Spent a bit of time today to see if I could narrow down the problem. When using the A4988 driver there is very little torque from the steppers and they are easily stopped. I rigged up a couple of L298N drivers and ran a simple sketch and it is like night and day as impossible to stop the stepper. Should there be any reason the torque is so low with the A4988? They work but could they be faulty? I have been very careful today to ensure all power is removed before making adjustment.
I have adjusted the A4988 but saw very little if any difference. Was using a 12volt psu and just now changed it to another unit giving out 30 volt but no difference as the steppers move but soon stop with various tones being given just like they are overloaded.
The fault only appears on the Y axis where I have two steppers and have made A a slave of Y.
Any help much appreciated.