During the last weekend, I made some steps towards the realization of my talking skull, Geremia.
I completed the client ad server application that will drive the skull. A straightforward state machine that will poll different resources on the Internet and that will notify the Arduino board sitting in the skull to perform actions related to the notification (i.e., blink the LEDs that play the role of eyes, play an MP3 file to simulate speech and activate the servo motor to make the skull jaw move.) The server and the client are connected over a simple RS232 interface.
That was a couple of hours of coding.
It was about time to figure out how to install all of this stuff into the skull. There is enough space to host the Arduino board and the proto shield I assembled. Unfortunately, I could not fit the servo motor, no matter what I tried. There needs to be more space, and giving the servo motor a stable installation would be challenging. I used a DM996 servo motor because the spring holding the jaw is pretty strong, and I needed something with high torque. This is also why I had to implement a voltage regulator circuit on the proto shield while dealing with the Arduino 12 Volt external power supply, but this is another story.
My first thought was to abandon the moving jaw feature of Geremia. Thinking about it, I realized that it was the coolest feature of the skull, and I didn’t want to drop it simply because I could not find a viable solution. This is when you feel sad because you can’t resort to your father, that was a remarkable mechanical engineer. We could have had some great fun working on this. Again, this is another story.
I started thinking about a possible solution. After some time, I found that the only solution was to host the servo outside the skull, anchored to the skull base.
I grabbed my Remarkable and started drawing, not like a mechanical engineer but more or less like a first grader. After some time, I thought I had a solution. The servo motor would be visible behind the skull, but I can cover it with something. Geremia would look very cool with a fancy scarf.
I have my design ready, but how can I build it? I found that Fusion 360 is free for personal use. I have never used any 3D modeling software in my entire life. I downloaded it and installed it on my Mac. I grabbed a caliper I bought in China decades ago and started to make measurements on the servo motor and the skull base. I added the relevant quotes to my terrible drawing and was ready to model it on Fusion 360. It was mostly made of boxes with four holes to anchor the servo motor.
I viewed a couple of tutorials on YouTube on how to use Fusion 360, and a couple of hours later, I had my design ready.
I saved the file and opened it with Ultimaker Cura to print it on my FLSun Q5 3D printer. I adjusted a few parameters to strengthen the object and launched the print. Sunday morning, the print was finished. I need a few screws and nuts, and I will be able to assemble them with the servo.
While I was having lunch, I was thinking about what I did, and I was surprised. It is incredible what you can do with technology today. Knowledge is available to everyone with an internet connection. Twenty-four hours before, I didn’t know anything about 3D design, and now I have something I designed sitting on my desk.
This is highly fascinating, at least to me.