My original idea for the electronic drum triggers used piezo pickups and allowed the user to set each drum to a specific note and alter the note by using some type of sensor, potentially a touch sensor. The first sketch I made had 11 triggers in total and would be as large as 20" in diameter and were individual pads that could rest on a table or on an acoustic set. I soon realized that 11 triggers would be an unreasonable task for the two weeks I had to complete the project. So, I decided to only include a 4 piece set (snare, 2 toms, bass drum) and also include a hi-hat and a ride. I then made a prototype of a trigger using 3 layers of foam core. The first layer was a backing, the second had space to house wires and a piezo pickup, the third had a space for a touch sensor (preferably analog). When we pitched our ideas to Saeed and our coaches, they recommended that the instrument be attached to the users body. While planning to create a piece of hardware that could attach to the user, I decided to scale the size of the pads down to 5" for the snare and ride, and 3" for the hi-hat and tom.
From the beginning, I knew that I wanted to use some sort of rubber as the head of the drum. The challenge was finding a conventionally available type of rubber that was responsive enough and would give enough fo a rebound to be a drum trigger. I decided to use linoleum as the head of the drum. After making 4 prototypes out of paper, I decided to lazer cut the final version of the linoleum (for the heads) and HDPE (for the part that attaches to the user's leg. I then use epoxy to connect the HDPE to the linoleum. After days of waiting for the epoxy to dry, it never lost it's sticky and gooey consistency. I was later told by David that the reason for the epoxy not curing was because HDPE is designed to prevent liquids from sticking to it. That is why the material is used for milk jugs, so the proteins in the milk don't condense on the inside of the container. However, I learned this right before the day of the presentation so it was too late for me to make any changes. Another problem I had was, while making a hole for the piezo to fit in, was I drilled right through the linoleum because it was so soft. This happened even while applying minimal pressure to the drill. So, I just decided to drill through all of the heads. I then printed acrylic heads to cover the holes. The piezos would now be glued onto the the side of the hole so that the sensitive portion of the pickup would be able to move freely and touch the backside of the acrylic.
Another time consuming aspect to my project was wiring all of the sensors to the Arduino. At this point, I had settled on all of my sensors, 4 piezo pickups (for snare, tom, hi-hat top, ride), 1 cap. touch sensor (to change pitch) and two touch sensors (for bass drum and hi-hat pedal). When the piezos arrived at the NuVu studio, I spent most of a day soldering the wires to the sensors. One thing I learned while wiring was to not use heat shrink as bundling. Using the heat shrink for bundling made it difficult to find the location that the wires ran to and create more work for me after finishing the wiring. Finally, After finishing the wiring, I was able to sew spandex straps with velcro. I also put the Arduino and wiring into a wood case I made on the laser cutter. I also epoxied the 9V battery pack onto the outside of the box. However, the final product did not work because I was not able to get adequate sensors that could get a consistent reading when triggered. Although the sensors did not output consistent readings, the programming on Max MSP did work properly.