Chainsaw Sharpening

In our quest to become the world’s best chainsaw blog, we often ask ourselves some basic questions, such as: What is the most important piece of the chainsaw performance puzzle?  The single, most relevant variable governing the cutting performance of your beloved chainsaw is the chain.  Think about it, it’s called a chainsaw for a reason.  The chain does the actual sawing.  We’ve all seen the videos of some well meaning guy sawing away at a huge log that is much too big for the saw being used: the dude’s pushing and rocking the saw back and forth. The saw’s engine is bogging and groaning, and, after a couple of minutes of agonizing footage that you were afraid (or hoping) might document some horrible accident, this chainsaw warrior proudly vanquishes the mighty log.  Besides using a saw that is too small for the task at hand, and yes, besides the poor technique, there was another factor at play.  A factor that costs next to nothing, and improves performance and safety dramatically.  A properly maintained cutting bar with a sharp chain.

There are many different products available to keep your trusted saw razor sharp and ready for action.  These sharpening systems range from a few dollars for the appropriate sized file to several hundred dollars for a specialized grinding machine.  If you are new to saws or only use them occasionally, it doesn’t make sense to fork out the big bucks for a professional grinder, and you probably aren’t comfortable (or don’t have the time) to start in on the simple hand filing approach.  That’s where the bar mounted file guide comes in.  Priced at around forty dollars, these guides offer an almost fail-safe, easy to use option to keep your chain razor sharp; thereby ensuring optimum performance and safety.

World's best chainsaw blog pic of MS 271 with a Granberg G106-B

The Granberg G106-B File-N-Joint attached to a Stihl MS 271

Another great pic from the world's best chainsaw blog.

Up close and personal with a Granberg G106-B File-N-Joint.

There are many different bar mounted file guides out there.  Stihl, Oregon, Granberg, and various Asian brands all offer a version.  The one feature that is essential when choosing a bar-mount file guide is all metal construction. The consumer grade guides have plastic construction in key areas that lead to a too inconstant filing angle due to the plastic’s flexibility, as well as being parts that would not stand up to long term use.  Oregon and Stihl offer all metal bar-mount guides, but they are expensive.  The best buy in these guides is the original from Granberg.  The G106-B File-N-Joint can sharpen your chain to the precise angles as specified by the chain manufacturer.  it can also be used to precisely file the rakers or depth-gauge in 0.010 inch increments.  Although the file guide can be used to file depth gauges, it is much faster and easier to purchase a separate gauge that, in conjunction with a flat file, quickly and easily files depth-gauge teeth to the appropriate height.

World's best chainsaw blog pic of a depth gauge tool.

A Stihl depth gauge tool.

The Granberg File-N-Joint mounts easily and securely to the chainsaw bar and allows you to consistently file the same angle to your chain’s teeth.  Once the guide is mounted to the bar and the appropriate angles have been set, the Granberg allows you to sharpen each right or left cutter tooth in succession.  After you have finished sharpening all of the teeth on one side, you can quickly flip the file to the other side and file each tooth to a razor’s edge on that side.  It is a good idea to count the number of file strokes used for each tooth in order to keep the cutter teeth length the same in order to ensure a smooth, straight cut.  You should also pay attention to how hard you press the file on each stroke in order to be consistent with the amount of material you remove from the cutter with each stroke.  Consistency is the key.  If you sharpen your chain after every two tankfuls of fuel or so, you will find that two or three strokes of the file are usually sufficient to restore the cutter’s edge.

World's best chainsaw blog image with too much information.

A close-up pic of a Granberg G106-B with words and arrows.

After sharpening your chain, be sure to clean it thoroughly to remove as many of the metal file tailings as possible.  As always, safety first, the small filings can really travel great distances as you are filing, so remember to wear properly fitted safety glasses.

Chain Basics

When sharpening your chain, the essential chain information you must know includes:

  • The Saw Chain Pitch- this is the size of the saw chain. Pitch is defined as the distance between the center lines of any three consecutive rivets divided by two.  The larger the pitch, the larger the chain.  Saw chain pitch also tells you what size round file you need to sharpen the chain (see table).  The pitch of the chain is designated by numbers stamped on the chain’s drive link for Oregon chain, and by the number stamped on the cutter for Stihl chain.
  • Another Info-rich close-up from the world's best chainsaw blog.

    A close-up of Oregon 72 RD Ripping Chain compared to Stihl 23RS Rapid Super Chain.

  • Another crucial piece of information needed to sharpen your chain are the angles used to file the chain properly. These angles are different for different chains.  There are two angles to consider: The top plate, or cutting, angle (typically 25° to 35°), and the tilt angle (typically 0° or 10°).  Stihl chains require a cutter angle of 30° and a tilt angle of 0°.  Oregon chains will vary (In North America, if your saw is not a Stihl, it probably came equipped with an Oregon chain.)
  • World's best chainsaw blog detail of a cutter

    What the heck is a “depth gauge”, anyways?

  • The final piece of essential information concerns the depth gauge setting for your chain. The depth gauge, or “raker”, is the distance from the top of the gauge, or “raker”, tooth to the top of the cutter tooth. The depth gauge essentially limits how big a “bite” each cutter can take as it travels over the wood.  As in life, biting off more than you can chew is a bad thing.  A bigger “bite” from each cutter greatly increases the force required from the engine which can damage the saw or chain.  Too big a bite also greatly increases the reactive forces of the chain.  The saw will push or pull much harder on the operator and greatly increase the chance of a sudden loss of control.  This is especially important in the “kickback” zone.  If the depth gauge is too low, the kickback forces will be greatly increased.  If the depth gauge is not lowered as the chain wears, cutting performance is quickly reduced.  The use of a depth gauge tool makes adjusting this essential part of chain design almost fool proof.

 

Cockapoos and depth gauge tools.

A close-up of a Stihl Depth gauge tool with my handsome dog in the background. He is much less blurry in person.

Round File Size According to Pitch

 

Oregon Chain Type/ Pitch File Size Stihl Chain Pitch File Size
25, 91   (1/4″ and 3/8″ low profile) 4.0 mm |  5/32″ 3/8″ PICCO 4.0 mm |  5/32″
90     (3/8″ narrow kerf) 4.5 mm |  11/64″ .325″ 4.8 mm |  3/16″
20,21,22,95  (.325″) 4.8 mm |  3/16″ 3/8″ 5.0 mm |  13/64″
16,18,26,27,72,7375    (3/8″ and .404″) 5.5 mm |  7/32″

 

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