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Is it normal, that a stepper motor with the following specifications can't reliably turn a plastic wheel with a diameter of 13cm and a simple direct coupling?

Type: bipolar, two phases
Voltage: 2.55V
Current: 1.7 A/Phase
Resistance: 1.5 ± 10% Ω/Phase
Inductance: 2.8 ± 20% mH/Phase
Holding Torque: 40 N.cm Min
Detent Torque: 2.2 N.cm Max
Rotor Torque: 54 g.cm²

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  • $\begingroup$ Are you using 2.55v supply or atleast 12v ? Don’t get confused by the datasheet, steppers need much higher voltage than whats written on them. You can easily give them 24v no problem. $\endgroup$ – morbo Jan 6 at 12:59
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    $\begingroup$ Welcome to Robotics, DerWaldie. What do you mean when you say, "can't reliably turn?" Stepper motors are unlike common brushed DC motors in that they need to be sequenced (stepped) correctly. If the sequencing is incorrect or, as @morbo said, the voltage is incorrect, then you could definitely have issues with the shaft (and associated equipment) not rotating correctly. Could you please edit your post to include more information about your setup? Pictures, schematics, etc. would all be very useful in trying to help you troubleshoot your issue. $\endgroup$ – Chuck Jan 6 at 13:51
  • $\begingroup$ Is this wheel unloaded, or is it, in turn, driving something (i.e., is it just in the air or is it the wheel of a cart). How fast are you trying to accelerate the wheel (or, if you're just starting up from a standing start, how fast are you trying to go, and what's the number of steps?) $\endgroup$ – TimWescott Jan 7 at 21:10
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If you try to step to fast it will fail to move. If you wish to move a large mass quickly you must accelerate the step rate gradually. Any time you accelerate to fast you should expect the stepper motor to just stop and buzz.

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Assuming the wheel is unloaded, or has a small load, it appears the wheel is not the problem in this application. Maybe I can point you to your problem in the application. It appears that you are new to the use of stepper motors. There are a few things with stepper motors that you need for proper operation:

  1. A 12 volt dedicated supply (Unless the stepper motor specifically requests otherwise)
  2. A stepper driver that can handle around 2x the current requirements for steady state (the 1.7 amp ##, you have to take into account current surges)
  3. The microstep setting (on the driver) has to be configured - in my use cases, I recommend enable full microstep
  4. The driver also needs the current configured through a resistor, a potentiometer, or through digital means.

If one of these things is not addressed, you can get unstable or no operation.

Power Supply

Just because your motor says 2.XX volts doesn't mean that is the only voltage you need. That is simply the voltage coming directly off the driver - this is not the same thing as the supply voltage.

Stepper driver choice

You are given the steady-state current for each phase. Most stepper motors are used in a 2-phase configuration, which means you should really use a driver that can supply 1.7*2=3.4 amps of current, which, to be same, should be rounded to 4 amps. This will enable enough power is available to the stepper at all RPMs.

Microstepping

If you are trying to turn a wheel, I am assuming that you want smooth motion, not necessarily fast motion. Enabling full microstepping will give you smooth motion. There should be pins you need to set to logic HIGH or little switches on the driver, depends what driver model you have (cheap vs. expensive).

Current configuring

Depending on how nice your stepper driver is, you may or may not need to configure the current on it. The nicer drivers are purchased for their specific current limits, and therefore you won't have to configure them. If you have a cheap one, like from a 3d printer driver board like the DRV8825 or those new Trinamic drivers with super hich microstepping, you will need to configure the current limits. Usually there is a potentiometer onboard that you can adjust with a non-conductive screwdriver. I have dipped my screwdrivers in nail polish for this purpose. I then start the motor up with the driver in the fully counter-clockwise position and then slowly turn clockwise until I get nice smooth motion. I suggest you use an Arduino to create a constant STEP and DIR signal such that you can then focus on tuning the current limits.

In summary, stepper motors need tuning for the desired application. You cannot just hook them up like a BLDC and expect them to work perfectly. You need to create a test setup to verify the operation of a stepper motor before adding it to your end product. They are not as replaceable as BLDC motors either: a stepper motor may look the same in size and weight, but perform very differently, keeping all other variables constant.

Try out my configuration recommendations before you attach something onto the stepper. You can use the wheel to check for the stepper resolution: the bigger steps will be more accentuated when you see a wheel doing the jerking.

Final notes

Stepper motors are designed to run hot as ****. Do not be surprised if the motor is so hot you cannot touch it, especially in applications where the the motor is always running for extended periods of time. You will need to look at the datasheet to verify stable temperatures. I have also found that, when choosing stepper motors, they do not need to have much resistance when you try to backdrive a stepper motor shaft yourself. A weak motor can have a surprising amount of torque. I was in for a shocker when I first started using steppers in belt-drive applications.

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