Wednesday, January 13, 2010

Chainsaw Sharpening Tips

This ad was in a little farm newspaper that we get in our mail every week, and I think it is safe to assume that many chainsaw owners believe the statement that chains can be sharpened "4-5 times," and that they are willing to pay $10.00 to have a chain sharpened for a twenty inch bar. That is a pretty good gig if you can get it, but when you figure that the saw owner is going to be paying $50 to sharpen a $15 dollar chain into oblivion, and will be cutting with a dull saw most of the time, it makes me cringe. When you buy a couple new chains for your saw, buy a box of files, a sharpening jig that will work on your saw, and take the time to learn how to sharpen. It's easy, and we will go over the basics for you.

Out in front on each tooth is the depth gauge. You will hear it called the raker, but it's real purpose is to control the thickness of wood that the tooth can bite. As you file the tooth back the depth gauge must also be filed down to match it. You don't have to file the depth gauges every time you sharpen, and I do them only on the workbench, not in the woods. The parts of your tooth that you work with as you file are the depth gauge, the top plate, the side plate, the top angle, and the side angle. As you look at the teeth above, mentally draw a line 90 degrees down from the front edge of the top plate. That line should evenly intersect the arc on the front of the side plate. If the arc is hooked forward the tooth will bite more aggressively, and if the arc is leaning back the tooth will not bite hard enough. When the side angle is correct, the angle of the edge under the front of the top plate will be very close to 45 degrees.
You can see that the third tooth in the photo above is filed so the tooth will be lazy. This can be straightened out with a filing jig, or by providing a little downward pressure in the gullet as you file freehand.


I believe in filing every time I fill the fuel and oil tanks on my saw. These teeth have cut through one filling, and you can see a little bright edge on both teeth, plus an obvious bright spot on one tooth. This is how you know whether your chain is sharp or dull. The top should disappear at the front edge with no bright spots or edge. Usually you will be able to find some bright edges after each tank of fuel, so a fillup is a chance to keep your saw sharp.


Point the teeth into the light, put on your reading glasses, and the need to file becomes obvious.


Adjust the slack out of your chain, block up the bar and look for the dullest tooth. Check the gullet on the sideplate to see if you should press straight back, or slightly up or down, and push your file through with a straight stroke at the 25 to 35 degree angle of the front edge of the top plate. Use a file handle so you can make strokes the entire length of the file, and count the strokes needed to remove all of the bright edge. Advance the chain and repeat all of the way around the chain, then turn your saw around and do the other side.


The Carlton File-O-Plate is an easy jig to use to correct your angles if you use Carlton or Woodland Pro chain. It keeps your file at the right depth, and shows you the correct angle for the top plate.


This little tool is hard enough that files barely mark it, and you can use one for years. I usually file freehand in the woods because I am afraid of losing it, but I use it at home to straighten things out.

Look closely and you can see a depth gauge peeking up through the little slot. I like to file the depth gauges after I have rehabbed the saw at the end of the day, and the File-O-Plate system seems to set them right for cutting oaks and hickories.


This little gizmo is common in lots of chainsaw departments. I picked this one up at Lowe's in a Husqvarna blister pack, and the chains hanging nearby were Oregons. I set it on my Carlton chain, and it held the file a bit high. The good news here is that the slots can be filed a bit deeper so the rollers will hold the file in the sweet spot for you. This tool also has a gauge for filing your depth gauges, with two choices for the type of trees you are cutting. This is an easy tool to use, and most people who try it like it.

I think this little stamped guide is sold in every saw shop in the country, and it's not a bad tool to have in your kit. It shows you the correct angle for the front of the top plate, but it is not hard metal, so you have to be mindful of your side angle, and aim your pressure appropriately. If you bear downward, you will soon have the slot deepened, and you will be filing your gullets too low, making the teeth bite too aggressively.


This file guide has two slots for filing your depth gauges; one is .030", and the other is .035".
Use the right one for your chain and the type of wood you are cutting. I tried the .035" slot on my saw with a .325 chain, and it made the teeth too grabby to use in hickory. It still worked OK in oak, but that was a good lesson about pushing the limits. The .035" works fine on my saws with .375 chains.

The end of this tool is very useful for cleaning sawdust and gunk out of the rail on you saw's bar, so whether you sharpen with this jig or not, you will want to have one in your kit.


Once you understand what the tooth needs, you will be able to file freehand at every fillup so you always have a sharp saw. If you tag a rock, or other hard object, stop the saw right then and inspect every tooth. You may only have one or two dull ones, and you can fix it right then so you keep throwing chips instead of sawdust. Now, let's watch a logger touch up his saw during a fuel break. There is a mildly amusing story told by the skidder driver, so turn up the volume.

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