“Goals of this project:
Create an instrument with two button decks using a single brain, but still allow for the portability that having separate devices allows.
Design a platform with interchangeable parts that can be modified or augmented without reprinting an entire case.
Build in a way that allows construction without access to (or the desire to use) a large volume 3D printer for parts. To that end:
The case walls, decks and panels are fastened together with wood screws rather than being printed in place.
Case walls share the same width/height dimensions and could easily be swapped with 1/2” x 3” (13mm x 64mm) hobby board.
Button decks and bottom panels could be constructed using flat 1/8” (3mm) wood project panels/acrylic sheets and a laser cutter/CNC machine (or some careful drill work with a step bit).
What was learned from this project:
I felt confident enough in the design to solder directly to the button lugs this time, and this may be my preferred method going forward vs. spade quick-connectors. It’s cheaper, the connection is more reliable, it takes about the same amount of time to assemble the wiring matrix regardless, and ironically I think it’s actually easier on the buttons…
Magnets are not an ideal solution for holding case parts together. The pull is both too weak to hold together for transportation , and too strong to allow for easy separation. Future redesigns will likely use a locking pin driven through from the case top or bottom.
Using DB25 connectors as an intermediary between the button decks and the micro-controller works amazingly well, and again may be my preferred method going forward, even when not passing signal through a case wall. Not needing to worry about damaging the micro-controller when re-soldering to different pins is a very real relief.
Notes:
Ideas for this had been brewing since the end of summer 2019. After months of testing, I am confident enough that Wicki-Hayden is my preferred note layout, but I was dissatisfied with the clumsy control button layout (and general poor quality) of the Melodicade Prototype #3, and decided to try designing something that could be assembled and reconfigured from smaller separate pieces, rather than printed in place and disposed of afterwards.
My original intention was to build this using wood and laser cut acrylic, but the idea of printing smaller parts flat had me curious to know if the annoyances of warping and 36 hour long print failures could be resolved doing things this way. Printing many smaller pieces is definitely easier, however the warping issues persist, and I somewhat regret not constructing this from something more durable than PLA.
I’m also not entirely happy with the control module layout, and may change or replace it in the future (at the very least to add a couple of LED indicators), but I’m happy enough with things for now to spend at least a few months playing!”