"Bob S" wrote in message

However, it may be that no knurling tool is going to work well as
the
last step on a filter ring because the ring is thin and will bend
under the load. Maybe I need to knurl first and then bore out the
center.
Bob

If you can index and lock the spindle you could manually shave
gripping grooves in the OD of a ring with an appropriately ground
lathe bit in the tool holder. Don't expect to take more than a few
thousandths off per pass.

The carriages on lathes I've tried it on had to be held down against
the ways with one hand while I cranked them toward the headstock to
shave off the chips.

jsw