Which power supply are you using? Is it capable of continuous 1.5 Amps?
I am using a 3S LiPo battery which can supply over 50A if needed.
Be VERY CAREFUL never to connect or disconnect the wires between the motor and the stepper driver while the driver is powered up. The driver will be instantly destroyed.
How is your multimeter connected?
What current do you measure when the potentiometer is turned to the other extreme?
What motor power supply are you using (volts and amps) ?
I have my wiring set up on a breadboard with three wires for the motor connected directly to the motor and the fourth that connects to a header pin on the breadboard which I connect to another header pin via the multimeter using the amp measurement setting. The second header pin then is wired to the motor. I do not have any additional multimeter clips so I am just very careful to keep the leads pressed to the headers so that I do not disconnect the wires while running so as not to ruin my motor or driver as you stated.
When the potentiometer is turned to the other extreme it reads 0A.
Motor power supply is 3S LiPo which reads about 12.5V and can supply up to around 50A continuous current.
Not necessary, power supply current draw is less than the motor current draw with a stepper driver.
The A4988 has an absolute maximum rating of 2A, so you'd never expect it to handle 2A, and in
practice the small modules struggle over 1A due to limited heatsinking.
The initial state at power on is at 45 electrical degrees, so that each winding should see 1/√2 times the
nominal set current at that time. So if set for 1A, you'd see 0.7A or so in each winding.
(Remember to never connect, disconnect or reconnect the motor windings with the power applied -
this usually destroys the device. This means that when measuring current you can't do handheld
multimeter measurements, you have to set up with the multimeter connected solidly into the circuit
Right, so I turn my potentiometer all the way up and only get a reading of ~0.7A. Shouldn't that be 1.4A? The plan is to limit the driver to the motor's rated amps of 1.5A and use a cooling fan to cool the driver. However, I am measuring only 0.7A max, which would be 1A normally instead of 1.4A which would be 2A normally. Or am I misunderstanding how it works?
Additionally, the motor runs fine with the set up. I used the same wiring as described above with the multimeter hooked up and ran the motor through several different revolutions. While the amp measurement fluctuated as expected I did not see it go above the 0.7A as previously measured.