Chainsaw Chain Sharpening
Mrs. Bone decided I needed another project. Obviously, the ones I already had weren’t fulfilling enough to please her. So, she began creating a scenario to get rid of two trees in the yard that were obviously in the wrong place.
She said that right in the middle of the swamp we live in, there was a water shortage, and the other trees were suffering.
For Christmas that year, I got a new Husqvarna 450 Rancher with an 18-inch bar, an arborist rope, a slingshot to get the rope up in the tree, and wedges.
It’s hell having a wife who has industrial knowledge, along with farming, computers, and such. Don’t much get past her.
So, I utilized all the tools I was given, with her behind the wheel of my truck, waiting for me to give the signal to hit the gas and help get the tree falling in the required direction.
All went well, and I was allowed to take the rest of the day off. Of course, that was after I limbed both trees, cut them into firewood lengths, and piled the unwanted limbs in the delegated area.
Where was I?
Oh yeah, we are here to discuss chainsaw sharpening…
I put together an instructional for all of us who are not interested in reading the owner’s manual. And I am not about to give it to you in four languages. LOL
T-Bone demonstrates how to sharpen a chainsaw chain step by step, including proper file position, sharpening angle, cutter length, depth gauges, and chain tension.
Chainsaw Chain Sharpening Instructions
Shut the saw completely off.
Let it cool. Remove the battery on cordless saws, or disconnect the spark-plug lead on gas saws if you want maximum protection against accidental starting.
Clean the chain.
Brush away sawdust, oil, resin, and dirt so you can clearly see the cutters and depth gauges.
Inspect the chain before sharpening.
Look for cracked or damaged cutters, broken tie straps, loose rivets, or badly damaged drive links. A physically damaged chain should be replaced rather than simply sharpened.
Secure the bar.
Clamp the guide bar securely, but gently in a bench vise or stump vise. Leave the chain free enough to move around the bar.
Tension the chain correctly.
It should be snug enough that the drive links stay seated in the bar groove, but loose enough that you can advance the chain by hand.
Find the shortest cutter.
This is important. Ideally, all the cutters should end up approximately the same length. The shortest usable cutter becomes your reference.
Use the correct diameter round file.
The file size is determined by the chain pitch and cutter design. Do not guess based only on the saw’s bar length.
Identify the sharpening angle.
Most chains have a witness mark stamped into the top plate showing the correct filing direction. Many common chains use roughly a 30° top-plate angle, but use the specification for your particular chain.
Start with all cutters facing one direction.
Mark your starting cutter with a paint marker or Sharpie so you know when you have made a complete pass around the chain.
Position the round file correctly.
The file should sit in the cutter so that roughly 20% of the file diameter is above the top plate. A filing guide makes this considerably easier.
File from the inside of the cutter toward the outside.
Push the file forward through the cutter using smooth, even strokes. Only sharpen on the forward stroke. Lift or relax pressure on the return stroke.
Use the same number of strokes on comparable cutters.
Usually, only a few light strokes are necessary on a routinely maintained chain. A badly dulled or rocked chain (one that has struck dirt, rock, or another abrasive surface) may require considerably more.
Finish every cutter facing that direction.
Turn the saw or reposition yourself.
Then sharpen every cutter facing the opposite direction using the same technique.
Check the depth gauges, or rakers.
These determine how deeply each cutter bites into the wood. As the cutters are sharpened back, the depth gauges eventually need to be lowered.
Use a depth-gauge tool.
Place the appropriate gauge over the chain. If a depth gauge protrudes above the tool, file the exposed portion with a flat file.
Do NOT arbitrarily grind the rakers lower.
Depth gauges that are too low make the chain overly aggressive, increase vibration and kickback potential, and put much greater load on the saw.
Maintain the front shape of the depth gauge.
After lowering it, lightly restore the rounded leading edge rather than leaving a sharp, square corner.
Inspect the completed chain.
Make sure the cutters are reasonably even, there are no obvious burrs or damaged components, and the chain moves freely around the bar.
Reset the chain tension before cutting.
Follow the saw manufacturer’s procedure. The chain should be snug against the underside of the bar without being overtightened.
The Three Things That Matter MOST
Correct file diameter + correct filing angle + correct depth-gauge height.
And one mistake I would specifically warn you about:
Don’t keep filing a cutter just because you think “more sharpening” means sharper.
You’re removing some of the life of the chain every time you file it. Once the cutting edge is clean, crisp, and free of damage, STOP.
If you have any questions or comments about the instructions, please be pleasant and kind. Or watch the video, where I cover the instructions step by step.
You being kind might even get me out of the doghouse with the Missus. 🥴😁
