CNC conversion Questions and Linuxcnc

The Hostmot2 manual page describes the firmware used with LinuxCNC
The filter options are all controlled by setting parameters in LinuxCNCs hal file

Thanks, that gives me s better idea of how things are interconnected.
Still trying to figure out specifics for encoder. I could make an aluminum or plastic wheel with notches and put behind spindle pulley, for lathe but how many notches? And do i need quadrature? Index pulse? does lcnc need direction and acceleration feedback for CSS and threading etc?

You need quadrature only if you reverse the spindle during spindle synchronized motion (for rigid tapping etc)

You need index for any spindle synchronized moves (threading etc)

Theoretically you could get away without index with a clever hal component but you
would end up with a volatile index position so could not resume threading etc after a shutdown

Required encoder resolution depends on spindle speed regulation and how slow you need to go
Poor speed regulation or slow speeds require higher encoder resolution

Even a single pulse per revolution will work if the spindle speed variation per turn is small
(large spindle mass, small load variation etc)