markmokris:
I know I am in microstepping (1/8 step) mode, the default, because when I send EXACTLY 1600 steps, I observe EXACTLY one complete revolution.
Good to have that confirmed clearly.
However, when I increase the delay between steps to "delay(500)", I observe much inaccuracy from microstep to microstep. Sometimes, at some microsteps, the motor doesn't move at all. Other steps, it moves more. It seems like, at some at some microsteps, it is "catching up".
When it is working like that will it make a full revolution accurately or does it miss steps?
Microstepping is achieved by making the motor coils work against each other so it is never going to be as precise as full steps.
Have you the current limit on the Easydriver correctly set for 400 mA to match the motor's specification?
What voltage is your motor power supply? Stepper motors generally work better with higher voltages - within the range acceptable to the motor driver.
...R