I Hate Fractions: Help with a File

There is no saw chain that takes a 3/8 file.

Determine the pitch of your chain.

91 Series chain-Lo-pro, requires 5/32" file
.325 Pitch requires 3/16" file
3/8 chain-requires 7/32 file or 13/64 if your running Stihl (although I sharpen mine with 7/32)

If your still confused, just post what is imprinted on the tail of the bar and someone here will tell you exactly what you need.

Fraction - Decimal

My FIL has filed with 7/32" files on 3/8 pitch chains forever. I've used most of his saws and can honestly say that he does a fantastic job sharpening. I even had him give me a lesson last summer. I think he was happy to see me taking an interest because most people that use his saws simply drop them back off once they get dull and let him sharpen them again.

Your good to go with the 3/16" file. That is the proper size for .325 chain. Just sharpen to 25-30 degree with a slight uptilt on the file when you are stroking through the tooth.

aandabooks said:

...with a slight uptilt on the file when you are stroking through the tooth.

Click to expand...

Why the upward tilt? The chain tends to lean over a bit from slack in the groove so a file held level already applies a upward tilt relative to the chain, so I tend to put a slight downward tilt to compensate.

Also, don't confuse or equate 'pitch' and 'file size' required to sharpen the chain.

LLigetfa said:

aandabooks said:

...with a slight uptilt on the file when you are stroking through the tooth.

Click to expand...

Why the upward tilt? The chain tends to lean over a bit from slack in the groove so a file held level already applies a upward tilt relative to the chain, so I tend to put a slight downward tilt to compensate.

Click to expand...

Oregon chain recommends a 10 degree upward angle. Stihl recommends that the file be flat or 0 degrees. I find that I seem to get my best cutting with the slight upward tilt. Your cutting may be different than mine. It doesn't take more than a few swipes to try it out and if it doesn't work, at least you gave it a shot and can go back to your normal routine.

The top plate angle should be 25 to 35 degrees. It depends on what kind of wood I'm cutting as to what how angled I will sharpen my chain. Generally if you follow the witness mark, you'll be ok.

Since I've learned to hand sharpen a chain, I find myself experimenting more and more. If you really want to see a chisel chain cut fast, file the top plate to 40-45 degrees. You won't make many cuts before it dulls but they will be fast cuts.

WineGuy, You might already know this but this point jumped out at me in your original post: you say your chain has a .325 pitch and uses a 3/8" file. I agree with anaabooks that no saw used by most sawyers on this and other sites needs a 3/8" round file to sharpen the cutters. I also have the impression that you are relating chain pitch to file size. They are not related (Corey is right on). Chain pitch is the distance between three rivets on the chain divided by two. So, if the measured distance between three rivets is .650" and you divide this by 2, the chain pitch is .325. This measurement is not related to the file size needed to sharpen the chain.

I believe this info is correct and if I was incorrect in my assumption about your relating chain pitch to file size, I apologize for the error.

Edit: My Stihl chain has a .325 pitch and requires a 3/16' file to sharpen the cutters. There is a guide line or lubber line or witness line/mark (thank you andabooks) on the top of the cutter indicating the correct angle (30deg) to sharpen the chain. Keep your file parallel to the that line and you will be at 30 degrees. I have also been told that this guide line is the farthest you should sharpen your chain because additional sparpening weakens the tooth so it might break off and fly in a random direction (your eye). Also, sharpen from the "inside face" of the cutter to the "outside face". And, with due respect to those who have much more experience than I, I would recommend that until you get a lot more experience with chain sharpening and the effect of each small change on the chain's cutting characteristics, you follow the sharpening instructions of the chain manufacturer. Stihl and other companies have bright engineers designing chain to cut well, last long and be reasonably safe.

Best Wishes to all, John_M