Stepper Motor stutters or freezes

hello forum members,
i have done searching , not quite found solution.
i using adafruit motor shield , nema 23 stepper motor, rated 1.0 amp, 8.6 volts
it 200 step motor,

i have modified wire library allow 400000 in twi.h file (was 100000).
i have nema 17 motor rated @ 12 volt , 600ma.  12 motor runs fine @ an
"rpm" of approx 400.  when use larger 8.6v motor, either fails step, locks,
or vibrates.  battery capable of supplying @ least 2 amps. 

it code - using more less standard code drive motors, based on the
adafruit library.

       if (buttons & button_up) {
               lcd.print("speed up!");
               lcd.setbacklight(on);               
                lcd.setcursor(0,1);
                lcd.print(" 400 rpm");             
                mymotor->setspeed(400);
                usemenu = false;
             }

i have similar line set speed 20 (or 80), , 8.6 v motor runs ok @ settings

any tips or suggestions help,

thanks,
ewholz

a motor shield poor choice driving stepper motor. if use proper stepper motor driver such pololu a4988 or bigeasydriver can power motors higher voltage , better performance @ higher speed. stepper driver boards allow set maximum current high voltage doesn't damage motor.

what voltages using power motors via motor shield?
it idea post wiring diagram - photo of pencil drawing fine.

...r

Arduino Forum > Using Arduino > Motors, Mechanics, and Power (Moderator: fabioc84) > Stepper Motor stutters or freezes

arduino