The Gong — Steven Trinh

THE GONG

Building a bi-stable toggle indicator

OVERVIEW: Designed a bi-stable toggle indicator that replicated the Stanford admit tradition of striking of the gong

TOOLS/SKILLS: Mechanical System Design, Rapid Prototyping, 3D Printing, Laser Cutting

TIMELINE: 4 weeks

TEAM: Tracy Lang

Challenge

We were tasked to create a bi-stable toggle indicator driven by a spring that carried out any function of our choosing.

We sought to pursue an idea that focused more on creating sound, like an indicator that can strike a gong.
We pursued the concept of hitting a gong, emulating the Stanford tradition of hitting the gong in celebration of admission into Stanford University during Admit Weekend. It’s an experience that many students here can relate to!

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Ideation

Sketching allowed us to get a sense of how this mechanism worked and how we want to incorporate it as a mechanism for a metronome. This mechanism is inspired by Spring toggle mechanism 3.

We applied the mechanism to this new gong design. In one position, the mallet is positioned away from the gong. In the next position, the mallet strikes the gong.

Rapid Prototyping

arbitrarily picked some dimensions that we thought would work for the bistable mechanismdowels and glue used to drive rotationsmall cardboard stoppers held dowels in place

CARDBOARD PROTOTYPES

overall prototype gave us a better understanding of the system of the mechanism and the function of each part
even without a spring, it oscillated smoothly
needed to remove the horizontal mechanical stop, since it did not actually serve its function

used foamcore and added in the spring component simplified our model by removing the unnecessary horizontal mechanical hardstop

FOAMCORE PROTOTYPES

smooth oscillation and robust bi-stable mechanism
small range of motion hurt functionality (hitting the gong)
need to scale up the size of the model to meet design constraints imposed by the project

Transitioning to a functional prototype

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LASER CUTTING

laser cutting provides a cheap means of fabrication
most parts made of duron to match gong aesthetic
the base (top left corner) would be made of acrylic for stylistic purposes and to accommodate for a heated threaded insert

3D PRINTING

handle drives bi-stable mechanism
press fit into acrylic base
3D printing (as opposed to laser cutting) allows for more design flexibility

Functional Prototype

prototype is functional, for the most part
significant wiggle room throughout the structure, resulting in instability during performance
the mallet would occasionally not strike the gong since it was too far away

Iterating

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REDESIGNING THE LEG

previously, this leg (held in the image above) was too thin, restricting the spring’s movement as it scraped against the two pieces of wood
increasing the thickness of the wood solves this

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ADDING A STAND

added a foot stand bolted down to the base to increase stability of the foot
removed the aforementioned wiggle room

Finishing Touches

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ADDING A BASE

designed our own gong stand and implemented it into a universal base

improving consistency, functionality, and aesthetic

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We decided that our prototype wasn't finished yet without having decorated it! This aspect of the product gave it life and sparks joy for users.

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