Project “Maxi-Switch Medley”

[picturamundi]

Taking inspiration from @Rico’s recent project chronicles on here, I’ll venture sharing something. But only because I’m now at a point where I’m reasonably confident it won’t be a total fail.

I want to retro-fit my Maxi-Switch 630107-02 so that it can take MX switches (the OG switches are crap) and communicate over USB / Bluetooth. I’m calling it “Maxi Switch Medley” both because the project will be a mix of old and new, and because I’m hoping the final product will sound quite musical given its acoustic features.

No AI was used in the making of this image

A few practical reasons why I thought this keyboard would be a good candidate for a retro-fit project:

• The keycap mounts fit MX-stems if you use a plastic film mod. Noticing this was what first gave me the project idea, since otherwise making custom keycap adapters just wouldn’t have seemed feasible to me. With the Maxi-Switch, all I have to do is order MX stem risers for keycap clearance.
• The case is also extremely roomy, making it ideal for adding a LiPo battery of pretty much any size, maybe eventually a solenoid, or any other components I want.
• The keyboard case has a big access hole at the bottom where it looks like it might have docked onto a terminal or something. This makes it really easy to switch to a USB-interface without the finicky job of making the new hardware fit old port sizes and placement.

There was massive ribbon cable hooked up through this hole, I removed it

1. Keycaps

The first thing I did was order MX stem risers since keycap compatibility is what would make or break the project, as far as I was concerned.

Left to right: MT3, SA, C64 + MX adapter, Maxi-Switch + MX riser

The risers do work, although I am a little nervous to find out what it will feel like to type on something with this sheer amount of height for extended periods of time. For comparison, my keycaps will be as tall as if you stuck an SA set on 4mm risers.

2. PCB

Next up was to see if I could wrap my head around designing a PCB in KiCad, which I’ve never done before.

I tried to keep everything as simple and basic as possible. I chose to use a Pro-Mico footprint. In order to accommodate such a large keyboard (19 columns) with only 18 GPIO pins, I had to do some matrix folding on the PCB, but that seemed worth being able to stick with a widely supported and widely understood footprint.

The PCB arrived last week:

I’ve done some basic continuity testing with a multimeter, but haven’t yet been able to fully test the PCB with firmware.

3. Firmware

I picked ZMK as my firmware so that I could use a nice!nano and have the option to go wireless in the future. While I have used ZMK before, I’ve never had to define a new matrix and new physical layout before, so figuring that out was new:

Late last night I was finally able to get the firmware to compile successfully, which is a relief. After the PCB, that’s what I was most nervous about not being able to figure out.

I have been making my way through my to-do list in decreasing order of what seems most challenging, so I feel reasonably good about what’s left.

To-do list

• Order stem risers and confirm keycap compatibility
• Design and order PCB + other components (diodes etc.)
• Compile firmware
• Design and order switch plate + spacers etc.
• Assemble, test, and troubleshoot

All for now!

[wjrii]

@picturamundi

Taking inspiration from @Rico’s recent project chronicles on here, I’ll venture sharing something. But only because I’m now at a point where I’m reasonably confident it won’t be a total fail.

I love this so very much! It looks like it’s actually going pretty smoothly, and with the way some pre DIN switches are designed, I bet it won’t work badly at all. Maybe just track down a switch known for not having much wobble.

For ZMK, I like genteure’s Shield Wizard a lot, though the Pi Picos I’m also fond of don’t seem to like to save their Studio-modified keymaps between reboots, so my last firmware was slogging through QMK with VIAL. For a Nice!nano or clone, I think it would work really smoothly, not that you need it now, LOL.

How was shipping and tariffs from the PCB fab?

[Rico]

Very nice project!

You did very well for your first PCB design

I never used ZMK, I am really curious how easy/hard it is to design a firmware on it.

Can’t wait to see the final result!

[picturamundi]

@wjrii

genteure’s Shield Wizard

NOW you tell me this exists??

@wjrii

How was shipping and tariffs from the PCB fab?

I paid a $30 tariff on a $60 PCB, so that was annoying.

@Rico

You did very well for your first PCB design

Thanks! That’s what I like about this hobby; I can do something very basic, and people who know a lot more will still be encouraging.

