Final prototype
I used an old autoharp to make my final prototype, repurposing it. I’m not certain of when this was made, but it seems old. It’s covered in dust, cobwebs, and feels fragile despite being made of wood. It uses nails and glue in its construction, and most metal parts are covered in rust.
I first took the instrument parts, including the front, where the strings were held. After this, I cleaned the body and parts, including removing some rust.
I put the sides back on to attach my electronics and parts onto them and placed the sticker back on for aesthetics. I also put new tuning pegs in and added some sympathetic strings to experiment with adding more resonance. I also placed a piece of pallet wood in the gap left from removing the front that I drilled holes into for the strings to stay in.
I then started working on the mechanisms of the instrument and how it would work.
Here is the final prototype.
Evaluating this prototype, it has more flaws than uses despite it working. Here are the main issues with it.
To start, the motors are too large and make it hard to place them down, reducing the number of strings I can use. Because of this, they also get in the way of each other, and the 3rd motor constantly hits the 4th. Also, this means the exciter has to be quite long, and that reduces the sound, and it sometimes hits other strings.
The sliders didn’t work consistently, which is due to the rails above them. While I think this is the best solution and is what I will do further, the material I used is too flimsy and bends whenever a knob is pulled or pushed. The sliders themselves were alright, but the material wasn’t good enough. A metal or glass slider works much more effectively, as seen in guitar sliders, and this is the route I would have to go down.
The electronics were not too bad, but due to negligence of the circuit, when one motor was powerful enough, the other motors would slow down. This is because I made a parallel circuit when a series circuit would be more effective. I did make this in a rush and wasn’t too proud of the electronics, so when making this again, I need to fully design a more effective circuit. Another thing to note is I haven’t been using a soldering iron, this means the wire can move around and is less consistent. While I know this is better, I’m honestly scared of soldering irons due to their heat, but this is mainly due to a lack of use with them.
The body was fine, but the MDF I used was extremely flimsy (as stated with the sliders), so when I do this again, I need something more sturdy.
Finally, the tuning pegs worked fine but did lose their pitch at times. I’m not too sure why but id assume the threads of the holes were weak due to the age of the autoharp and the brittleness of the wood. For the future, I need to research better tuning pegs to hold their pitch better, this is needed as the strings take a lot of abuse when being hit hundreds of times a second and will be prone to detuning.
Along with this, my documentation process needs to be better. I forgot to take some vital photos. I thought making a video of the build process would help this, as I would have to record every second of what I’m doing for it to be coherent.