The Crescent Nicholson round knurl-cut chainsaw file with an American pattern. For ideal results, place file against beveled cutting surface of the teeth 20° to 45° with saw and file from the inside to the outside of cutter. Sharpen all left-hand cutters on one side of the chain and move to the other side and file all the right-hand cutters. The height between cutting teeth and depth gauge is between .020" to .030" — check the depth gauge height every 2 or 3 sharpening's. Tighten the tension on chain to firmly support cutters when filing.