Hi!
First and foremost i'm a huge beginner when it comes to electronics and have a little experience with arduino.. Therefore i'm sorry if i'm very vague and clueless. Please be easy on me. 
For my project i am using an arduino uno, can be changed if necessary. I want to control 6 nema17 stepper motors (12v, 0.4amps, 26ncm) individually using a a4988 driver for each of them. They will be used to pull strings, not a steady weight but pulling an elastic fabric with the weight ~ 1kg, by a wheel (2cm radius) attached to the motors shaft, so it should be 2kg.
Right now i want to test one motor using the attached diagram. To do that i need to adjust the current limit of the a4988. I tried following pololu's tutorial on setting the current limit using the formula VREF=8⋅IMAX⋅RCS that i got from pololus website. Depending on the driver model Rcs will be 68 mΩ or 50 mΩ but my a4988 isnt from pololu so i just used 68 mΩ for testing first, resulting in Vref= 80.468 = 217.6 mV. (i couldnt find details on the Rcs on mine, what should i do? but i also saw another formula IMAX = VREF x 2.5 so it'd be 0.4/2.5 = 0.16V) When i tried setting the current limit with the potentiometer onboard, i only got a range from ~ 3.07 - 4.30 V. I can't go any lower, what am i doing wrong here?
Also i found this 12 VDC 5 A adapter, will it be enough for this? I believe i should connect the motors in parallel, so the voltage will 12V for all and amps will be added, so 0.4 A *6 = 2.4 A. Then 5 A should be sufficient, right? I want to plug it in directly to the arduino but i saw that some had problems with 12V. I believe it was because they were unregulated power sources, so as long as its regulated it should be fine, right? How can i know whether mine is regulated or not? Furthermore i read that to maximize the stepper motors performance a higher voltage would be better. Would it be wiser to use more than 12V and connect it externally with a dc barrel jack adapter?
I'd be greatful for any help 
a4988 longruner
nema17 longruner
