‘C Major Scale’ Piano Model
For our final project, we decided to create a model of a piano. Specifically, we wanted to mimic the playing of the C major scale (the seven white keys) with a glissando-type movement. After several hours of designing and iterating, we were able to create a piano model whose keys move in a wave-like motion with the rotation of a crank.
Video of working model: https://drive.google.com/file/d/1tn27piXHZ1S_ybQwtWMW7KbcHzvlDvuq/view?usp=sharing
*Turn volume on for some ASMR 🙂
Initial Design
2D vector drawings were our priority when beginning to create the model. We designed several different pieces that we felt were necessary to make the model functionary. These different pieces were the bases, side supports, the piano keys, ‘key pushers’, ‘connectors’, ‘figure 8s’, and the crank.
Cardboard Prototyping: Fixing Issues with Sizing
As soon as we finished up our initial vector drawings, we began to cut the pieces out of cardboard using the laser cutter. This ensured we would be able to notice and correct the mistakes that hurt the functionality of our mechanical model. The biggest of these corrections was the correction in size of the pieces. Being able to hold the pieces in our hands and see how they fit together, it became clear to us that we needed more layers for mostly all the pieces for the model to work. In addition to this, we noticed the space that would be required for the crank axle, so we had to adjust the spacing of the different keys to make sure they didn’t interfere with each other.
Iterations of Prototype: More Precision with Component Design
At this point, we felt confident enough to begin replacing cardboard pieces with wood pieces. We were slowly able to add wood parts until we had a piano model entirely created from wood. We found that this iteration of the model did not work nearly as well as we would have liked, with each crank seeming to only have about a 20% chance of success. The ‘key pushers’ would jam with almost every crank and, despite using baby powder and sanding, required a ton of effort to complete a full revolution. It was at this time that we met with the class to present our progress, and, after some insightful comments from Dr. Wettergreen, we were able to identify 3 big problem areas that needed to be addressed.
- The ‘key pushers’ and side supports needed to be redesigned in the form of a finger-joint box. Originally, the designs called for layering the same pieces on top of each other, but this hurt the accuracy of the part as we had to drill holes into them instead of drawing holes. With new pieces in the form of a finger-joint box, the holes were able to be sketched in Adobe Illustrator, which removed any possible human error from the equation.
- The ‘figure 8s’. Although functionally these pieces worked well, they simply weren’t accurate enough as we had to guesstimate at which angle the piece should go to create the wave-like motion we wanted. From this, we decided to create a second version of the ‘figure 8s’. These parts had 2 holes specifically for accuracy, as inserting rods allowed for the pieces to be glued at the desired angle with, once again, no human error involved.
- Reducing likelihood of ‘key-pushers’ jamming. We noticed that the top base layer was very thin and sharp, which made it very difficult for the ‘key-pushers’ to move uniformly. In order to counteract this, we laser cut a box of indeterminate size. We were able to glue this box around the ‘key-pushers’ to keep them aligned and to stop them from coming into contact with sharp edges. Thankfully, this was able to fix the problem.
After these adjustments, we tested motion with one key first: One key test
Then we added the rest of the components and tested motion: Full set
Post-Processing: Black Keys and Clear Coat
The final step before finishing the model was post-processing. This mainly consisted of sanding down the model to a smooth finish and making sure that the keys did not catch when cranking. We also did some extra post-processing work on the piano keys by painting them. Initially, we wanted to paint the piano in the traditional black and white colors, but we weren’t able to find any white paint. Because of this, we clear-coated the piano keys which are usually white. Also, we made sure to only clear coat the piano keys as we still wanted some distinction in color between the keys and the rest of the mechanical model. We initially thought of using black wood stain for the black keys, but it wasn’t as dark as we thought so we switched to black spray paint.
Cost Analysis: $761.98!
Labor: 2 people x ($7.25/hr / person) x 50 hours = $725
Laser Cut:
Wood: $35 for one sheet of wood
Laser Cutter Machine costs: 3 hours x ($0.12/1 hour) = $0.36
Water Jet Cut:
Aluminum: 4 in^2 x ($44.68/288 in^2) = $0.62
Water Jet Machine costs: 2 minutes x ($30/60 minutes) = $1
Total Cost= $761.98. Relatively cheap for a piano!
Conclusion
We are very happy with how our piano model turned out. We were able to make the movement of the components smoother than expected. There were some areas in which we could have done better. For example, the model itself is slightly misaligned, which is very easily noticed when looking at it from a top down perspective. In spite of this, we felt that the function of the model was great and had a lot of making our vision into reality.
Video of working model: https://drive.google.com/file/d/1tn27piXHZ1S_ybQwtWMW7KbcHzvlDvuq/view?usp=sharing
2D file: Piano File with Majority of Components
