April 20, 2019 at 3:53 am #97598
I have quite a few nema 17s and drivers left over from some previous projects. Is it mechanically possible to get some extra torque by designing a gantry with provision for two motors on either side of the gantry i.e. four motors to drive the axis?April 20, 2019 at 5:42 am #97599
It seems like the two would divide the load between them. I’m not sure about more torque. I’d be concerned about them both being timed to activate at the same time. Any delay would be bad. I doubt that you would have a delay but even a micro second would cause issues. Personally I wouldn’t do it. I’d stay with one stepper motor.
I posted a similar question and found out that increasing the stepper motors size wouldn’t make a difference. Your doubling up would add more problems than it might be worth. Wiring the motors to get the signal off your board would be challenging.April 20, 2019 at 6:57 am #97609
Since the steppers are 1.2 amps each, a single 2.5 amp drive like the DRV8825 should be sufficient to drive them and any interference should delay both the motors similarly. I believe I can take care of the electronics for this setup. The thing that I am not sure about is if adding the motors will contribute towards providing extra torque to drive the gantry.April 20, 2019 at 7:08 am #97612
Extras torque, I doubt it, extra mass, yes.April 20, 2019 at 8:03 am #97624
First, as mentioned elsewhere, torque isn’t a limiting factor and the 5x nema 17 motors can handle all the 3D routing tasks you need it to.
Secondly, what will really happen is that one motor will be ahead in phase and try to do all the work, and the other motor will either pull against the first or just be pulling up slack. Each stepper will be at a different phase, up to 0.5/200 rotations off and to get that right you have to design the distance between them exactly and then be aware of which coil is which on each motor. If coil A in motor one was wired with coil B in motor 2, they would be exactly out of phase.
Thanks for the thought experiment.April 20, 2019 at 12:04 pm #97630
Again, I don’t think you’ll get torque (power), instead, you’ll get problems. As mentioned by me and another, if these go out of phase, you have the two motors working against each other. As smoothness of cut is the goal, anything that would make the router jerk around is not going to work. While you can handle the delays and matching of the electronics, why not go for a bigger stepper motor instead. I will say that Ryan answered this question for me and generally it’s not going to make any difference in the end. However, if you like to experiment, go for it. I’d use the pen instead of the router when you test. Good luck.
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