Hand Filing Chains - Switch to smaller diameter file as the chain tooth is getting narrower?

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Minister of Fire
Hearth Supporter
Jul 11, 2008
Northern NH
I have hand filed for years with a filing jig. I was going through my pile of nearly worn chains and came to the conclusion that as the chain is filed that the initial "hook" that comes with the chain tends to flatten out and forms a flatter angle as the filings proceed. This seems to lead to a law of diminishing returns for each successive filing. It cuts okay initially but rapidly loses its cutting ability. It is especially noticeable when transitioning to a new chain, as long as I keep the chain out of the dirt, I can go a couple of tanks but as the chain wears down, I end up quitting sawing long before the tank runs out. Looking at the teeth, they are sloped so the height of the tooth is getting lower but with the same diameter file its cutting less of a tangent making the hook angle shallower. Note I do adjust the height of my rakers so its not a case of just not enough cutting depth.

I come to the conclusion that at some point I need to drop the file diameter to get the hook angle back to where it was. Is this a correct assumption? If so any pointers on when?.

I get pretty good life off my chains but could get a few more filings if I could get the hook back. I usually do most of my cutting with snow on the ground to keep the saw out of the dirt and rocks but this winter so far has been a dud. Where I normally would have a couple feet of snowpack and using snowshoes I got 3", although the weather pattern looks like its going to shift and start snowing without changing to rain.

Thanks for the help
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As the teeth are filed back they get shorter vertically as well. The file needs to be lower to compensate. There should be 1/5 of the file above the tooth. You may need to adjust the jig to drop the file height. If the file is cutting into the tie strap or about to, then you should use a smaller diameter file.
Yup, and sometimes you even need to use a different file only on the teeth that are coming back from damage, like right now on my 2152 as I approach the guide marks on about 3 teeth that were damaged badly a while back. I've lost the hook and I need to use the 3/8 lopro file on those three or four .325 teeth when most of the chain is only 1/2 - 2/3 used up. I should be able to bring almost all of the teeth back to the guide marks fairly evenly anyway. This situation happens rarely to me when I'm not paying attention. Duh

using a file guide simply cramps your style
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If you are filing correctly, there is no need to change file size with tooth wear. You need to keep the file a constant depth into the tooth height as it wears away. This is relatively simple to do if you free hand file. I recommend that people learn to sharpen in this manner. It's five minutes every tank or two. It's important that you are using a slight, approx 5-10 negative angle across the chain and if course follow the witness mark on the chain in regards to the other angle.

You should not be changing file diameter.
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I am wishy/washy here as my saw experience is limited.

I am running a Husky 345e (c 2007). On my chains, I can use the same file from new back to the wear mark on each tooth, and have so far only had to scrap chains because I have filed each tooth back to the wear mark. I have never yet had to scrap a chain because chain stretch exceeded the tension adjustment, and I have never considered changing my file diameter for sharpening.

I have zero experience with other Husky saws and chains. Keeping up with filing your rakers is good thing.

I am tagging @Ashful at this juncture as he is familiar with a lot of the Stihl line. I have no experience with Stihl saws, but they are a highly regarded line, and both Stihl and Husky are serviced (local to me) by the same shop I happy to deal with 15 years after new purchase.

I have seen zero documentation from Husky that at a certain point a different diameter sharpening file is suggested.

My only contribution to the Husky/Stihl debate is to choose which repair shop you want to deal with 20 years in the future, as both saws can last that long with minimal maintenance.
Could the temper on the tooth also be different at the back of the tooth? A different amount of temper could allow it to dull faster.