I am currently pursuing my Private Pilot’s License, training in Cessna’s 150/172.

I require hand controls to work the rudder pedals, so building off a rough CAD of the Union Hand Controls designed in the 1970s, I redesigned the setup for modern CNC machining, preserving the materials and some weld joints in order to (hopefully) facilitate FAA re-approval.

Stress analysis of the part shows that even with the mechanical advantage of the long lever, my 50lbf press on the end still results in a minimum safety factor of ~4 (the 240MPa is mostly a mesh artifact).

December 2020

This has been an exercise in designing for unknowns, since I don’t have a spec for force or translation required for full braking, the pedal geometry is similar but not exactly the same across multiple planes, and the pedal-well is hard to access for exact measurement!

To work with this uncertainty, I printed fixtures for handle and J-blocks to test positioning. When I was ready to begin welding, I printed a fixture for holding the T-joint, which you can see in-action below.

This was my first time TIG welding, and with Jared’s help and guidance, I loved how controllable the weld lines were.