Recently as a challenge to myself I have been building a eye mechanism for a very small animatronic.
There is not much space in the head and because each eye needs 4 motors, therefore I decided to go with very small linear steppers (10mm stroke). I have connected them all to the arduino using a CNC shield and some A4988 drivers. The motors work fine when connecting them individually to the CNC shield. But as soon as I connect both, Just one rotates (if i disconnect the one rotating the other one rotates) It almost seems like one motor is impeding the movement of the other one, i have checked and switched the A, B coils but that has not had any effect. Any Ideas what could be happening?
(Each motor is connected to its own A4988 driver)
(The Shield motor voltage is being supplied by the arduino 5v pin, since the motors are tiny)