Chainsaws

Side View

 
Top View

When chainsaws are sharpened using files, they are sharpened using a round file (sized for the chain). This is used to address the part marked in blue.

Oftentimes, a flat, mill file is also needed to reduce the size of the chip gauge (AKA, a “raker”). This is shown in the pictures marked in red.

Saw Type	Fleam	Drop	Rake	Chip Thickness	Comments
	A - Vise Rotate Angle	B - Down Angle	C - Head Tilt Angle	D - Depth Gauge
Crosscut
Round Ground Chisel tooth	25°	0° or 10°	55°	0.025” 65 mm	The drop angle is chain-dependent, but 10° is most common.
Chisel tooth	30°
Semi-chisel tooth	35°
Rip	10°	10°	50°	0.025” 65 mm

Notes:

1. When using the Oregon Products or Tecomec Bench Grinder, the term equivalencies for the Grind Angles Chart are shown in blue the table above. The Grind Angles Chart should also be consulted for the relevant angles, based on the chain you are sharpening.
2. These are some good general guidelines. Specific chains may require different angles.

Notes & Comments

Steps for Sharpening Saw Chains

Step			Comments
1		Clean the saw chain	If the chainsaw's blade has become gunked up, it can be immersed in a carburetor cleaning solution, and then scrubbed with a wire brush. Spray carburetor cleaner (in an aerosol can) can quickly remove any solvent remaining on the chainsaw's blade. Safety Note: It is recommended that you clean the chainsaw's blade before sharpening it. This is safer, and you are less likely to dull the blade by the cleaning activities. Also, it will be easier to see what you are doing during the sharpening activities. Finally, be sure to follow the safety guidelines for use and disposal of any cleaning chemicals.
2		Sharpen the Cutters	Fleam Angle The tops of some saw chain cutters have an line at an angle which is used to indicate the manufacturer's recommended Fleam / Vise Rotate Angle. This is shown as a red line in the picture to the right (click on the picture to see a bigger version).
	i	Inspect the chain to find the cutter most in need for regrinding.	When ground, the length on this cutter will set the amount ground from all the cutters. This ensures a consist chain which saws cleanly, neatly, and (hopefully) safely. Mark the top of this cutter with a red Sharpie (or use whichever colour you prefer).
	ii	Sharpen all the left hand (or right hand) cutters. Start sharpening with the cutter marked red in the prior step.	Chain Pitch File diameter Imperial Metric 1/4” 5/32” 4 mm 0.325” 3/16” 4.8 mm 3/8” 13/64” 5.2 mm 0.404” 7/32” 5.5 mm If sharpening the cutters by hand, a round file guide is recommended. If sharpening the cutters using a grinder, Ensure the grindstone's shape is appropriate. Use the wheel dresser to reshape it as necessary. Be sure to manage the heat during the process. Saw chains are typically not hardened steel and if the grinding is too agressive, the teeth will lose temper. Ensure the chain vise holds the saw chain securely, and also allows the chain to slide easily during the sharpening; adjust as necessary.
	iii	Sharpen all the opposite hand cutters. Start sharpening with the cutter to the left of the one marked red.	When grinding the cutters, it is important that the left and right cutters are equal length. It is a good practice to measure the cutters you just sharpened, and set the length of these cutters to be the same. Aim for a difference in lengths around ±0.01” (±0.25 mm). A micrometer is a good tool for measuring this.
3		Set the height for the Chip Gauges Chip Gauge	If the saw is generating fine (not chunky) sawdust, the chip gauge / raker will need to be filed down to increase the chip thickness. The chip gauge is the metal part of the saw chain which projects up in front of the cutter and sets the chip thickness. Depth Gauge Tool When filing down the chip gauge, be careful to not take off too much. If it is too short, the chainsaw will become too aggressive, and will also be dangerous to use. A depth gauge tool is really needed for setting the chip gauge's height correctly. If grinding the chip gauges using a grinder, Set the thickness for one of them first by hand. This one is used to set the depth for grinding the others. Ensure the grindstone's shape is appropriate. Use the wheel dresser to reshape it as necessary. As noted above, be sure to manage the heat during the process.
4		Oil the saw chain. In a dusty environment, this can attract dust to the chain, so it may be better to only add a light coat of oil.

File Size to Use

The file size needed, based on the chain used, should be as noted in the table below. It is best to consult your machine's manual though.

Husqvarna's file handle

This handle fits 4.0-4.5 mm round files and 6-8” flat files.

I prefer this handle style for sharpening chainsaw blades over the wooden file handles.

Tool Kit

Oregon Products makes a very useful field sharpening kit with the three most common chain files and a flat file for reducing the size of the chip thickness depth gauge. (Though they don't seem to show it on their web site; I bought mine via Amazon.)

The kit also includes guides/jigs for use with both sets of files, and the round file guide has marks for the fleam at 25°, 30°, & 35° to make the process easier.

A complete kit also includes a depth gauge tool and flat file for filing down the chip gauge's height.

Chainsaw Maintenance

Do not forget to also maintain the chainsaw.

Chain Catcher

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Remove burrs

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Lube sprocket bearing

1. After removing the chain:
1. Clean the area behind the clutch cover / sprocket cover.
2. Clean the guide bar.
3. Clean the guide bar's chain groove.
4. Check that the oil channel in the guide bar is not obstructed. Clean if necessary.


2. Inspect the guide bar, looking for any significant damage:
   1. Cracks in the guide bar,
   2. Dents in the guide bar,
   3. Excessive wear, especially in the chain's groove,
   4. The guide bar tip sprocket turns freely,
   5. The lubricating hole in the tip sprocket is not blocked, and
   6. The guide bar is straight.
   
   If the guide bar is badly damaged, replace it.


3. Inspect the chain catcher to ensure it is not damaged and that it is firmly attached to the body of the chain saw. Replace if necessary (see also, top picture to the right).


4. Dress the guide bar. A jointer & edger used for hand saws makes this easier and more consistent along the edge. (Do not use a handle on the file when doing this; the jointer/edger handle holds the file.)


5. Remove any burrs on the sides of the guide bar (see also, middle picture to the right).


6. Some chainsaws require you to lubricate the guide bar tip sprocket (if there is one) with bearing grease (see also, bottom picture to the right). Others want you to ensure the oil channel supplies oil to the sprocket.


7. When re-installing the guide bar, flip it over 180° from the way it was originally installed. This prolongs the life of the guide bar.


8. After re-installing the chain, ensure the chain does not bind. Also ensure it is not too loose, indicating that the groove is excessively worn. Either of these scenarios indicate that the bar should be replaced.


9. If you are putting the chainsaw away for the season (or even for an extended period), remove the fuel.

More Information

Books & Papers

• The Complete Guide to Sharpening (2003), by Leonard Lee


• The Fundamentals of General Tree Work (1996), G.F. Beranek.


• The Good Woodcutter's Guide: Chain Saws, Woodlots, and Portable Sawmills (1998), by Dave Johnson.


• The Razor Edge Book of Sharpening (2000 - PDF file), by John Juranitch


• The vendor's user manual which came with your chainsaw.

Videos & Presentations

• Oregon 520-120 and 410-120 Electric Chain Grinder Instructions (YouTube video)

Web Sites

• How Saw Chain Works, by Educated Climber