markmokris:
You asked "Does it miss steps?" It misses microsteps. I think for every 8 microsteps, it hit-or-misses several. But by the end of 8 microsteps, it has caught up, having produced the equivalent of an accurate full step.
Does that mean that it will accurately perform a full revolution?
I am using an 18V variable 3A bench supply. I started at 12V (which the motor is), but have gone higher. The bench supply has a current meter.
Can you go to 24v to see if that improves things? (Assuming that is OK with the Easydriver).
The meter on the power supply is not relevant because it is measuring the current at 18v and because it is not measuring the minute changes of current going into the stepper coils
also have a 2A bipolar stepper motor and a Big Easy Stepper Driver.
Whatever the datasheet says 2A is too much for an A4988 unless you have a big heat sink and a cooling fan. 1.3 or 1.4 amps is more realistic. I believe drivers using the TB6560 chip can manage up to 3amps so should be comfortable at 2A.
I don't have enough personal experience of microstepping to know if your problem is common or not.
...R