Everyone’s favorite potassium packed, slightly radioactive, 105 calorie macropad is back! This time in a split wireless version. 3d print your own today!
Q) Again?
A) The opportunity was ripe for the taking.
Q) How will I know if a split macropad is right for me?
A) You’ll peel it in your bones.
Q) Should I lube my switches?
A) Go for it, but try not to slip!
Q) Is this ortholinear?
A) I would argue it is the most ortholinear of all the fruit.
Q) How do I introduce myself in polite banana company?
A) “Yellow, everyone.”
Q) What’s your favorite programming language?
A) Not sure if I have a favorite, but Javascript is ('b' + 'a' + + 'a' + 'a' + 's')
Q) This FAQ is causing me physical pain.
A) You can plantain all you want, but the puns will not stop.
A big thank you to Keebio for releasing an awesome set of KiCad libraries for keyboard components. This saved me a ton of work.
- 1x top_left.stl - https://github.com/dbostian/bananasplit/blob/main/stls/top_left.stl
- 1x top_right.stl - https://github.com/dbostian/bananasplit/blob/main/stls/top_right.stl
- 1x bottom_left.stl - https://github.com/dbostian/bananasplit/blob/main/stls/bottom_left.stl
- 1x bottom_right.stl - https://github.com/dbostian/bananasplit/blob/main/stls/bottom_right.stl
- 2x fruit_slice.stl - https://github.com/dbostian/bananasplit/blob/main/stls/fruit_slice.stl
- 1x battery_clip.stl - https://github.com/dbostian/bananasplit/blob/main/stls/battery_clip.stl
- 1x Banana Split PCBs - https://github.com/dbostian/bananasplit/blob/main/pcbs/banana_split.zip - I ordered mine from Osh Park
- 1x nice!nano - https://nicekeyboards.com/nice-nano/
- 1x 301230 Battery, with JST connector
- 1x JST Pigtail
- 1x SPDT Switch (PCM12SMTR - Digikey 401-2016-1-ND)
- 2x 12 pin Machine Sockets, Standard Length (Mill-Max 310 - Digikey ED11164-ND)
- 24x Machine Pins (Mill-Max 3320 - Digikey ED1134-ND) - order some extras
- 2x TRRS Jacks (PJ-320A)
- 8x Diodes (1N4148)
- 8x Switches - Cherry MX or compatible
- 8x Keycaps
- 1x TRRS Cable
- 1x USB C Cable
- 1x Sticker (not optional)
- 6x M3 x 16mm Socket Cap Machine Screw
- 6x M3 Heat Set Inserts
- 3d Printer + Filament
- Soldering Iron + Solder
- Multimeter
- Wire Cutters / Strippers / Flush Cutters
- Hex Drivers
- ZMK Shield - https://github.com/dbostian/bananasplitfirmware
I printed mine in PETG at 0.20 mm layer height and with 15% infill. Enable support material for the shells. I used ironing to get a nice finish on the fruit slices.
The nice!nano documentation recommends a cool-ish soldering iron temperature - and also recommends triple checking your battery polarity. Please give this a read.
First, install the heat set inserts into the top shells. The ones nearest the middle should be installed deep enough so that they clear the PCB.
Solder the diodes, TRRS jacks, and power switch to the PCBs.
Next, solder the machine headers to the board. I used the MCU to establish position as I soldered the corner pins into place, then removed it before soldering the remaining header pins. Then, solder the MCU to the pins. Use tape as suggested in this socketing guide to prevent permanently attaching things. Note that the tiny b+ and b- holes are not used.
Attach the JST pigtail to the PCB. Leave the battery disconnected during this step. Trim the back side of the wires flush.
Gently pry the MCU from its socket, and set aside. Snap your switches into the top shells and solder the PCBs in place. Reinstall the MCU.
Now’s the time to flash your favorite firmware and test. I am using ZMK - you can clone my sample firmware repo here. Running other firmware? The switches are wired into a 2x4 grid, connected to digital pins 8 & 9 (rows) and 4, 5, 6, & 7 (columns).
Connect the battery and secure it into the base with the clip. Assemble the 3d printed shells using M3 screws. Don’t forget the decorative fruit slices!
Lastly, add your keycaps, apply the sticker, connect the halves with the TRRS cable, and enjoy!
