Kung Fu Flash Case (Rev 1 & 2): buttons for any switch height, logo or label top

A screw-together case for Kim Jørgensen's Kung Fu Flash cartridge for the Commodore 64 and 128. It fits the micro-USB boards, PCB Rev. 1 and Rev. 2, with the same files. Every board dimension comes from the official KiCad design, and the fit was checked against it part by part. Everything prints without supports.

Why this case

• Buttons for any switch height. Builders fit 6 × 6 mm tactile switches anywhere from 5 to 13 mm tall, but a case usually suits one height. Here there is a button file for every height from 5 to 13 mm, and the case is the same for all of them.

• Buttons that stay put. Each button goes into the top half from inside, and a rim round its base stops it falling out through the hole. A D-shaped head stops it turning. It rests loosely on its switch with a small gap, so it never holds a switch half-pressed and nothing needs a tight friction fit.

• A solid board. The screw clamps the board on the centre post, and a support sits under every switch, so pressing a button pushes into the case instead of bending the board.

• Opens as easily as it closes. One countersunk screw holds it. A lip on the bottom half lines the halves up, and they drop together without forcing. There are no clips to snap or pry apart.

• Reach the SD card without a shorter case. A finger scoop in the end lets a fingertip push the card in and press it to release.

• See the LED. A light pipe of 1.75 mm clear filament sits right over the status LED. A cutting jig is included for a square, exact-length piece.

• No supports anywhere. The edges are 45° chamfers, and the label or logo forms on the bed.

• One set of files for Rev. 1 and Rev. 2 boards.

• CC BY-SA 4.0: remix it and share it.

Choose your buttons

Measure your switch from the board's surface to the top of the plunger: that is the H in 6 × 6 × H. Print three of the matching button.

• 5 mm switch: kff-button-for-5mm-switch.stl

• 6, 7, 8, 9 or 10 mm switch: the file with that number

• 11, 12 or 13 mm switch: the file with that number. On these the button stands a little higher (1.8, 2.8 and 3.8 mm instead of 1.4 mm) because the plunger itself is taller.

Short switches get a stem down to the plunger. Pressed, a button never touches the switch body.

Two tops

• Label top (kff-case-top-label.stl): a 54.5 × 14 mm recess for a printed label.

• Logo top (kff-case-top-logo.stl): the Kung Fu Flash logo recessed 0.6 mm into the top, with S, M and R beside the Special, Menu and Reset buttons.

The bottom half is the same for both, with a plain face. Both tops print face down, so the label recess or the logo forms on the bed.

Other details

• A micro-USB opening in the side, stiffened on the inside so the thin wall above it doesn't snap.

• Ribbed finger grips on both sides near the back end, which stays outside the C64, so you can grip it to pull the cartridge out.

• A standard C64 cartridge mouth with a bevelled lead-in.

You will need

• One M2.6 × 16 mm countersunk self-tapping screw

• About 10 mm of 1.75 mm clear filament for the light pipe

• A small drop of superglue

• The board's J1 and J4 pin-header positions must be empty, as on most built boards. A fitted header is too tall for any case.

Files

• kff-case-bottom.stl: print 1

• kff-case-top-label.stl or kff-case-top-logo.stl: print 1

• kff-button-for-<H>mm-switch.stl: print 3, where H is your switch height

• kff-lightpipe-cutting-jig.stl: optional

• kff-test-piece-buttons.stl: optional. The button end of the top half, to try the buttons on your switches before printing a whole top.

• kff-test-piece-logo-top.stl: optional. A thin plate with the logo and letters, to check your first layer before printing a whole top.

Print settings

• 0.4 mm nozzle, 0.2 mm layers, PLA or PETG

• No supports

• Every file is supplied in its print orientation: the case halves outer face down, the buttons base down, the jig flat.

• For the logo top, use a normal first layer. Too much squish narrows the recessed lettering.

Assembly

1. Lay the top half face down on a flat bench. Drop the three buttons into their holes from inside, head first, with the flat of each D toward the connector end.

2. Cut an 8.4 mm piece of clear filament in the jig. Drop it into the light pipe from inside: it slides down to the bench, so it ends flush with the top. Put a small drop of superglue through the side hole in the light-pipe tube and let it set. Superglue fumes can fog clear filament, so keep the drop small.

3. Lay the board in face down, so each switch's plunger goes into its button.

4. Lay the bottom half on, with its pin through the board's hole. Hold the halves together, turn the case over and fit the screw.

Using the jig: lay the filament in the groove from the FEED end, through the guide block. Put the blade in the slot and cut to square the end. Push the filament up to the STOP and cut again, keeping the blade against the slot face nearest the stop. The guide block holds the blade square before it reaches the filament.

Credits and licence

• Based on the C64 cartridge case by Laurence Gonsalves (xenomachina), CC BY-SA 4.0. This remix is CC BY-SA 4.0 too.

• Kung Fu Flash logo © 2019 Kim Jørgensen, from the KungFuFlash project (codeberg.org/KimJorgensen/KungFuFlash), zlib licence. Altered: scaled and simplified for printing.

• This is an unofficial case. It is not made or endorsed by the Kung Fu Flash project.