I wanted a new bracket system for my Shark HD CNC pendant that would allow me to fold the pendant out of the way when not in use, and secure it in position when in use. It needs to lock because otherwise, the pendant touch screen would close when used. You may find the concept useful for other projects where you need a locking hinge system.
I had some (self-inflicted) criteria for the project:
* Make it out of 1/2” BB plywood
* Able to turn 90º from the open to the closed position
* Lock when open to prevent movement
* Few moving parts
* Manufacture the parts using only the CNC
After going through several design iterations, the final solution was a wooden hinge with one long leaf (the bracket arm) and stepped knuckles on the other leaf (the bracket support). The bracket arm sits on the higher step of the support knuckles when in the closed position and drops onto the lower step when in the open position. The higher step prevents the hinge from folding when in the open position.
My next challenge was how to use the CNC to drill a 2” long hole in the bracket arm for the 10-24 machine screw I’m using as a hinge pin. My solution was a long groove on each half of a lap joint which creates the long screw hole after gluing the overlap. With the CNC it was easy to cut pockets half the thickness of the plywood for the lap joint with slightly deeper pockets to make the grooves. I used a 3/16" ball nose bit for the grooves.
Assembly was merely a matter of gluing the two stepped knuckles into mortises cut in the bracket support and gluing the lapped pieces together to finish the bracket arm. The machine screw hinge pin, with enough slack to allow up and down movement of the bracket arm, completes the hinged bracket. It's easier to understand from the video than from my poor description.