a few weeks ago I put a cheap mighty might fretless neck on my mim 60s jazz to see if I likes it before I invested in a bass or a defret. loved the sound but the fingerboard was like a ruffles chip so it buzzed like crazy even with high action some notes were nearly unplayable.last night i took it off and spend a few hours sanding it with a radius block. 280grit then 1000 then 2000. it was grey after as i have read about so i polished it with a rag and a dab of tung oil. it looks better than it did before i did the job and i was able to get it down to 2mm at the 12th without any buzzing at all.