[picturamundi]

I finally decided to tackle getting a switch plate made for this. I went to a shop in a nearby town here in CT and asked the owner if he’d do it. He was clearly a little annoyed at the request. It was a small business, but they were still quite busy churning out heavy industrial parts. “I say no to individuals who walk in here, because you’ll take an hour of my time, and then what am I supposed to do, charge you $400 for your part because I had to pause a big job?”

In the end he said yes. Then he spent a half hour grumbling and cussing trying to figure out the file I brought in, getting it to work with whatever ancient software he’s running on his Windows XP machine, failing, and trying again. I would have felt more bad about it if it wasn’t so funny.

When my design was finally ready for production, he had one of the employees pause a machine that was in the process of laser cutting a huge, half-inch thick plate of steel. When I asked what it was, he said “We make a lot of housings for different heavy artillery. Most of this goes to Ukraine.” It took two guys to haul away this piece of steel to make room for my 1.5mm thick sheet the size of a piece of printer paper.

While my plate was being cut, the owner, Dana, gave me a tour of the whole shop and the warehouse, showing off the the replacement parts they make for old mustangs, the huge tank they welded for an oil-rig off the coast of Hawaii, telling me his life story, and having a grand old time.

In the end he charged me $20 and gave me a firm and friendly handshake. The switch plate fits perfectly — v1 of the keyboard is almost complete.

So anyway New Englanders seem pretty gruff at first, but Dana here will literally pause sending aid to Ukraine in order to give you a hand.

[Rico]

What a cool story!

[wjrii]

Love this! I gotta find me a gruff old salt with a heart of gold to charge me materials only on a fiber laser.

[Wooden-Toilet]

I don’t know what voodoo magic you did on your post but I legit was able to picture scenes in my head while reading your story. It felt like I was watching a scene from a TV show.

[picturamundi]

@wjrii

I gotta find me a gruff old salt with a heart of gold to charge me materials only on a fiber laser.

So the reason I tried this is actually because I saw another hobbyist share their experience and recommend it as an approach. As usual I can’t remember who or where it was, but they said a local company cut their plate for $10-$15. They didn’t mention the size or material, but still.

@Wooden-Toilet

I legit was able to picture scenes in my head while reading your story.

Maybe it’s because I wrote it right when I got home, which allowed my utter delight and amusement, still fresh, to seep through a little ^^

[picturamundi]

Maxi Switch Medley v1 is complete!

Here it is making its maiden appearance at a recent mini meetup in Glastonbury, CT.

For the meetup I put Zeal Clickiez in this, and as one person at the meetup said, “wow, a build where using Clickiez actually make sense.” They’re a great pairing with this board, especially acoustically. After the meetup I switched to BOX White v2 for better usability.

While 100% functional (I’ve been using it at work for days), I should quickly add that v1 of this project is quite rough around the edges. I wanted to keep things very simple to begin with because it’s my first project, which worked well for me. But I can already think of quite a few things that could be improved with a v2.

First, some fixes:

• The PCB switch footprint for backspace is off by 1/4 unit. This is because I assumed that the backspace, like every other non-stepped key, has a centered switch. It does not. No one at the meetup noticed… but I definitely do.
• The spacebar stabilizers don’t properly snap into place right now because they need more clearance between PCB and plate than what MX offers (currently they’re superglued). I could easily fix this by putting holes in the PCB below where the stabilizers are, allowing them to poke through.

Possible new features:

• Both a reset/bootloader switch and an on-off switch for the microcontroller would be nice, especially if I could design that into the next PCB to keep things tidy.
• Not all the symbols on my keycap legends match a modern QWERTY layout, which is a little annoying. But I have spotted a Maxi-Switch 630107-02 drop-in replacement keyboard on eBay with the right legends. It would be cool to snag that and swap out some keycaps.
• I’m thinking of a new case bottom. I like the case top a lot, but the bottom is too tall and also too sloped to be ideal, and most of it is empty space. I’m a big fan of the case style on the Leading Edge’s keyboards: big bezels, but not a lot of depth and only a slight incline. Getting something along that lines 3-D printed could be fun.

All for now! …despite my urge to make this an even longer post just so I can keep typing away on this thing.

[veeraj1]

I agree