CoCo SDC Cartridge Case

thingiverse

This is a simple case design for the CoCo SDC, which is an SD card-based disk controller for the TRS-80 Color Computer series of machines. See http://cocosdc.blogspot.com/ and http://www.cocopedia.com/wiki/index.php/CoCoSDC for information on the peripheral. Print Settings Printer: Monoprice Maker Architect Rafts: Yes Supports: Doesn't Matter Infill: Probably 10%. Anything should do fine; it's designed to be simple. Notes: Needed to be resized to 1.065x to print at the appropriate size on my printer. Just make sure the supports on the inside of the bottom of the cartridge are coming out with the correct spacing to hold the card. If not, adjust the size so that they will. I printed it in PLA, but ABS might be interesting to try as well. Post-Printing The cartridge prints right at the absolute maximum size that will barely go into the slot on my CoCo 3, which is a bit more tolerant of large cards than my original CoCo, but this has been fine for me, since the cartridge looks a lot better if you sand down the outside a bit. So just sand it down to fit; it won't need much. The screw-holes were just invented out of thin air. I went to the hardware store to look for matching screws and it turns out that something called a #2 x 1/2" wood screw is a nearly perfect fit. The case is bored for five screws, but it friction-fits well, and you probably don't really need them. Use just one in the center post, use just the four around the edges, use 5 -- I did -- whatever seems good to you. You may want to be careful putting too large a screw through the center post, since you don't want to apply outward force to the hole on the inside of the card. The center screw-hole is the only one that actually travels through a cutout on the board. The cartridge slot has some built-in supports. These work fine on my machine and prevent you from needing the rather overly-complicated support system that your slicer would probably cook up for you. The slot is almost ok with no support at all, so even just the few supports I have in there are probably an overkill. Just take a screwdriver or a knife and carefully break them out when the part is done. How I Designed This I wrote this up using OpenSCAD, one of the cartridges and a game cartridge for reference, and initially a tape measure (because I lost my caliper); I replaced the caliper near the end of the project and used that for later measurements. It's designed with the following requirements in mind: It should be simple to print, because my printer settings still aren't perfect. It should protect the card-edge as much as possible without overly-complicating the design. It should allow easy access to everything I might need; that is the card slot, the LED, and the switch on the front, as well as the on-board microswitches just in case I get a Dragon.