As already mentioned in the article Replica of the IEC64 IEEE-488 board for the Commodore C64 and C128, I wanted to create a case to print out myself. This is what I want to do with this article. The corresponding STL files are available for download, so that anyone with a 3D printer can print out a suitable case for the board.
Such a naked circuit board may be functional and perhaps also practical, but beautiful is different. And you can't exactly call this protection. Personally, I think it's simply nicer if you have an appropriate case for a circuit board. And especially with this board this case has another advantage.
The cable that connects the IEEE-488 devices is not exactly a lightweight, let alone very flexible. These cables are rather stubborn and difficult to bend. The original Commodore IEEE-488 cable, which is included with the floppy disk drives, is the more flexible and light representative of this type of cable.
And only by the power of this massive cable it can happen that the board in the Commodore C64, or C128 can slip. Or even in the worst case it can be pulled out, and this possibly while the computer and the drive is switched on.
To minimize this, an appropriate case will help. This will fix the IEEE-488 interface card in place and prevent it from slipping out. Additionally it looks better and the board itself is protected.
For this purpose I designed a case with the help of a CAD program. The design focused more on functionality than on winning beauty prizes. In addition, one is also forced by certain specifications to adhere to certain things in the design. But I think that with this case I was able to do the balancing act between functionality and appealing design.
In any case, the first rendered picture of the case could already be seen.
The opening for the IEEE-488 connection cable is generously dimensioned. In addition, the interface for a ribbon cable is free, which I also provided reverse polarity protected by the case.
A first fast printout, here still with an unpopulated dummy board. Only to test the accuracy of fit the pin header and the DIP switch were attached.
The housing consists of two halves, which are simply plugged together and hold without screws. I have nevertheless provided two holes for a screw connection at the bottom, for example should a holding lug break later and the case itself can no longer hold together. Or also for those who want to be on the safe side.
The two case halves in the single view:
When trying to insert a populated circuit board, the socketed ICs unfortunately got a bit in my way. Because they are simply too high. But I can't make the case higher, because otherwise it can't be plugged into the expansion port of the Commodore C64 or C128 anymore.
If you take a close look at the board from the side, you will notice that there is still room for modifications.
Especially the EPROM has a lot of air between socket and component. To solve this is actually quite easy. With a small side cutter carefully cut the legs a good millimeter. The legs are long enough to avoid any contact problems. But don't cut too much, as I said, one millimeter is enough.
After the "circumcision" and the insertion of the ICs the whole thing looks better.
Now the ICs are almost sitting up. But that's quite enough. In addition, I also created some space in the top of the case by diluting the area above the EPROM a little. Cutting off the tips of all IC pins and diluting the area above the EPROM was enough to fit the board into the case without any problems.
In addition, I had added a retaining lug in the area of the IEEE-488 PCB connector, so that there was not such a big air gap in the case at this point. However, this had more aesthetic reasons, because otherwise I didn't like it that way.
The second printout wasn't long in coming.
Good one can recognize the recess over the EPROM. And on closer inspection also the additional holding lugs left and right at the wider part of the case, where the IEEE-488 cable will be connected later.
The small knob on the left side of the picture is later below the DIP switches. This is only for fixing, so that the board cannot be pushed through there, if perhaps too much force should be used. You can also see the two holes for a screw connection. The two halves of the case are clipped together and normally hold together by the small retaining lugs on the lateral guides. However, they cannot be seen very clearly on the picture.
When printing, there is actually nothing to pay special attention to. Support is not needed, at the most an apron can be printed, so that the corners do not rise during the printing. The material doesn't matter. I used PLA here, but you can also use PETG or ABS for printing.
Almost the whole thing looks like this:
It is worth using good filament. I had chosen for this expression a "cheap offer" of a well-known large mail-order company. Unfortunately you can see here quite clearly the favourable price of this filament. The first printout was made with the black NX2 PLA filament from Extrudr, which produced a much better quality. Unfortunately, the roll came to an end with the first print, so I had to fall back on the blue and inexpensive filament.
As always, the STL files can be downloaded free of charge from the download area.
Questions and suggestions can be left in the comment area. But I would also be happy about pictures of your printouts.
Translated with www.DeepL.com/Translator