I'm just getting started with Arduino and stepper motors, so I recently got a NEMA 17 from Amazon that is listed to have a holding torque of 59Ncm (Model Number: 17HS19-2004S1).
For my application of driving a worm gear, the motor keeps on skipping even if I hold it lightly with just my fingers (see attached video). I was wondering if this was an issue with my motor or if I expected too much from this motor.
For reference, I am using a 20V 3.25 Amp power supply through a TB6600 driver with 1/16 microstepping (set at 2 amps; the issue still persists even at 4 amps).
I think that is a normal video of a normal stepper motor with normal torque.
A "holding torque" is when the motor is at a full step, stationary, and then the force to get it out of that position.
Can you please post a copy of your circuit, a picture of a hand drawn circuit in jpg, png?
Hand drawn and photographed is perfectly acceptable.
Please include ALL hardware, power supplies, component names and pin labels.
The link above will show you how to post your code with a scrolling/formated window.
A stationary stepping motor provides the maximum torque.
As the speed of movement increases the torque it can produce drops. It will eventually reach a point where the internal friction and inertia of the motor stop it from moving.
So if you want more torque then slow down the speed of movement you are using.
This is not a broken motor, it is unrealistic expectations of what a stepping motor can do.
You can increase the speed by:-
supplying more current. But do not exceed the rated current of the motor or driver.
increasing the voltage of the drive, so that the current gets into the coils faster. But keep within the voltage ratings of your driver. This will require a different power supply.
59Ncm is roughly equivalent to 6kg force per cm. If the screw on your coupler creates a lever arm of about 2cm, that is about 3kgf.
So the question is, could you lift 3kg with a finger tip? I think you probably could, if briefly. So you are able to apply more torque with your finger tip than the motor is rated to produce. I really can't tell from a video what "hold it lightly" means. Your light touch may be quite different to mine
Obviously, after the gearing provided by the final gear, the torque will be higher, so applying torque to the driving shaft may not be representative. I would try the test again with the worm gear train attached. To be honest, not really sure what this finger test shows without knowing the final torque required.
