Thank you for the link Buzzer, and for the excellent inspiration.
The kit you linked to will work very nicely indeed on my lovely old planer from an era before stepper motors and DROs.. The holy grail of repeatable settings. I could use 5 on my tenoner or could manage with 4. It will be the envy of chippies for many a country mile..
I had to grit my teeth a bit though.. Somebody is listing their kit as a digital Vernier!!