The Crescent Nicholson round knurl-cut chainsaw file features an American pattern. For optimal results, position the file against the beveled cutting surface of the teeth at an angle of 20 degree - 45 degree relative to the saw and file from the inside to the outside of the cutter. Sharpen all left-hand cutters on one side of the chain, then proceed to the other side to file all right-hand cutters. The height difference between the cutting teeth and the depth gauge should be between 0.02 inches and 0.03 inches. Check the depth gauge height every two or three sharpening's. Ensure the chain tension is tightened to securely support the cutters during filing. American-pattern file featuring a knurled cut Adjust the chain tension to securely stabilize the cutters during the filing process Position the file at an angle of 20 degree to 45 degree against the beveled cutting surface of the saw teeth for optimal sharpening precision File from the interior to the exterior of the cutter Optimize the sharpening process by honing all left-hand cutters on one side of the chain, then transition to the opposite side to precisely file all right-hand cutters Verify the height of the depth gauge after every two or three sharpening sessions The height difference between the cutting teeth and the depth gauge should be maintained between 0.02 inches and 0.03 inches Adhere to the manufacturer's specifications to ensure safe usage