The 3D Printed Case

A project log for Digital Magic 8 Ball (Mk.2)

One of my first projects ages ago was a Digital Magic 8 Ball on a breadboard ...

sjm4306sjm4306 12/19/2020 at 18:530 Comments

So in a similar design vein to the programmer's converter dookickie I made a little while ago I decided to design a little bottom shell to house the bare pcb. For simplicity's sake I wanted to have a friction fit with no glue or fasteners required. To achieve a snug fit I referenced the pcb files to get accurate location dimensions and added about 0.5mm clearance between the pcb/components and the shell in areas where they would contact.

Additionally, in keeping with the 8 ball theme it'd have to be round but also have a flat bottom so it wont roll off the table (and be easily printable without supports). All these requirements led to a puck like shape with rounded corners and an inset void for the pcb to sit inside. I also borrowed the rear CR2032 battery hole from my converter design so it'd be easy to change the battery without removing the case.

These ideas condensed into this design.

Sort of looks more like a donut than an 8 ball but function over form I guess lol.

Printing took just under 2 hours on my Creality Ender 3 Pro and used 14g of black filament. The fillet on the bottom was 10mm but my printer was just barely able to print the overhang with a tiny bit of curling on the surface (in retrospect adding support or making the fillet less extreme would have solved this problem).

Pushing the pcb in was nothing short of satisfying. Everything fits as snug as a glove without being too tight. Here's how the end assembly looks with the pcb installed.

As a final note, I decided to leave the top uncovered. It'd be easy enough to design and print another piece that sits over the top with holes for the oled and button, but I kind of dig the look of the exposed black pcb with gold exposed metal pads and the screen and button are just about level with the top lip of the plastic. As for now I'll upload the solidworks and stl files for this print as I'm happy with the end result.