A chain saw is an amazingly efficient, high-speed wood cutting device. When properly maintained and properly operated, a chain saw can make short work of some very big jobs. If you notice your chain saw is not cutting in a straight line, or the chain jumps and chatters at you, or you are getting sawdust when you used to get wood chips, its time to sharpen the chain. Everyone knows a sharp chain cuts better than a dull chain. But an improperly sharpened chain is little better than a dull chain. It's all about the angles.
No chain saw, regardless of how powerful it may be, can work efficiently unless it is properly maintained, and that means applying the correct angles when sharpening the blade. Improper angles can result in great effort being applied to the task, putting undue strain on the chain saw. This can ruin the bar and damage the sprocket and internal engine parts. Improper sharpening angles can even result in safety hazards from kickback.
Chainsaw chain sharpening angles are precision designed to allow specific chain saws to operate at peak efficiency. The sharpening angle is determined by the pitch, the drive link gauge and the chain length. In addition the chain saw may be designed with a chipper chain with a curved working corner that will help it maintain its sharp edge longer, or a chisel chain with an angled working corner which helps it to cut faster. The sharpening angle works in conjunction with all other routine maintenance functions to keep the saw in best cutting condition.
Each specific type of chain requires a specific file size, file gauge and angle guide. A rule of thumb is to use 85 degrees for a Micro cutter (chains labeled RM, PM, PMN), 60 degrees for Super cutter (chains labeled RS)and 80 degrees for special ripping chain. Because saws, chains, and sharpening angles differ significantly between manufacturers and models always consult your owner's manual or manufacturer's website to obtain the correct sharpening angle.
Attempting to cut with a dull chain puts undue stress on the chain saw resulting in higher fuel consumption, loss of power, and excessive wear and tear on the unit. Sharpening the chain to the proper angle will improve the chain saw's efficiency and increase the life of the tool. Even the most seasoned lumberjack can only give a best estimate when it comes to sharpening angles, so most manufacturers recommend taking the chain saw into an authorized shop for professional sharpening after you have sharpened it yourself 5 times.
Even when dull the cutting links on a chain saw chain can be sharp enough to inflict a wicked cut on human flesh. Never handle a chain saw chain without first putting on a pair of heavy duty gloves. Never handle the chain while the chain saw engine is running. When sharpening the chain in the field after operating the chain saw, the unit will be hot. Avoid contact with the exhaust muffler to prevent painful burns.