Udate on the $3 sparkfun encoders........
Long story short, they work on Ikari Warriors (which I did all my testing with) but for some reason won't even register when mapping controls on Heavy Barrel and Victory road.
Pretty sure it's caused by the super low resolution since I swapped in a 900 line encoder and it registed immediately using the same inputs on the same Opti-Wiz. It would have been an awesome cheap solution if they'd worked out.
Anyways, here's the setup I came up with for others venturing down this path.
To join the joystick shaft to the encoder, I ordered a set of these 6mm shaft couplers off fleabay:
These were going on Seimitsu LS-56 joysticks which have 6mm (1/4) shafts.
Since the joystick shaft was the same size as the encoder shaft, I decided to cut it down to save height.
Here are my parts:
Optical encoder, post made by hammering aluminum rod into an aluminum base, yoke cut from 1/4" abs plastic, & the coupler.
I made the slot in the yoke 1/4" wide thinking any wiggle room would result in an unwanted dead zone. This line of thinking was off.
It needs some wiggle room, or at least a thinner yoke, because it will bind when the joystick is at an angle.
This binding combined with the inside of the yoke not being perfectly smooth resulted in a grinding feeling being transmitted through the joystick.
If it weren't for that, I don't think it would have made the joystick feel noticeably different.
The tape on the pins of the encoder is because the motion of the joystick was causing them to make contact with each other.
The stiff wire I was using probably wasn't a good choice either, but this was just a test.
If I were to rebuild this using the same encoder, I'd extend the yoke a bit behind it and notch out a place to zip tie the wires to the yoke.
I was able to play Iraki Warriors and the stick tracks as it should, the guy moving in a 1:1 ratio with the stick.
I didn't like this so much and wanted him to turn faster.
I was able to get the coupler to fit a Sanwa JLF by widening the hole on one side with a drill press, but the coupler hits the tabs that hold the center piece of the restrictor in place. Although these couplers can be tightened down, they don't move very much at all, so the sizing has to be extremely accurate.
I'm disappointed. I really wanted these cheap little encoders to work.