Stepper Motor Turntable Mount- EMS 4-26-14To address a problem condition that may be created when someone bumps the table or when power is switched of to the stepper motor, the following ideas can be used:
One option is to use an electrically released spring brake, and another option is to use a servo.
Arduino Sketch Code:
The cost of a new electrically released spring brake is beyond my hobby budget, but I found a used/surplus one to use that is within my budget. A new the brake costs between $165 and $200 USD, used you can find them for $40-$50.
The other option is to just call up another track to reactivate the stepper before you drive anything onto the unlocked table.
When you wake up the stepper/adruino with either a DCC or Analog command the brake will release and the stepper move the table to the position. Then after a short time out, the brake will set and the release will activate. In the stand-by state only the arduino is running and the brake and stepper are not powered
The brake is only there so that I can release the power to the stepper and have confidence that the table will still be in the same position when I move it again. The stepper does not move at all when released. If there is any mechanical binding in the turntable, it might move, but mine does not. I just want to ensure that if a locomotive drives onto the table or someone bumps the table it does not move. As the only reference for positioning is at start-up, any slight unintended movement would cause error until the table was reset.
Ok, so here is my drawing for a servo mount: