Approach
I came up with this project because I have a love for island culture and I wanted to challenge myself for my first 3D Printer design project. I began the design process by collecting some source material I could use to begin a design in Solidworks. I collected information on dovetail joints, proper spacing for a ukulele, and information on how to make a ukulele electric. I then was able to get the first iteration of my model finished. It is shown below.
Render of the 1st Design
Design/Prototype Process
After coming up with the main design, I needed to dial in my printer for some long (>12 hr) prints. I also needed to break up my model in Solidworks so it could fit on my limited build plate. I would then superglue the parts together after they were made to achieve the shape I wanted. This was needed because of the size as well as the shape of some of the parts. I wanted to use no support material for these parts. After finishing the parts and testing the fits, the main issues came with the pickguard, bridge, and volume knobs. The dovetail also required a minor change to the size.
First Design Prototype (Before the bridge snapped)
Pickguard/Bridge design Iteration
The main issue with the pickguard came with the capability to handle the string tension on the built-in bridge. After a bridge snapped off under string tension, I began to design a replacement to be glued on separately rather than built into the pickguard. This would hopefully prevent the layers peeling apart where they meet. I ran a FEA study on the new design and it held up well under the string tension. Despite the success of this new design, I wanted a wood look and thought a pre-made hardwood bridge would add this. It should also hold up well over time.
The other issue I had came with the placement of the bridge. Due to the size constraints, the pickguard was printed in two pieces and would flex under tension. I decided to beef up the back part of the guard by making a press fit, thicker design to mount the bridge on. This will limit any flex from the string tension.
I also needed to modify the location of the knob holes near the new pickguard to account for their larger size under the guard interfering.
Volume Knob Iteration
Covering the potentiometers with a volume knob proved an interesting challenge. I tried to use a model off of Thingiverse that another user made, but they did not have the same size for the press fit. I designed a few of my own and got the right clearance after 3 test prints. I pressed them on and it fit but still could turn on the potentiometer at the limits. I now noticed the reason for the slot cut out in the pot. After a quick re-design to add a rib in the middle, the knob was finished and fit well but was sitting too high. Instead of increasing the knob height, I made a spacer to place underneath to lower the pot. This made the knobs more aesthetically pleasing.
Results
I completed the project April 2019. The project turned out great and I am ready to get back to playing ukulele after my last model melted in my car when I moved. It taught me a little about iterative design, clearances, breaking up a model for 3D printing, and designing a project from scratch using source material. The ukulele sounds great especially for the first instrument I’ve made. Aloha!
You can download the files and see the parts list on Thingiverse: https://www.thingiverse.com/thing:3590824
