Retro CPC Dongle – Part 46

It’s time to create the enclosure for the CPC2. This is my first foray into the world of 3D printing and it was quite daunting at first. However, free online software like TinkerCad make the process of creating a model fairly simple. I chose to start by creating the base that would hold the main PCB as this would likely be the most difficult piece to get correct, mainly because the cut-outs for the ports had to line up correctly. I ended up with this:

When printed, it gave me this:

Click for a large image

Not quite right, but almost! The holes for the HDMI and USB don’t quite align. To be fair to me, I was working from the mechanical design, rather than measuring the actual board that I built, so it’s not too bad.

One of the problems I have in testing the board fit is that there are two pin headers on the bottom of the board for the ESP32-Wroom32 and the FPGA, so it won’t quite fit onto the mounting pegs for a flush fitting. My plan is to build a second board that will connect to the main board with pogo-pins and remove the pin headers completely. That way, the same board can sit low in the case when in use and sit on the pogo-pins for testing and programming. This also means it must be easy to remove the board from the case and return it when programmed as it will flop-flop between the test harness and the finished case as needed for system programming.

Without spending time to really understand the capabilities of 3D printing, I opted for a conservative design for the enclosure. It will be a three part-piece comprising the base shown above, the top and the keyboard. It could probably have been done with two pieces, but would require support structures and have been a lot more difficult to print.

With businesses across the world struggling with COVID related problems, I really wanted to support my local businesses, so I used an Aussie printer, http://3dprint-au.com/ to print the part for me. It was a little more expensive than buying from overseas, but helping out local businesses in a tough year is the right thing to do.

I considered buying a 3D printer, but I’d need to create 9 pieces before I broke even at $50 per print vs a FlashForge Finder. I may still do this, given the lead time it takes to get a manufactured print and the chances of me screwing it up a few times.

The other discovery that I made when creating the model for the base is that to maintain the correct proportions for the CPC2 with the original CPC, is that it needs to be quite long. Anyone that knew the original CPC464 knew how long these machines are. You can see the location of the board pins in the image above, and everything outside of these is empty space. However, for the CPC2 to look like a miniature of the original, it needs this space added to be proportional. Sadly, it makes the final outer dimensions a lot larger than I wanted, and not exactly a dongle any more.

However, at this point, I’ll just be glad to have the project finished. I hope to have the programming harness built for my next post, so until then, stay safe!

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