Here’s my STEPS_PER_MM section from the defaults/defaults_generic.h file:
; ;// In here we are interpreting MM as degrees of rotation
; #define STEPS_PER_DEGREE(motor_steps, micro_steps, reduction)
; ; ; ; ((motor_steps * micro_steps * reduction) / 360.0)
; #define DEFAULT_A_STEPS_PER_MM STEPS_PER_DEGREE(200., 32., 5.)
; #define DEFAULT_B_STEPS_PER_MM STEPS_PER_DEGREE((200.*(5+2./11.)), 32., 5.)
; #define DEFAULT_C_STEPS_PER_MM STEPS_PER_DEGREE((200.*(5+2./11.)), 32., 5.)
; #define DEFAULT_D_STEPS_PER_MM STEPS_PER_DEGREE((200.*(5+2./11.)), 32., 77./13.5)
; #define DEFAULT_E_STEPS_PER_MM STEPS_PER_DEGREE(200., 32, 2.)
; #define DEFAULT_F_STEPS_PER_MM STEPS_PER_DEGREE(200., 32, 2.)
; #define DEFAULT_G_STEPS_PER_MM STEPS_PER_DEGREE(200., 32, 2.)
It takes into account the gear reduction in the axis, the steps per revolution of the motor and the micro steps setting of the driver. Currently all my motor drivers are set to 32 microsteps per step.