My name is Dimitris, I'm new to this forum and relatively new to the arduino programming.
I have a project about constructing a prototype roller laminator and Ι'm doing a research for the motor to power the rollers. The requirements regarding the motor are the following:
Variable speed control of the motor [0 - 6] RPM.
Smooth motor function.
Motor torque of around 3 Nm.
After searching, I concluded that for my needs the steppers motors are the best fit since I can control the speed without a closed loop control. However for very low rotational speeds around 0.5 RPM I'am not sure if smooth motor function is feasible, so I am considering the use of gear reduction and a driver capable of microstepping.
Do you have any recommendations regarding the motor compo (stepper motor, driver, power supply)?
Yes, you need gear reduction for that speed. 3Nm is a lot of torque without a gearbox. 6RPM at 3Nm is not a lot of power, so you don't need a large motor.
Start with a small cheap motor such as a NEMA17 and a driver based on the DRV8825 or A4988 chips. That will get you started with learning about micro stepping. Power supply for these drivers should be about 12V with 1 or 2 amps current available
At first, I thought about getting a bigger motor. However the NEMA 17 with a proper gear reduction has plenty of torque. I've chosen the following motor with 51:1 gearbox which seems very reasonable.
As for the driver, I think I'll buy the Pololu DRV8825 chip as it has higher rated current compared to A4988 and has potential of 1/32 microstepping. Other than that, I can't find any other major differences between them.
However the NEMA 17 with a proper gear reduction has plenty of torque.
Are you sure?
The motor and gearbox you linked can produce only 30 kgcm of torque continuously, which is 2.94 Nm. It is almost always best to oversize parts like this.
With 51:1 gear reduction, it is unlikely that you will find microstepping useful. Microstepping is mostly used to avoid resonances at certain step rates.
jremington,
On this compo, the gearbox is the weak point as the motor can deliver a lot more torque. The gearbox can deliver continuously 3Nm with instantaneous strength of 8Nm, which provides a good safety margin as the torque requirement is by no means continuous.