Simple jig made from scraps to sharpen chisels.
I used 180 and 500 grit for the sanding disk and it does the job.
The bearing ensures flatness since the disks stand on it's race. The spring just helps holding the preload on all the parts to transmit the torque and keep it flat
Please keep in mind I have no idea of sharpening chisels :D

Part 2: Testing on a cheap chisel:    • DIY Drillpress sharpening jig  (Part 2)