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I would like to take a powerful stepper motor, and sometimes weaken it, so it will stall when it hits resistance.

I understand that I can reduce torque with microstepping, but it does not seem to be precise enough. Is there another way to make the motor less powerful?

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    \$\begingroup\$ use less current; torque is proportional to the current through the coils. \$\endgroup\$
    – esoterik
    Commented Jun 26, 2018 at 0:13
  • \$\begingroup\$ Microstepping modulates the torque available and is highly non-linear. Reducing the current is mostly linear though you need enough torque to overcome inertia. \$\endgroup\$ Commented Jun 26, 2018 at 1:10
  • \$\begingroup\$ A decent stepper driver has a current limit pot, so you can choose to limit acceleration to avoid step skipping then reduce the current limit just above this threshold. Otherwise reducing V+ can achieve simular results. \$\endgroup\$ Commented Jul 11, 2020 at 19:22

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Current is controlled by Vdd , simply reduce till it slips but your acceleration must be low.

Because if you don’t know inertia reactions, the force can be exceeded with no load. There is an advantage here to use microstepping , because the voltage is more sinusoidal per pole and thus lower torque and greater sensitivity.

Make the inertial force less than the impact. Then by acceleration and max velocity, minimum impact is achieved but then you lose position tracking.

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  • \$\begingroup\$ Losing position tracking might not be a bad thing. Torque-to-home, for example, would exactly fit the original description of "sometimes weaken it" in my interpretation. \$\endgroup\$
    – AaronD
    Commented Jun 26, 2018 at 3:24
  • \$\begingroup\$ Bad idea . Put in home switches , go max current , max acceleration and speed . Mine does 1000 mm/s with 0.1mm accuracy over 1.2m XY \$\endgroup\$ Commented Jun 26, 2018 at 3:57
  • \$\begingroup\$ Yes, that would be better, but I've had a number of projects that were mechanically finished before the controls department even knew about them. And no, we couldn't change anything. Thus, TTH. \$\endgroup\$
    – AaronD
    Commented Jun 26, 2018 at 4:19
  • \$\begingroup\$ Better to define specs up front next time \$\endgroup\$ Commented Jun 26, 2018 at 14:11
  • \$\begingroup\$ You know that, and I know that, but with a dysfunctional company (don't work there anymore), or the occasional customer who's really good at that one discipline and gives you an unchangeable assembly...well, you know how it goes. \$\endgroup\$
    – AaronD
    Commented Jun 26, 2018 at 16:48

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