The CMD accent plates front and back are the parts which I am least happy with. Whilst they look great on CAD, helping to split up and define different parts of the cameras design, I obviously spend a few hours too long staring at the screen rather than trying things in real life. By the time I came to making this part, I realised I'd made the thin section which wraps around the dials 1mm thick. 1mm. That is just so thin. Unsurprisingly this made it a pain in the arse to machine.
I started out with a nice blank sheet of 3mm acrylic. Using the milling machine I worked the top face down into the profile I needed. The thickness of the shallowest part is a simply massive 1mm.... I had to use a small tool and take very small gentle steps down into the plastic to prevent it from tearing through. You can see in the screenshot at the top that the green cutting path whizzed around all the components with a lot of cross over. In the end this was all done with a minute 2mm end mill cutting bit.
At the time I was making these parts I'd been on the machine for 2 weeks and was getting tired, and to make things worse I had a succession of things flat out failing on me. Multiple parts just snapped while machining, or while I was trying to remove them from the board after they were finished cutting (there were double sided taped down). A milling bit snapped, and I was just staggered because A. I didn't know how or why it happened, and B. there was no trace of the bit which had snapped, it had just vanished!
Then incase I wasn't getting exhausted enough the machines started failing. First the FDM rapid prototyping machine which I was using at the same time decided to just give up and print fresh air, and then I was left wishing I had more fresh air when the building air compressor overheated, cut out, and froze all the air supported machines in the department including the HURCO.
Eventually I started getting parts out in one piece. With a front and back plate needed for each of the 3 models, machine time was high and I spend a long frustrating few hours nursing the machine to ensure it didn't destroy the delicate parts. I was going to do 2 sets in white and 1 in black but after three separate attempts at cutting the black plastic, I concluded it was to brittle and a waste of my time, with each part snapping.
