- Jan 26, 2022
- Reaction score
I use this type coupler on all three axis on my CNC Mill, and have never had a failure. But, the Z axis on my lathe uses a Nema 34 stepper with 1100 oz-inch of torque, while the mill uses Nema 23 steppers with just 291 oz-inch.
According to Lovejoy, this style coupler is only intended for use where alignment is within 0.5 degrees or better. In situations where the builder has decided they look sort of like universal joints and then tried to use them as such they will fail quickly. With any significant misalignment they will tend to bind unless space is left between the spider and the jaws, not a recommended practice.couplers like that are designed to accommodate any misalignment between the shafts, perhaps the reason the rubber deteriorated is that it was being continuously flexed by misalignment, perhaps the epoxy replacement will shift the deterioration to a more expensive to repair part (either the lead screw and nut or the stepper motor itself) (and, no, epoxy does not flex like rubber). perhaps you should have filled the coupler with silicone rubber or shoe-goo or ...
One of the things I learned during a 6-month posting to Metalastic in Leicester was that rubber should always be used in compression.
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