I've been looking for stepper motors which are less expensive than the ones sold by Ultimachine and Lulzbot. So, I ordered some from China. I wanted to compare them with the steppers I got from Ultimachine, so I set up a testing rig:
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| Simple Rube Goldberg Machine? |
Boring details:
- The green pulley has a 1 inch radius.
- In each of the tests, the motors are attached to the same stepper driver. This makes sure there is the same amount of current going to the motors in each of the tests.
- I tried each test a few times, to make sure the results were consistent.
- The motor is held to the table by a clamp.
- I drilled a hole through the pulley, put the string through it, tied a knot, and wound the string around the pulley a few times. There is a nut on one end to hold it to the fish scale.
- On the "moving torque" test, the fish scale was clamped down above the edge of the pulley and the motor pulled against it.
- On the "holding torque" test, I just pulled the fish scale up until the motor skipped steps.
- Also, I recorded all the results from the scale with video and took a screenshot of the moment it hit maximum torque in each instance.
Chinese Motor Results (17hs8401):
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| Moving Torque: 12 oz-in |
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| Holding Torque: 20 oz-in |
Kysan Motor Results (Ultimachine):
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| Moving Torque: 16 oz-in |
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| Holding Torque - 16 oz-in |
The Kysan motor has been on my printer for several months and it works well. It seems to have a stronger moving torque than the Chinese stepper when the same amount of current is applied.
Conclusion: Since I'm operating the motors at a 1/4th of their rated torque, it's no surprise that both motors work fine. To me this proves the Chinese motors aren't so crappy that they fail when operating at only 1/4th of their rated torque.
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