Fox Factory Bearing Assembly Rundown and Torque Automation Project

A machine design was created to partially automate the rundown and torque of a Fox Factory shock bearing housing. This machine is needed at the factory to keep line associates safe by reducing ergonomic strains associated with this stage in the shock assembly process. Due to the lack of applicable torque drivers for this operation, an open ended, geared drivetrain was designed to allow for engagement of the bearing housing while allowing clearance for the shock shaft that the bearing rides on. This open drivetrain is held by a structure of linear rails and bearings to allow the line associate to guide the open gear into place on the bearing. A pneumatic cylinder and several rail brakes will be used to press the bearing housing into the shock body tube while beginning the rundown process. A control system consisting of a PLC, HMI, and torque driver controller was designed in terms of wiring & programming to control torque and pneumatic outputs. At each stage in the design process, safety and ergonomics were considered so the machine would satisfy the first and second design principle for the Fox manufacturing engineering department: safety and quality, respectively. Basic analysis for component strength and stiffness was performed where any concerns were present, and a maintenance schedule was created for any potential wear items. While the original intent was to manufacture and assemble nearly all machine components in house, parts were instead outsourced by Fox due to various factors stemming from the COVID-19 pandemic

Performance and characterization of the SPT-3G digital frequency-domain multiplexed readout system using an improved noise and crosstalk model

The third-generation South Pole Telescope camera (SPT-3G) improves upon its predecessor (SPTpol) by an order of magnitude increase in detectors on the focal plane. The technology used to read out and control these detectors, digital frequency-domain multiplexing (DfMUX), is conceptually the same as used for SPTpol, but extended to accommodate more detectors. A nearly 5× expansion in the readout operating bandwidth has enabled the use of this large focal plane, and SPT-3G performance meets the forecasting targets relevant to its science objectives. However, the electrical dynamics of the higher-bandwidth readout differ from predictions based on models of the SPTpol system due to the higher frequencies used and parasitic impedances associated with new cryogenic electronic architecture. To address this, we present an updated derivation for electrical crosstalk in higher-bandwidth DfMUX systems and identify two previously uncharacterized contributions to readout noise, which become dominant at high bias frequency. The updated crosstalk and noise models successfully describe the measured crosstalk and readout noise performance of SPT-3G. These results also suggest specific changes to warm electronics component values, wire-harness properties, and SQUID parameters, to improve the readout system for future experiments using DfMUX, such as the LiteBIRD space telescope