Also when filing, the filing guide should be held at a 90-degree angle to the bar or level, tilting the filing guide even slightly can result in the misfiled chain that won't function properly. On the top of your filing guide, you'll see lines inscribed into the metal. The lines kept parallel to the guide bar when sharpening each tooth will result in the proper angle required for the tooth's cutting edge when used properly. Your filing guide will help assure a proper and consistent cutting angle and filing depth on each tooth. This is how a properly sharpened cutter should look. Here is a cutter that has been improperly filed and has a severe back slope, a sign possibly indicating that too large a file was used. This chain has a severe hook indicating that too small a round file was used or that the file was pushed down too hard and allowed to drop too far down into the tooth during the filing process. Here you see a top plate with too shallow of an angle and this is a top plate with too severe an angle.
Now that you have the proper filing guide have determined your starting point, begin your filing. Remember to count your strokes, the amount of pressure you are applying to file and do not drag your file back across the cutter. The right and left hand cutters alternate so you will need to file every other tooth from one side of the bar or all of the right hand cutters first for instance. Then change to the other side to sharpen all the left hand cutters again, remembering to keep the angle and depth the same on all teeth.
Once all of your cutters have been sharpened on both sides, you will need to check the depth gauge's height and file down the tang if needed. Place the depth gauge tool on the chain, as shown here, allowing the tooth's depth gauge to protrude in the slot of the tool. If any portion of the depth gauge protrudes above the slot of the tool that portion will need to be filed down level with the depth gauge tool using the flat file. Perform this same procedure for every tooth. If the depth gauges are not maintained and are too high, not allowing enough clearance, this will result in poor performance and result the chain's ability to cut. If you didn't use the proper depth gauge tool and filed the depth gauges too low, below the manufacturers specifications, this will results in a chain that cuts too aggressively, possible causing harm to your saw and increasing the risk of backlash, making the chainsaw very unsafe, which can result in a serious or fatal injury to the operator.
If you have filed your chain's depth gauge several times, you may find the leading edge of the depth gauge will need to be dressed to conform to an angle similar to how it looked when it was new. Stihl depth gauges have a line scribed into the metal showing the proper angle for the leading edge for you to follow. If you don't maintain this angle, it can result in excessive vibrations when cutting as well as diluting the low kickback properties on some chains.
For some people, sharpening a chain is uncomfortable or even intimidating. If this is the case with you, you might want to keep one or more spare chains that are properly sharpened with your while you are working on your chainsaw. As your chain becomes dull, you can easily replace the dull chain with one of your spares.
When you are done with your work, return your dull chain to your authorized dealer where they can be properly sharpened on specially designed on an electric chain grinder and you will be ready to cut again with a set of freshly sharpened chains.
Next, check your chain brake to make sure it is functioning properly and that it engages and disengages. Like an automobile brake, your chainsaw's chain brake will incur wear each time it is engaged. The amount of wear will vary depending on things such as usage or even the conditions in which the saw is used. Excessive wear will reduce the effectiveness of the chain brake and can ultimately render it inoperable.
Begin your own inspection; you should always turn your chainsaw into your authorized dealer to have the chain brake inspected according to the schedule form in your manual. With the engine running at idle, engage the chain brake by moving your left wrist forward while gripping the handle then accelerate the engine to full throttle for no more than about 30 seconds before premature wear to the braking system or harm to the engine. The chainsaw must not rotate. If the chain brake fails to function properly, it's imperative that you take your chainsaw to an authorized dealer for the proper repairs prior to using your chainsaw again.