I have tried to control a farily small roller blind with about 1M width and 1.1M drop using 28byj48 5V motor in unipolar mode and whilst it would travel downwards, there was not enough torque to get it to go back up, even at slow speed. The blind is mounted on a 3D printed bracket which includes metal roller bearings to reduce friction.
So I got some 12V 28byj48's and converted ithem to bipolar by cutting the track and still have the same problem.
I am using the stepper library, a TB6612FNG driver board and all powered from a 12V 12Ah lead acid battery (which should easily supply the required currentl).
So my question is, can I do anything to get more torque out of this motor or should I consider another? IF another motor is better does anyone have any suggestions as to what might be best? i am considering the nema17 (hanpose 17H4401S) as I already have one, but if it is not suitable then I don't want to waste a lot of time re-designing and re-printing the fixings.
First determine/calculate/measure the required torque.
Then choose the motor (and gearing) needed to provide this at the speed you need.
For stepper's ignore the holding torque, the dynamic torque rating is much lower and
is what matters for movement - a good datasheet will show graph(s) against speed
for a stepper's torque.
No, increasing the torque of a motor itself isn't a thing. Reduction gearing is how
you increase torque (by trading it for speed).
Motor volume is strongly related to torque (ignoring gears). If you want lots of torque in
a small motor you will need gearing.
@MarkT@braskas -
Thank you for your advice. I will go away and research how I can measure or calculate the required torque (one blind will be >4m2 so will need something a lot 'heftier' than the smaller ones. But at lesast the big one can take power from the mains, so that takes one problem out of the build!
braskas:
First max out the current for your stepper. Some drivers have a potmeter to adjust this.
If that is now enough try gearing or simply a larger and more capable stepper motor.
No, don't do this, set the current correctly for the stepper - over current in a stepper will
cook it, possibly demagnetize the core, and could start a fire.