One Micron Mechanism
May 2024
Stanford, CA
As part of the coursework from Precision Engineering (ME324), my teammate and I designed a turntable-style air bearing where the graphite insert serves as both thrust and journal, using gravity as a preload. We designed and fabricated the tolerance between the disc and graphite to be around 5µm.
Unlike conventional designs, we reversed the typical positive extrusion of the journal, integrating both thrust and journal surfaces into the graphite insert.
The resulting air bearing achieved spin times of over five minutes. Some visible runout remains due to the aluminum disc's exterior not being machined to tight circular tolerances.
Iteration 1 — CAD
Proof-of-concept design that illustrates the interactions among the base (green), graphite (yellow), and disc (orange).
Iteration 1 — Fabrication
Learned that the initial materials we chose don’t adhere properly, resulting in the graphite insert popping out upon running compressed air.
Iteartion 2 — Fabrication
The epoxy successfully secured the graphite in the base after we changed it to aluminum, and we confirmed air escapes through the pores of the graphite by submerging in water.
Iteration 2 — Testing
Learned our concept works to an extent. However, the small scale and some other factors resulted in an unstable air bearing.
Itaration 3 — Design
Redesigned the previous iteration to be larger, increasing surface area of graphite and increasing the gravity preload for more stability.
Iteration 3 — Testing
Increasing the scale and preload significantly improved rotational stability over the previous iteration. However, the aluminum disc was machined slightly off-center, resulting in visible runout.
Final Iteration Working Video
As shown in the video, our final air-bearing can rotate for more than 5 minutes after a gentle actuation by hand.
Final Iteration Photos