I wanted to use the NEMA 17 stepper to drive a blade/flapper that I have custom made for some physical application.As soon as I tighten the screw,the motor stops rotation in the usual way. Don't have any idea the reason for this. Note: 1.The blade/flapper is not too heavy and the torque rating of the Motor is sufficient. 2. Doesn't spin even if I help with hand 3.It does a very slight movement almost at the same place. 4. Problem occurs as soon as I turn the screw to fix the blade on the shaft. 5. I've tried with using glue into the joint,the problem seems to be lessened but still present,also using the glue method wouldn't be suitable for my function as I need more rigid join.
I will take a wild guess - your accellerating to fast for the mass of the blade / power of the stepper motor.
You can check this by trying to step much slower - perhaps 1 step per second for testing