’s common among us hackers to load a stepper motor with forces in-line with their shaft–especially when we couple them to leadscrews or worm gears. Unfortunately, steppers aren’t really intended for this sort of loading, and doing so with high forces can destroy the motor. Fear not, though. If you find yourself in this situation, [Voind Robot] has the solution for you with a dead-simple-yet-dead-effective upgrade to get your steppers tackling axial loads without issue.
In [Voind Robot’s] case, they started with a worm-gear-drive on a robot arm. In their circumstances, moving the arm could put tremendous axial loads onto the stepper shaft through the worm–as much as 30 Newtons. Such loads could easily destroy the internal stepper motor bearings in a short time, so they opted for some double-sided reinforcement. To alleviate the problem, the introduced two thrust bearings, one on either side of the shaft. These thrust bearings do the work of redirecting the force off the shaft and directly onto the motor casing, a much more rigid place to apply such loads.

This trick is dead simple, and it’s actually over five years old. Nevertheless, it’s still incredibly relevant today for any 3D printer builder who’s considering coupling a leadscrew to a stepper motor for their Z-axis. There, a single thrust bearing could take out any axial play and lead to an overall rigid build. We love simple machine-design nuggets of wisdom like these. If you’re looking for more printer-design tricks, look no further than [Moritz’s] Workhorse Printer article.