Building my first MPCNC with a Ramps 1.4 board with A4988 drivers. I am using a 12V 6A power supply and have successfully got the machine to move and home itself to the correct front left home position. My issue is that the stepper motors have a very high pitch wine/noise, mainly noticed when machine is at rest and motors are in hold state, and the motor drivers seem to get abnormally hot (almost too hot to touch).
For reference, the stepper motors were provided in the kit from Ryan (STEPPERONLINE 5PCS Nema 17 Stepper Motor Bipolar 2A 84oz.in 48mm 4-Lead for 3D Printer/CNC) and these have a 2A rated current. To find the Vref for the drivers i used the formula Vref = 2A * 8 * 0.068= 1.08V. This is what my drivers are set to.
Does anyone know why the motors are making this whining noise and why the drivers are so hot?