Seismograph

A fully mechanical seismograph, built from raw stock to finished instrument. At its core is a suspended inertial mass that remains nearly stationary while the ground moves beneath it. The relative motion between the inertial mass and the instrument frame is mechanically amplified and recorded, converting subtle ground vibrations into a visible mechanical signal.

A critical design choice was the use of a knife-edge pivot system to suspend the inertial mass. Unlike conventional bearings, which introduce friction, backlash, and sensitivity limitations, a knife-edge pivot concentrates rotation along a precise contact line, allowing the mass to move with extremely low resistance while maintaining a well-defined axis of rotation.

This project touched almost every process in Stanford's Product Realization Lab: turning and milling, sand casting, oxy-acetylene welding, and waterjet cutting. The biggest challenge was maintaining the tight tolerances required to keep such a sensitive instrument aligned, balanced, and low friction.