SLASH

SLASH #10 - String player
After more than a month, SLASH is back with plenty of work still to do and only 12 days left until the WRO! Today, I refined the overall aesthetics by applying the final color scheme and finally finishing the underside mechanism that plucks the strings using the small screen connected to the Raspberry Pi. All that remains is to complete the stand—which will hold the guitar upright and house all the electronics—and print everything out; then, the project will finally be ready for completion. Zagreb, here we come!

SLASH #9 - String Player
I’ve adjusted the servos and linear actuators for each string based on the precise measurements needed for perfect playability; I’ve also started building the external housing, it looks pretty ugly right now, but the screen and various decorations are still missing (let’s just pretend to believe in it).

SLASH #8 - Guitar CAD remaking and string player
I’ve finished the CAD model for the entire guitar, including the rest of the neck and the body, so I can get a full 1:1 view of the project. I also built a linear actuator from scratch for the MG90S servo used in the string-plucking mechanism; it works really well (I actually made a video of it but forgot to include it in the devlog lol) Now, I just need to finish the housing for the lower servos, adapt it to fit the Raspberry Pi screen, and complete the stand that holds the guitar upright while housing all the electronics.

SLASH #7 - General adjustments
I’ve made a few purely aesthetic adjustments to the system and loaded all the parts developed so far into Bambu Studio with the correct print settings to determine how much filament and how many hours of printing we’ll need (spoiler a lot).

SLASH #6 - Fret CAD Remaking
I’ve also finished the mount for attaching the servo system to the guitar neck and made a few general adjustments; the first version of the upper section is now completely finished. Now it’s time for the lower section, the part that plays the strings, which should (in theory) be simpler to build.

SLASH #5 - Fret CAD Remaking

I’ve finished the first version of the servo housing unit. I aligned each servo individually to ensure the best possible positioning for pressing the keys. I built a sliding-tray enclosure system: the outer casing opens, allowing the entire assembly of servos to be slid out for maintenance or adjustments. I also created an alternative servo configuration to allow for stacking units on top of one another; I simply extended the piston and its travel range. The next step is to create a magnetic mount to attach the system to the guitar neck, and then to revamp the lower section on the guitar body that plays the strings.

SLASH #4 - Fret CAD Remaking
I have, I believe definitively (I hope), completed the connecting-rod-and-crank system for pressing the keys using MG90S servos. It was much more complicated than expected due to the precise, millimeter-scale measurements, but I managed it! Now “all” that remains is to adjust all the servos on the guitar’s 36 keys and build the support housing around them.

SLASH #3 - Fret CAD Remaking
I’ve started working on the new key-actuation system; the previous version used electromagnetic solenoids that didn’t generate enough force and were very noisy, so I decided to switch to MG90S servos using a desmodromic cam mechanism. I’ve finished the first version of the servo assembly, but it’s MASSIVE, and I haven’t yet tested whether it actually works in practice. Tomorrow, I plan to continue laying out the servos on the guitar fretboard and running some tests with the initial 3D printed parts.

SLASH #2 - Guitar CAD Remaking
I have finished the guitar neck by adding the frets and strings. Installing the strings was tricky because they vary in both height and curvature and they are not perpendicular to the neck. The next step will be to develop the desmodromic cam system to actuate the strings using MG90S servos and to mount all the new motors in their correct positions.

SLASH #1 - Guitar CAD Remaking

I remade the guitar neck; the measurements are all irregular, so I used cardboard to create templates to follow.
I’m not entirely convinced by the result, but it should work.
I’ve mapped out the measurements up to the seventh fret and think I’ll stop there, that’s all we’ll need for our project.