Sharpening of Chainsaws


Fall is traditionally firewood cutting time, and with the high cost of fuel oil, it looks like we all will be cutting more wood this year. To get the most from your chain saw the cutting chain needs to be very sharp. Using your saw should be a case of guiding rather than pushing the saw. If the saw is not easily cutting through a log with minimum effort by the operator then the chain is dull. This may happen quite quickly or take up to an hour of wood cutting, depending on conditions.


There are several components to the cutting chain. The following illustrations will reference these parts and the terms used to describe them. This will help you understand where to concentrate for chain sharpness.


The side plate and top plate edges are the portions of the chain that require sharpening. The depth gauge setting is the distance (in thousandths of an inch) between the top of the depth gauge and leading edge of top plate. This determines the thickness of chip each cutter is pulling from the log. Notice that the cutter is tapered back along the top plate and as you file away material the depth gauge setting will be reduced. Therefore it is necessary to file the depth gauge down after 3-4 sharpening of the chain. This procedure is done using a depth gauge tool and 6" flat file with no edge cut. We will address with this later.


Sharpening The Chain


The following angles and settings are for small to medium (30cc to 60cc) saws cutting woods that are commonly used for firewood. If your cutting needs are outside of this you should consult a professional chain saw dealer for further advice.


The correct size round file should be selected from the chart below. (These files can be purchased at our website in the closeouts section or most hardware or lawn and garden equipment stores) Also your owner's manual will probably tell you.


Place the file into the cutter, which has the most wear or damage. (L/H cutter or R/H cutter); scan the chain visually to determine this. Follow the illustration as shown below, filing on the push stroke direction only. The drawback stroke of the file should barely touch the cutter. Position the file to a top plate angle of 30°. 1/10 of the diameter should be above the leading edge of the top plate. This will give you the correct side plate configuration (approx. 15° back slope) and top plate edge angle (60°). Hold the file on a horizontal plane (90° to the bar).


Continue filing until the edge of the side and top plates are keenly defined with the profile of the cutter. You do not want any burred or rounded edges here. The cutter is then sharp. Important- Count the number of filing strokes to bring the cutter to this condition as you will need to apply the same number of strokes to each cutter ensuring uniform length. Move to the next cutter of the same hand (next R/H cutter if you started with right or L/H if beginning with left) and file in the same manner using same number of strokes. Continue filing all cutters of that hand until all are sharpened.


To file the opposite hand cutters it will be necessary to move to the other side of the saw. Begin filing using a like number of strokes. You will find that most people are either right or left handed so filing one side will be easier than the opposite hand. For this reason you will want to take greater care with your least dominant side to ensure uniformity. Important- when filing you do not want to apply downward pressure on the file. This will tend to only file the bottom of the cutter (which will do no good if you want to cut wood). You should apply pressure sideways into the cutter which will accentuate the sharpening of side and top plates (which actually do the wood cutting). If your chain is very dull it is probably best to have it sharpened at a repair shop, they should have an electric grinder to do the job quickly and can also set the depth gauges.


Filing (setting) depth gauges You should purchase a depth gauge file and a tool with a .025" (0.65mm) or .030" (0.80mm) value ( .025" for most applications, .030" for softer green wood). Remember the higher the setting value, the more aggressive your saw will cut into the wood. You should not go above these numbers or the chain will bite into the wood and stall. It will also be very difficult to hold the saw back to prevent this condition, and clutch damage will probably result Lay the depth gauge tool over the chain as shown below and the depth gauge will protrude from the slot. Again, it is easier to file toward the outside of the cutter so do one hand first then reverse dies to complete the other hand. This will reduce the filing chatter. When the file comes into contact with the hardened flat surface of the tool (after filing down the protrusion of the depth gauge) the setting will be correct.


On some chains the radius on the front of the depth gauge is abrupt and after filing down a few times you will want to round off this edge to continue smooth entry for the cutter into the wood.


Other helpful bar and chain tips Remember it is better to touch up your chain a little more often, than to leave it until it is very dull. If you adhere to this practice it will only take 5-6 strokes to bring the cutter back to sharpness. This means sharpening on the job site. If you want an easy way to hold your saw on the job try cutting a few inches into a log or stump. This will hold the saw bar nicely and prevent it from skidding around. Now you can use both hands to hold onto the file.


Every 6-8 sharpening's take the bar and chain completely off the saw and clean out sawdust and dirt build-up in the bar groove and oiler hole. When re-installing the bar, if it is reversible (most are), turn it over to maintain even wear on the bar rails. If you are getting a burring or rolling edge on the bar rails you are running too long on a dull chain - sharpen more often! Most bars are sprocket tipped and should be run with the chain having no slack from the underside.


Remember to wear gloves and carefully pull the chain around the bar (from the top side pull forward away from the power head) to be sure there is no binding. The chain should roll easily around the bar. -Make sure the chain brake (if equipped) is disengaged with doing this -Never touch the chain under ANY circumstances when the engine is running or if electric, the power cord disconnected -Use proper bar and chain lube grades to suit the season/temperature. If you have filed the cutters to about 1/6 of their original length and the frame (other articulated components) is still in good shape, don't feel cheated that you haven't gotten full life out of it.


Quite the contrary - you have done a good job in maintaining a sharp chain resulting in less stress on the clutch, bar, sprocket and yourself. The cutter filed back to this amount with a good frame is what you are striving for. So smile knowing you have increased you chainsaw's life by sharpening regularly.