The project I have proposed and completed an assembly model of is an electric guitar that was designed to be additively manufactured, due to the structural complexity making it difficult to produce conventionally. 3D printed guitars are becoming common due to the ability for customization, and often feature a hollow body with a webbed top. The sound of these guitars is not necessarily good, but they look really cool. Another downside is the cost of these guitars, as they are custom and are fairly large as far as additive manufacturing is concerned. The guitar I have chosen has a hollow body with working gears inside, a crosshatched top, and is based off of the classic Fender Telecaster. The project did not differ greatly from the original project proposal and was completed successfully on time. The original plan was to complete all parts and then assemble, but it made more sense to start assembling earlier and build and edit some parts in place.
The constrained assembly of the guitar has at least 25 unique parts, is fully constrained, and has no interferences. The gears and screws were similar to each other and were not counted as unique parts. All the parts have over four features. The version with motors has eight gears that are unconstrained and rotate via a motor. There is also a piston-cylinder assembly attached to the motor gear that pumps back and forth when the motor is on. A third file was created to manage the rendering, which was accomplished with KeyShot.
I started with the most complex parts, the body and the neck, and progressed from there. Dimensional diagrams for a Fender Telecaster were referenced continuously, as well as an actual guitar, to accurately reproduce the guitar to scale. The body crosshatch sketch was very intricate and time consuming. I began by projecting the blueprint of a Telecaster onto a sketch and tracing it using the curve tool. The body was extruded from this sketch and then thin-walled to leave room for the eight gears.
The neck was divided into three parts; the neck block that attaches to the body, the neck that runs almost to the fretnut, and the headstock including the fretnut. The neck block was created by extruding a sketch copied from the body part. From there, a loft was used to reproduce the varying-radius fretboard. Pegs were used to join the parts of the neck, in case it was ever 3D printed. This could be accomplished by printing in several parts and gluing together.
The strings were also difficult, as the pitch, diameter, and distance between strings vary down the neck. They were created using lofts and sweeps from parallel planes. Working within the assembly helped to line up the strings with the fretnut and the tuning pegs. The gears were laid out on the body to find their axis. This was accomplished by centering circles on the body where one gear’s outer circle was tangent to the other’s inner circle and visa-versa. There is a motor on the lower gear and gear relationships between each adjacent gear. The ratio was set using the number of teeth of the two gears, which leads to all the gears turning.
This project was valuable in teaching me discipline in organization and managing a folder of parts. I also learned a lot about the assembly environment and how to manipulate relationships to constrain parts and under-constrain parts that need to move. The Angle relationship was a new one for me that greatly helped, especially in aligning the gears so they do not interfere. Editing in place helped keep everything in line, so it was a good technique to learn. I was especially proud of the piston-cylinder assembly, which actually works, and is a motion relationship I have never used before.