This in in addition to my dual drive remix. See my profile.
I found that the spindle skips out of the gears. I wanted to make something that would lock it in. This is lined up perfectly with the hexagon opening on the spindle gear. The 608 bearing is pressfit in place. The hex shaped pin sized to easily slip in pace without any friction.
I used the idea to run M6x50 bolts through in stead of pins for extra stabilization.
Now it can never skip out of place when respooling your filament!.
Here is a short video of it working:
https://photos.app.goo.gl/nj3xwZkRHdbWedXH8