In the picture You see the head drum I used, already fitted with a short steel tube fixed on the shaf.
I used a little postscript file to create my disk. THIS is exactly the disk I’ve printed, the original file comes from the now dead link http://epl.harvard.edu/Engineering/encoderdisk.html and allows to print disks of any size and resolution. You must print the disk on a laser or inkjet transparent sheet.
This system allows to change speed and resolution of the spinner just by printing another disk.
If you have an old laser or inkjet printer, and the black ink is too transparent, print 2 or 3 copies of the disk and glue them together.
And this is the full assembly: flywheel + encoder disk + mouse PCB + cable. It’ll never works! :-)
Just kidding! It worked at the very first time!!! The only problem is that, to test the spinner, I played Arkanoid all the night and now I’m reeeeally tiiiiiired :D
I’ve also glued in a better way the PCB to the metal support.