Since we are able to 3D print, CAD drawings have been used for rapid prototyping of the mechanism. Compared to cardboard mockups, this technique allowed us to limit the degrees of movement to the axes we are interested in. The chosen principle of combining a winch with levers is an intricate solution that benefits from precision techniques. A base plate mounted on the chassis holds the arms and guides the fishing line through control hoops. These serve the purpose of having the force more or less aligned with the plane of motion of these aforementioned arms.
In the middle a rotating spin plate is located, which feeds through the hole in the middle of the base plate. This adapter rod has a hole that fits with a Lego axle that connects to the gearing, as well as “milled” grooves, that allows a flexible clip to close around it in such a way that the base plate and spin plate is connected. This clip serves a dual purpose as the arm that triggers the micro switches that we use to safeguard ourselves from the motor losing its place. These micro switches are held in place with small brackets made with tight tolerances for clean snap fits. Both with respects to the micro switch and to the bottom of the base plate, in which 40 holes have been placed around the perimeter in such a way that we could determine our desired angle of rotation experimentally without being forced to reprint.
These holes serve as an interface for mounting brackets that can be screwed onto plywood for fastening the system, although we ended up janking a solution for lack of time. Other models we didn’t get to use were a bracket for the lego gearbox and the stepper motor
Additionally we have a top piece that sits on top of the control hoops with another snap fit. This piece serves two functions. First small clips printed separately for strength and flexibility are adhered with superglue, so the LED strip can be held in place. Second, a rod and crown adhered together holds the central lamp shade in place.