F Bomb

A 3d Printed Macropad

Designer's Note: This project is an exploration of the theme Information as a Weapon.

Intro

A 3d-printable macropad for your Fn enjoyment. It contains 12 Fn keys for your favorite Fn macros.

Why did I design this? I've been building a few 40% and 60% keyboards lately, and I've discovered I have a growing collection of Fn row keycaps with no Fn use. What should I do with all these Fn keys? A Fn macropad, of course! But why settle for a rectangular Fn keypad?

Project Structure

/stls - STL files for 3d Printing

Construction

Printed Parts

• 1x Shell
• 1x Base
• 1x Fuse

Hardware

• 12x Keycaps. Whatever Fn caps you have lying around.
• 12x Switches, presuming they fit in a 14mm square square hole. Cherry MX or compatible.
• 12x 1N4148 Diodes
• 1x Pro Micro
• Crimp terminals, housings (3 pin, 4 pin)
• 4x M3 x 8mm Countersunk Machine Screw
• 1x M3 x 12mm Socket Cap Machine Screw
• VHB or other double-stick tape (optional)
• Wire
• Heat Shrink Tubing

Tools / Misc

• 3d Printer + Filament
• Soldering Iron + Solder
• Multimeter
• Wire Cutters / Strippers / Flush Cutters
• Crimping Pliers
• Hex Drivers

Printing Notes

I printed mine at 0.2mm. The shell needs support - a lot of Fn support - but the base and fuse do not.

Assembly

Install heatset inserts into the fuse and shell. Attach the fuse to the shell with an M3 x 12mm screw from the inside. It's best to do this before you Fn wire it.

Wiring

I wired my macropad into a 4x3 matrix. Each switch gets a diode and ~100mm of wire. I did not want to reach a soldering iron inside the Fn shell.

I used Red for Rows, and blaCk for Columns. Each column wire gets a flag with a number, 1-4. I inserted the first row of four switches, and spliced the row wires together. This then went into a crimped conenctor. I repeated this for the remaining two rows, and then all of the matching columns. You do not want two switches with the same row + column.

Microcontroller + Firmware

Solder headers onto a Pro Micro and snap it into the Fn base as shown. I like to use a strip of VHB double stick tape to keep it from rattling loose.

Attach the matrix, figure out what pins you've picked, and flash that Fn thing. I use QMK firmware

If all the Fn keys work, shove the wires into the shell as best you can, and screw on the base. Give yourself a Fn high five.