Before posting this question I've been looking up google but can't find an answer to this question other than "speed control and torque control". I've done a lot of research on steppers but still don't know the relation of torque and speed. Don't get me wrong, I don't mean the relation of "increasing the speed too much, decreasing torque.". I am wondering if the speed will be constant when loaded in a bipolar setting.

For example, the stepper turns 130 rotations per minute. The stepper has a max torque output of 1Nm. When I load the stepper with 0,5Nm, does it decrease the speed? Since a stepper motor has to do certain steps, I think the speed would stay constant. I want to know if the speed will be constant or a feedback & PID control is required.

Thank you in advance!

  • \$\begingroup\$ I have explained how they work best in this forum Use search at top . Cogging or slipping depends on acceleration, current limit and load exceeding cyclic torque , gear ratio if needed. Speed only depends on step rate of commutation but max speed depends on all the above \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jun 5 '18 at 6:44
  • \$\begingroup\$ GRBL Panel for windows with Arduino +CNC Shield in kits give maximum 2D or 3D precision, speed and torque with adjustable everything. Some servo physics understanding and learn how to use G code is necessary but awesome. electronics.stackexchange.com/… \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jun 5 '18 at 16:44
  • \$\begingroup\$ Thanks for the tip. I'll be planning to make a 3D printer next year so this would come in handy. \$\endgroup\$ – Capt. Frost Jun 6 '18 at 10:39

A stepper motor, as the name says, moves in steps. Each step is a fixed angular movement and the number of steps per second defines the speed. It will always move at the same speed no matter what load you put on it until the load is so big that it simply can't move. At that stage it will starts to skip steps or outright stop if the load remains too high. You will hear a clicking noise when that happens.

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  • \$\begingroup\$ I have witnessed the step skipping and indeed, hear the clicking noise. Thank you for your answer! \$\endgroup\$ – Capt. Frost Jun 5 '18 at 8:32
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    \$\begingroup\$ "load is so big it can't move" is correct but loosely defined. "can't accelerate fast enough to keep up with the steps" is a bit better : a good stepper controller can ramp up and down the step rate slowly to accelerate a heavy load. \$\endgroup\$ – Brian Drummond Jun 5 '18 at 8:57
  • \$\begingroup\$ It is loosely define because too many things play into it. Acceleration is just one factor. Note that you can even loose steps just holding position. \$\endgroup\$ – Goswin von Brederlow Jun 5 '18 at 9:13

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