Diagnosing tooth shape

[STOVE]

I was looking over a chain last night and I noticed some of my teeth have a bulge in the leading edge. See the sketch below. I will also take photos of the chain.

What causes this in a sharpening stroke? Trying to understand what I am doing to lose the straightness of the tooth edge

 

[SawAddictedFarmer]

I was looking over a chain last night and I noticed some of my teeth have a bulge in the leading edge. See the sketch below. I will also take photos of the chain.

What causes this in a sharpening stroke? Trying to understand what I am doing to lose the straightness of the tooth edgeView attachment 481740

Assuming your using a file that's just from not keeping it at the same angle every stroke.

 

[Woodtroll]

Or it could be that you're rotating your body during the file stroke, instead of pushing straight through with just your arms. Sometimes it's tough to isolate the arm motion to just a push that is both straight (on a 30-degree or whatever angle you choose) and also flat relative to the top flat plane of the tooth. If you have a shop vise that helps a lot, especially if you can get in a position to rest your upper body against the vise or bench to keep it in a consistent position, and pull each tooth into the same position on the bar before you start filing.

I think a filing guide helps establish a straight motion, as you can easily tell visually when your file angle starts to get off. I like this one because it's simple and a clear visual reference yet it doesn't require any clamping of the file or extra hardware, but I'm sure there are others:

Amazon.com: Tecomec New! Magnetic File Angle Plate 25° & 30° for Chainsaw Sharpening USE : Patio, Lawn & Garden

Amazon.com: Tecomec New! Magnetic File Angle Plate 25° & 30° for Chainsaw Sharpening USE : Patio, Lawn & Garden

www.amazon.com

 

[Wilhelm]

You are not pushing Your file in a straight stroke.

I really like the Archer FastFiler roller guides, they also help keep near identical cutter length featuring side and depth rollers.

Con is You are comited to the guides angle, unless You make custom side rollers.
I did the latter.

 

[Seachaser]

There’s several YouTubers that explain what happens. They even do it and then how to straighten the edge back out.

 

[Lawless]

Could also be dipping and raising the file handle in the stroke, which is harder to watch for than top plate angle.

 

[Stihl036]

It's a saw chain, not a fiddle!

 

[STOVE]

It's a saw chain, not a fiddle!

A great picture you painted

 

[STOVE]

I appreciate all the responses, I will be going some more filing shortly. I am also wondering if the handle shape promotes a certain stroke.

 

[Philbert]

One of the reasons I strongly recommend holding the bar / chain securely in a vise of some kind, and using both hands to guide the file.

Think of a pool cue: once you decide on the angle you want it to travel, you don’t want it to change part way through the stroke.

Philbert

 

[MtnHaul]

One of the reasons I strongly recommend holding the bar / chain securely in a vise of some kind, and using both hands to guide the file.

Think of a pool cue: once you decide on the angle you want it to travel, you don’t want it to change part way through the stroke.

Philbert

I agree that using both hands really helps to guide the file while the bar is held in a vise. I do have to watch that I don't end up pulling the file instead of pushing it since pulling seems to make the file turn into the tooth at the end of the stroke, at least with my skill level and technique.

 

[Brad Button]

Use one of these and you will not have the problem of different angles; just take the same number of swipes on each cutter. https://www.oregonproducts.com/en/o...etter-consistency-and-accuracy,-23820/p/23820

 

[bucketofguts]

I have been sharpening by hand with a round file for over 40 years. It is not a PGA golf swing. You need a good sharp file with a handle you like. You need to be comfortable "reminds me of a blond joke" wonder who will get that one? Good light. Follow the line angle on the tooth. Level push strokes. When the burr forms and falls off you have a scary sharp tooth that will last and throw chips for your rodent cage. I go much slower than BBR. For the person that can lie down on the saw and sharpen a proper tooth on a four foot .404 chain you have my respect and admiration.

 

[edisto]

I appreciate all the responses, I will be going some more filing shortly. I am also wondering if the handle shape promotes a certain stroke.

I don't use a handle. Using one makes the file longer, which makes it harder to control with one hand. If I sharpen on the saw, my left hand is holding the chain in place. The tang sits in my palm, which allows me to put my index finger on the back of the file.

 

[Philbert]

Some people find these helpful.

Magnetic. Have been around a long time. 25°, 30°, and 35° combinations available.

(Labels / markings are mine)



Philbert

 

[ZERO]

Take into account bar rail slop/slosh from normal wear. Filing the chain in the middle causes the preverbial bow effect. I tend to file mine close to or on the sprocket.

 

[legdelimber]

I'm a little fond of snugging the chain tension and then clamping the bar (still mounted obviously) in the bench vise, near the nose. Helps a little with keeping the chatter under control too.
As for file handle types? If it seems to affect how your hand grips (tendons and arthritis and such..) Experiment a little with wrapping some tape or other handle ideas. Whatever gets it so that we can do it right?
IF the added length of the handles are interfering, Might try small hex nuts slipped onto the tang or some of that fuel stiffened Tygon line that's in the trash can.
Got a blob of epoxy left after a job? Grab a file and roll the tang in it!

I lucked out and had a few good mentors who left a few good ideas that I can sort of remember.