Can be adjusted manually with Vref, or digitally (for marlin in Configuration_adv.h.
Imax -> Maximum current per phase. This is often the value on the motor datasheets.
Irms -> Root mean square current, or average current.
Vref -> Voltage of the reference pin (or contact) on the stepper driver. If setting current digitally, this is not important.
| Imax = Irms/√2 |
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This can be estimated with
| Irms * 1.41 |
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If adjusting manually, remember that Vref is a value from 0..2.5V and the maximum settable motor current is 1.77A.* Therefore:
| Vref = (Irms * 2.5V)/1.77A = Irms * 1.41 |
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| Vref = Imax |
*Note that TMC2130 and similar should not be used above 1.2A, even if they can be set higher.
Before setting the RMS current just calculated, it's usually better to set around 60-80% of that. If there are skipped steps, you can increase the current. If the motors get too hot, decrease the current.
The stepper motors should not be getting any hotter than 50-60°C. While they may be capable of operating at higher temperatures, the plastic parts on your printer may not. This is especially important when your motor mounts are 3s printed.