This is a fully parametric 3D printed fixture that allows to open and close a ball valve with a servo motor. Designed with FreeCAD to be sturdy and easy to assemble. Compared to solenoid valves, this kind of valve requires much less current to operate, can be turned off when not in use, and works reliably on a 5 Volts supply, making it ideal for embedded projects.
- A standard-sized, high-torque, metal-geared servo motor. Higher torque is better to counteract initial friction in the ball valve. Up to 40 kg-cm servos are readily available in the standard size. 30+ kg-cm is definitely recommended;
- A circular, metal horn for the servo, with at least two attachment screws;
- A regular ball valve, that opens counter-clockwise and has a thin stop-notch;
- Two tie-wraps to tie around the pipe;
- Two to four screws to secure the servo against the plastic bracket.
- The part of the coupler that is screwed onto the valve should be printed at 100% plastic fill to prevent stripping of the square hole;
- Other parts can be printed with 30% fill. Mileage may vary;
- The servo mounting holes are typically 4.5 mm in diameter, which fits M4 or #8 screws well;
- It is recommended to have a way to power off the servo a few seconds after activation, to prevent overheating;
- Alternatively, use the play between the two rotating parts to move the servo backwards a bit after you open/close the valve. The "gears" are then loose and the servo is not applying any force on the valve.
- For example:
- Open: 2100 µs -> Wait 2 seconds -> 2050 µs
- Close: 700 µs -> Wait 2 seconds -> 750 µs
- For example: