Spindle liner

Chip breaking is not the forte of insert tooling on non metallics. A honed HSS and a bit of corner radius would do the trick, not to mention better feedrate.
We don't make long spindle liners. A pair is a better choice, though can be made as one and parted in two, with generous entrance chamfers. An over-square proportion works best, longer than diameter, including increased vibration damping. Finally, a pair is more tolerant of residue in the spindle.
Mark them with felt tip pen and store tied together, they last a long time.

Spindle liner - video