|original part - broken|
I smelled an opportunity for 3D printing!
The part that needed to be replaced was basically a hollow box with a protrusion that could be used to hang the whole clock on a nail. There was also a hole in the middle where the motor which turns the clock hands sticks through. Luckily, the housing which holds the guts of the clock gears was intact, except for a small part which held the battery contact. I just needed the hanger box and had to make sure it was a tight enough fit to push the battery contact against the battery again.
I used my digital caliper to measure the inside of the box. I added the thickness I wanted for the walls to come up with the outside measurement of the box - which turned out to be 61mm square, with 2.5mm wall thickness.
In my 3D Modeling app (Autodesk 123D Design) I created the 61mm square box - 16mm high - and hollowed it out from one side. This is super easy in 123D using the Modify, Hollow tool.
Then I put a 16mm hole in the middle (measured from the broken part) by creating a 16mm diameter cylinder and subtracting it from the center of the box.
A small rectangle was added and connected to the top of the box, with a tapered lower edge (to avoid a complete overhang which would not print well). I also tapered the sides outward to give it more hanging strength and then punched a 5mm hole into it to be the hanger so the whole thing can be hung back up on the same nail from where it fell in the first place.
BAM! after only one measurement fail - which I caught super early in the print - I had the clock box printed, electronic guts back inside, and the clock was back on the wall in that same spot we've been expecting to see it for the past decade.
This model will also be added to my list of "useful things" that I've made with my 3D Printer - gaining some credibility with people who think I'm just fooling around making only useless plastic trinkets ;)