Alrighty then, Christmas and New Year out of the way, back to work.
I've been rethinking the design of the control column mechanism, specifically the self centering . It's overly complicated for something that it is relatively straightforward. Taking cues from what others have done, I'm now experimenting with a simple "pull me, push you" approach.
First step was to saw off the end of the screen door closing mechanism and to put a thread on the rod:
The thread allows ease of adjustment to get the control column center just where I want it. Next I made a simple bracket out of HDPE (High-density polyethylene, the stuff quality chopping boards are made of) to anchor the other end of the closer to the frame. HDPE machines very easily on my table saw and offers up a low friction surface:
With the closer attached to the swinging arm I tested the resistance. Feels about right but I won't know until I have it loaded with the control columns, yokes etc. The idea of this design is that when the arm swings towards the closer, the rod passes through the opening in the swing arm. When it goes in the other direction, the end of the rod engages and pulls the arm back to center: