Other OpenAPS Pi+Hat cases didn't quite do what I wanted them to do, so I designed this one to hit as many goals as possible.
- Tough as heck. My rig in this case has survived falls onto concrete without issue.
- Screen protector.
- Pocketable. It's not small, but the smooth edges and rounded battery area make it much easier to keep in a pocket.
- Clicky, usable buttons.
- Tool-less access to microSD card, power plug, and power switch.
- Light pipes for increased visibility of charging and low battery indicators.
- Accepts commonly available 18650 batteries.
- High battery capacity, 6800 mAh with 2x Panasonic NCR18650B cells. I get 19 hours of battery without underclocking.
- Cooling vents, no overheating issues across several testers.
- Heat set threaded inserts for durability.
- Enhanced antenna performance with a (mostly) radio transparent window and an (optional) GSM sticker antenna.
- Size is 86mm wide, 77mm tall, and 25mm thick
Note: Both of the photos that show the opened case are slightly out of date. See the screenshot for the final design. I will update this with final photos as soon as I have time to build more.
Bill of Materials:
1 each of:
(Optional) 2 of:
M2.5 spacers screws and nuts
Keystone 209 contacts
M3 14mm hex cap screws
JST2.0 power leads
The above links are examples of the parts I used to make this case, but as suppliers for these types of parts change regularly, I cannot guarantee they'll work.
I am in the process of making batches of these cases for sale, for people without the supplies/tools/printer. If you're interested, please let me know and I'll prioritize production of these cases.
Basic Case Assembly:
- Push Keystone 209 battery contacts onto the printed Terminal pieces, making sure that the contacts are facing the correct direction
- Solder wire between contacts, routing it in the channel between the contacts.
- Trim red and black wires of power cable to length, allowing extra length for the negative wire to sit in the printed channel.
- BE SURE TO VERIFY POLARITY OF POWER LEADS! With the key/slot of the JST connector facing down, looking at it from the side with the wires, the red/positive wire should be on the right side. This means it will be lined up with the + marker on the explorer hat.
- Solder red wire of power cable to positive terminal on the side with the printed pointy bit. Solder black wire of power cable to negative terminal on the side with the printed pointy bit. Route the longer black wire through the channel to the negative side.
- Apply epoxy to the internal parts of the case where the terminal parts contact and insert them, making sure that the wire is routed out of the opening. Temporarily inserting 18650 batteries is a nice way to clamp it while it cures.
- Using a soldering iron, insert the 4 threaded inserts. I'd suggest practicing this on scrap plastic first, as it takes a little skill to do well.
- Cut a 30mm x 22mm piece of Lexan for the screen protector.
- Cut a 44mm x 26mm piece of Lexan for the antenna window.
- Epoxy both pieces of Lexan in place, taking care to not over apply epoxy to avoid oozing.
- Cut two short lengths of transparent 1.75mm filament and insert into light pipe holes.
- Either cut them to length with your rig inserted into the case, or leave about 3mm of filament inside the case while cutting it flush on the outside. Once you are happy with the positioning and brightness of the light pipe, either glue it in place or melt a small surrounding area with a soldering iron to permanently attach it.
Putting your rig in the case
Imgur gallery of illustrated and written step by step instructions
If you're making an OpenAPS case, you probably understand this already, but this was made and tested on a limited number of rigs. The goal is to make it easier to live with diabetes, via the DIY diabetes community. I'm confident in the design, but it's not my fault if it eats your dog or kicks your pancreas. Use common sense and caution.
I wanted to thank the people who helped this come together. Some were testers or early adopters, others provided useful suggestions or just regular old support. In general thanks to the members of the r/diabetes discord server but in specific thanks to, in alphabetical order:
Priline Carbon Fiber Polycarbonate
I used 4 perimeters for higher strength. Supports are only needed for the 4 screw holes on each case half. Depending on your filament choice and bridging performance you may need to support the micro USB holes as well.
All STLs are oriented in the proper directions for printing.