... which means it's pretty much as dead as it can be. As I'm typing this, not one of the original wooden elements of the prototype has survived, fully delivering on the expectation that prototypes are not meant to last. In this case, the beamer arm prototype lasted for a single movie sitting before I realised that it was, on the long run, structurally unstable. More specifically, the single hinge took quite a lot of force. The inside pin is only 8 centimeters high and combined with the length of the arm, the construction makes for quite a lever. The top of the hinge started to come off the back plate, and, more worryingly, the top curl of the hinge started to open. Back to the drawing board then!
As a reminder, the current mechanism consists of a couple of parts. A single big hinge that connects an MDF arm to the wall. Then, a circle with two fixed side plates on top. The arm slides in between these plates. Below the circle, the beamer mount plate is fixed, which can rotate. The whole mechanism would fit in between two shelves in order for inconspicuous storage of the beamer.
I wanted to save the old hinge, as it was an expensive part. The obvious thing to do was to add a second expensive part (always dig a deeper hole): the same hinge but slightly less wide, which would hopefully alleviate the problem of the top of the hinge coming off the back plate. I had to reposition the old hinge, to make both fit in between the shelves, with as much space as possible between them in order to lessen the force exerted by the beamer arm. Now I could carve out a new arm, which would prove less heavy than the original one (partly due to the cut-outs, partly due to the use of a lighter type of MDF).
After painting the new arm I was almost done with the new version! All I had to do now was connecting the old mechanism (the circle with the two fixed side plates) to the arm and the system would be ready. Consider this version to be prototype 2, as I would quickly run into the next hick-up: the two plates connecting to the arm were too tight a fit, which was problematic when assembling everything when painted. The paint itself was adding an extra layer of thickness. It also added friction when sliding the mechanism over the beamer arm, which would damage paint on both of the components. I'd have to do a little bit of work to the mount-plate mechanism then...
The circle and the two side plates formed a solid block, glued together, which meant that my careful efforts to remove the side plates from the circle ended in total destruction of the piece. Fine. Rework those parts as well, and might as well make everything slightly better in the process! The beamer mount plate was shaved down a little to save on weight and a couple of other dimensions were modified.
I reworked the circle with two metal brackets instead of gluing the side plates, which alleviates the problem of the pinching plates, making it easier to slide the arm between them. It's a bit less pretty, but it's at least functional and can easily be adapted without tearing up the whole block. I only had to finish the rough edges of the wood with smoothening paste (Polyfilla), paint the elements and hope everything fit together...
All parts were ready for deployment, and thankfully no measurement errors popped up at the very end. I could install the mount much easier and more precise now, and after a bit of tinkering with the wiring I managed to get a pretty clean final system in place. Easily adjustable in each possible axis, the mechanism locks in place after deploying it in its view state. The only axis which is not locked yet (the angle of the main arm) can easily be manipulated by hand. I could have it be locked in place as well, adjustable and all, but as it's easy to do by hand it does not seem to be worth the effort.
Finally I can put this project to bed, it took me a while but I'm happy with the results. A couple of things I learned: