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If you can turn up the D-bit on the lathe and cut it to an accurate 1/2 distance, provide the backing off etc, then a fine hand whetstone will enable you to get a suitable smooth finish on its cutting edge.When lapping rather than using a "dry sticky lump" (iron oxide combined in tallow or the like) which is what buffing mop polishing compounds are, you need your abrasive suspended in a fluid. You also need to be able to clean it off regularly and put on some new abrasive and oil. I was thinking car paint cutting compound or possibly a household abrasive surface cleaner for the final polish. Jo P.S. If you try using a buffing mop compound it is worth knowing they clean off with hot soapy water and not the sort of things you would use to clean up oil based residue.