October 11, 2018
The junk shelf has been my muse throughout Intro to Fabrication. I like the challenge and constraints that come from upcycling random, discarded items. This past week’s assignment to build a motor mount was no different. Inspired by an electric razor I found on the junk shelf, I fabricated the physical component to my Intro to Physical Computing Halloween midterm project — a game about ”ghosting.”
It started with a working Taurus electric razor (not sure if the blades could still cut facial hair, but the device still turned on and vibrated). I opened it up and found inside the razor a 1.2V DC motor and a plastic horn that transformed the motor’s circular motion into a vibration motion. Some dust and old hair cleaning was required…
Once I had broken down the razor into its components, I confirmed the DC motor could run off of a AA battery’s power by connecting it to a simple circuit with a battery (video). Next, I composed a circuit that used a transistor and an Arduino’s digital pin to trigger the DC motor (more details to come in the Intro to Physical Computing blog post, video testing transistor circuit).
I then did a rough sketch and cardboard prototype of the phone panel I wanted to vibrate using the razor’s motor (video). I opted to also reuse the razor’s top case because it had an internal plastic frame that stabilized the motor and provided structure for the plastic horn top to vibrate.
The motor proved strong enough to vibrate my first cardboard phone panel, but I wanted to see if the vibration effect appeared like the typical vibrating smartphone. So I used the laser cutter to create a phone screen of a ghosted conversation. Unfortunately, I used cardboard that wasn’t completely flat, so the laser ran into part of the cardboard during the cutting stage, resulting in the material shifting on the stage and cutting in unintended places. Also, a 5 pound weight from the junk shelf was taped to the entire mount to give it some weight and prevent the whole mount from vibrating.
Satisfied with the cardboard phone screen and the vibrating effect, I proceeded to laser cut the phone screen into a 1/8 in plywood (the same wood used in the sumo sound project). Here is a video of the first wooden prototype.
A quick trip to KMart led to a Halloween cauldron that would eventually enclose the motor mount. A quick test ensured the 5 pound weight could fit in the plastic cauldron.
I then tested fastening a wooden platform to the weight using a bolt, nut, and wooden scraps from the shop. The first bolt I used was long enough to comfortably pass through the wooden and weight layers, but I realized it’s square neck couldn’t fit through any nuts I had. So I ended up using a bolt that was just long enough to have a nut screwed on. I also upgraded the wooden scraps to laser cut circular wooden panels that would distribute the pressure over a greater surface area and provide more space to attach the motor mount.
The following step was to figure out how to attach the motor mount to the five pound weight and where the hole should be on the plastic cauldron for the razor to stick out of. I used the razor’s bottom half as my hole test piece and drill test piece since it was made of the same plastic material as the razor top motor holder. My plan was to drill holes through the razor top and attach it to the weight’s wooden platform using wood screws.
It surprised me how well the razor’s plastic drilled through. I then repeated the drilling process on the razor top that held the motor and plastic horn. Here is a video of the enclosed prototype.
Gaffer tape was used to attach the phone screen to the plastic horn in all of the previous prototypes. But I wanted to create a more permanent bond, so I referenced this to that for the type of glue I should use to attach plastic to wood. It recommended Goop, which I found at the local M&D Shapiro True Value Hardware store. I sanded down the wood and plastic to create slightly rough surfaces for a better adhesion setup and tested a Goop glue job on spare wood and plastic horn piece from the razor. The test job went well, so I applied it to my final phone screen and plastic horn and clamped the two together overnight.
The next day, I undid the clamp and tested the phone/plastic horn attachment. There was a slight hiccup because I had allowed the glue to fill the gaps in the horn that originally attached to plastic teeth on the razor. This caused the phone to swivel on the horn…
So I cheated a bit and used gaffer tape again to prevent the phone from rotating on the plastic horn.
Here is a video of the final working motor mount that will eventually be driven over serial communication by a website.
NYU ITP documentation blog.
Words are my own.