Mod Mmm PCB for the IBM Model M

[dcpedit]

Long time lurker here, but first time poster!  Wanted to let every know that my new project is now on Github which allows you to use a PCB inside of an IBM Model M case!

https://github.com/dcpedit/mod-mmm

Here's the list of features:

• Hotswap sockets for MX switches
• Multiple layout support, including ISO, split spacebar, and 4x5 numpad. KLE link
• PCB mount stabalizers
• Under-switch LED for caps, scroll, and num lock
• Supports up to 3 rotary encoders
• Piezo buzzer
• Solenoid
• USB-C support via the STM32F411 Blackpill dev board.  Possibility of upgrading to the Bluetooth PillBug.
• Vial firmware

Also including some dev notes if you want to read them:

PCB curvature:  The curvature radius of the Model M's steel backplate is about 10.9 inches.  Flexible PCBs are super expensive, so for this prototype I opted for thinner FR4.  The risk is that traces/pads could break, and components can become damaged due to the stress placed on the board.  Converting all the components to through-hole might help mitigate this issue, and hopefully the large radius of the curve will cause less stress.
FR4 thickness:  Too thick, and it will be difficult to bend.  But too thin, and the hotswap sockets and stabilizers won't fit well.  I felt 1mm was a good compromise.
MCU board: I settled on the SMT32F114 Blackpill since it has the most usable pins in a form factor that fit on the daughterboard (I used EVERY SINGLE pin).  I was hoping that once the PillBug from MechWild came out, it could easily be converted to wireless.
Stabalizers:  I was worried that the curvature of the PCB would not work with PCB mount stabs.  I made the mount holes a tad bigger in the vertical direction to give them some more wiggle room, and it seems to work OK.
Hot swap sockets:  It was easier to test things during development with hot swap, but the sockets themselves did not provide enough holding power to keep the switches stable (at least with 3 pin switches).  I decided to design a plate for this iteration, which in turn also required plate foam.  Converting the switch sockets to solder-only could allow for more stable plateless builds.

Reddit discussion here

[Crabtree223]

Long time lurker here, but first time poster!  Wanted to let every know that my new project is now on Github which allows you to use a PCB inside of an IBM Model M case!

https://github.com/dcpedit/mod-mmmuno online

Here's the list of features:

• Hotswap sockets for MX switches
• Multiple layout support, including ISO, split spacebar, and 4x5 numpad. KLE link
• PCB mount stabalizers
• Under-switch LED for caps, scroll, and num lock
• Supports up to 3 rotary encoders
• Piezo buzzer
• Solenoid
• USB-C support via the STM32F411 Blackpill dev board.  Possibility of upgrading to the Bluetooth PillBug.
• Vial firmware

Also including some dev notes if you want to read them:

PCB curvature:  The curvature radius of the Model M's steel backplate is about 10.9 inches.  Flexible PCBs are super expensive, so for this prototype I opted for thinner FR4.  The risk is that traces/pads could break, and components can become damaged due to the stress placed on the board.  Converting all the components to through-hole might help mitigate this issue, and hopefully the large radius of the curve will cause less stress.
FR4 thickness:  Too thick, and it will be difficult to bend.  But too thin, and the hotswap sockets and stabilizers won't fit well.  I felt 1mm was a good compromise.
MCU board: I settled on the SMT32F114 Blackpill since it has the most usable pins in a form factor that fit on the daughterboard (I used EVERY SINGLE pin).  I was hoping that once the PillBug from MechWild came out, it could easily be converted to wireless.
Stabalizers:  I was worried that the curvature of the PCB would not work with PCB mount stabs.  I made the mount holes a tad bigger in the vertical direction to give them some more wiggle room, and it seems to work OK.
Hot swap sockets:  It was easier to test things during development with hot swap, but the sockets themselves did not provide enough holding power to keep the switches stable (at least with 3 pin switches).  I decided to design a plate for this iteration, which in turn also required plate foam.  Converting the switch sockets to solder-only could allow for more stable plateless builds.

Reddit discussion here

Even though I like the way the buckling springs feel and sound, I couldn't use them on a regular basis because of how heavy they are. This is particularly true given that I used to have repetitive stress injury (RSI). However, I am still partial to the more traditional appearance of the Model M, which is why I decided to create this modification. I am now able to use dimmer switches!