Summary

This is a case for the most excellent KIM-1 recreation, the PAL-1 kit from Liu Ganning that you will find here on Tindie.

If you like this and want to incentivize me to make more, consider a donation.

There are two options. One with a battery compartment that allows the PAL-1 to become a portable computer, the other one is just a simple enclosure.

Print Settings

Supports:

Yes

Resolution:

0.2mm

Infill:

30%

Filament: Your favourite filament brand PLA Red and white

Notes:

Print the shells with the cavity down, using tree supports (because of the large area and the small details, regular supports are too dense, stick to the shell, and are very difficult to remove).

You will need the top shell and one of the bottom shells.

You may want to add pads on the four corners to avoid warping. These shells are large and take a long time to print.

Single colour printers: if you want to experiment with two-tone printing, print the keyboard legends first, then while keeping the bed hot between jobs, change filament and print the keys. The models (keys and legends) are the same dimensions and should center at the exact same spot. It’s really difficult, and you will fail again and again, but the result is worth it (I think). You could also print the keys upright (with supports) and use paint to fill the cavities.

For the PAL-1 letters on the top shell, I just printed the letters with a slight negative offset and press-fit them in the case (a bit of brute force on a flat surface helped).

On a multi-colour printer, all this is of course very easy.

Post-Printing

You will need:

• 2 x slide switches (20 mm x 8 mm with a 7 mm stem)
• 9 x 10 mm length M2.6 countersunk head tapping screws
• thin rigid insulated wire (I used the conductors from some network cable I had lying around)
• optionally, some dark gray or dark brown transparent acrylic (up to 3 mm) and a few cm of transparent 1.75mm filament.

If you are installing the battery:

• A rocker switch (18.5 mm x 12.8 mm)
• a 16850 battery
• a single 16850 battery holder
• a micro USB charging module (you want the modules that are sold without the USB A connector, or with a separate connector to solder, since we won't be using the USB A connector.)

Power Supply (battery option)

Do not install the battery in the battery holder until all connections have been completed and verified. These batteries pack a lot of punch and sparks will fly!

Solder two leads to the switch one RED (appx.15 cm or 6 inches) will be live and one YELLOW (appx. 20 cm or 8 inches) will get power to the PAL-1. Install the switch in the enclosure (bottom).

Connect the battery holder to the charging module, solder the battery holder leads to the B- (black lead) and B+ (read lead) pads on the charging module.

Solder the RED lead from the switch to the OUT+ pad on the bottom of the charging module. Solder one (appx. 15 cm or 6 inches) BLACK lead on the OUT- pad.

Solder the BLACK lead to a ground at the back of the PAL-1 PCB (at the DB-9 connector shield pad for example).

Solder the YELLOW wire coming from the switch to to the output pad (pin 3) on the 7805 voltage regulator (leftmost when looking at the back of the PAL-1 PCB with all the connectors up). We are not using the onboard voltage regulator as there already is a regulator on the USB module.

Install the USB module in its compartment and fasten it in place with the lock.

Install the battery and check that the PAL-1 powers on with the switch. Place the holder with its battery facing down in the battery compartment.

Route the wires that stay under the main PCB around the battery compartment.

Serial interface mode and memory modes switches (both options)

Solder two pairs of wires (from each of the jumpers on the bottom of the main PCB (remove the jumpers from the PCB, they won’t be needed). Those wires don't carry power, so they can be thin.

The wires from each jumper will pass through two notches in the bottom part to reach the slider switches installed on top.

Solder the wires to the switches and pay attention to the orientation to match the text on the top part.

Display Windows (optional)

With a utility knife, score the acrylic sheet on both sides to the size of the two LED display windows (I used the printed part as a template) and snap the acrylic to break it cleanly (wear eye protection!). You can sand the edges to make them smooth or to correct the dimensions.

Jam the two rectangles in their respective windows so they’re flush with the displays. It's supposed to be a friction fit.

Don’t forget to remove the protective film but only when you’re happy with everything: acrylic scratches very easily.

Power LED Light Guide (optional)

Insert a length of transparent 1.75 mm filament in the hole on the left of the display windows to serve as a light guide for the power LED. Cut it to length, remove it by pushing from the bottom.

Using a lighter or a soldering iron, carefully melt one end of the filament to create a clear lens. This side will stay on top.

Re-insert your light guide in the top case.

Tidying up

Install the PCB inside the bottom shell, making sure all the wires are routed properly (that’s why you want solid core wire). The PCB is 1.6 mm and the compartment allows for 2 mm. It's a tight fit.

Fasten the top part to the bottom using the seven screws. Make sure you don't pinch any wire in the process.

How I Designed This

This was designed using TinkerCad.

Change Log

20221009 - Bottom updated to remove lock

20231123 - Uploaded a bottom part without a battery