Sharpen a chainsaw chain when its cutting behavior changes—not after an arbitrary number of cuts, fuel tanks, or hours. A chain that produces coarse chips, feeds into sound wood without being forced, and tracks straight may not need filing. Stop and inspect it when the chips turn dusty, feed pressure rises, the cut slows, or the saw starts pulling or vibrating differently.
A chainsaw chain that dulls quickly is usually touching abrasive material, leaving the sharpener with a weak or incomplete edge, or running with poor lubrication or an incorrect setup. Do not sharpen it again until you identify which one. Repeatedly removing metal may hide the evidence and shorten a chain that was not the original problem. Start with the last few cuts. Soil on the underside of a log, gritty bark, a stone, or hidden metal can round a fresh edge in seconds. If the cutting path was clean, move to the cutter shape, oil delivery, tension, guide bar, and the chain’s remaining condition.