Anyone experienced in adjusting stepper motor torque via current? I guess any variable current power supply would be useful for that matter. I am looking at implementing a PID control that takes a pressure reading and adjusts torque accordingly. Any ideas/pointers greatly appreciated.
if i’m not mistaken its the stepper driver that takes care of regulating current sent to the motor, and most of them have an adjustment built in. Mine has jumper switches but many have a small pot that you can turn with a screwdriver (i think the bigeasy driver does). Maybe if you swap this potentiometer with a digital one you can control it and you’d be able to set the current/torque on the fly ?
the plans for the adafruit drivers are available online i believe so you could build one from components if its too tricky to hack one to bits
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There’s lots of ways to do it. What are you trying to achieve?
Can be done with pwm or with ballast
Nice one. Yes, there are current pots on at least two boards I have worked with, one being the white pots on the GRBL board (same as on the Shapeoko in the space):
I’ll look into substituting them for digital pots.
I’m working on an extruder that uses flakes instead of pellets so working on the assumption that if it easier to push the molten plastic through the barrel it is less compact and needs some extra humpf.
So slow running and no need for a high holding torc .
Simple and ignorant will do what you want with whole stepping .you could lose the 6v supply at the expense of efficiency and a bit experimenting will be required to figure out how far you can push the motor before it saturates.
You could do a lot better with pwm , or maybe consider using a dc motor and a gearbox
I think that what he needs is to be able to set the run and holding current separately. And possibly over drive the motor at the beginning of the step .
All desktop extruders I have seen so far, commercial and diy, use dc motors with gear reduction, now that you mention.
That went straight over my head so will ask next time I meet you at the space.
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I think that a dc is a better fit for this application as it’s simple and it intrinsically dose the maths for you so no coding is required
Plus the world is awash with old battery drills with dead batteries and that way you get a gearbox , safety cluch and pwm controler for free
Driving stepper motors with square waves is fine for simple stuff but if you get clever you can squeeze a lot more juice out of them .
Feel free to ask me next time you see me 