For a project, I have two steppers connected to each other by a wire and I require the stepper to rotate in opposite directions, wrapping the wire around them, decreasing its length, or releasing previously wrapped parts of the wire, increasing its length. The steppers required are very small and I have therefore decided to use the stepper motors inside the CD Drives of old laptops. However, steppers only hold their position when there is a current passing through. This drains the battery they are powered from and generates a lot of heat. Is there any small brake I can use with the stepper motors I am using to get them to hold their position when there is no current being supplied?
The easiest way to do this is to add worm gear drives to motor shafts. Worm drive transmits rotation from worm to gear only, so it works as a brake in other direction.
Yes. You want a spring loaded brake that keeps the motor shafts from rotating due to spring pressure. The brake unit would include a solenoid that can be electrically energized to overcome the spring and release the brake. You would activate the solenoid just after you re-apply drive current motors. An appropriate delay will be required before commanding the stepper motors to move.
Probably the best thing to search for or build would be a clutch assembly that you would mount concentric with the stepper motors shaft.