hard chains

[Sam0207]

firstly thank you to this group for pointing me in the right direction in the past, i am always keen to learn as i go along.

 

I sharpen quite a lot of different peoples saws (or show them how to sharpen their own) and recently, on 2 occasions, i have come across chains that i cannot sharpen with a file, they are just too hard. I suspect they have been sharpened with a power tool previously and i am wondering if that has somehow re-hardened the cutter into something that my files, even a new file, cannot get in to?

 

i don't think that these are extra hard chains, they look standard enough to my eye however they are both makes i have never heard of before. the one in question at the moment has no manufacturers name but 3 joining rings stamped on it that slightly resemble the Olympic games logo. Any thoughts would be greatly appreciated to expand on my knowledge.

 

Sam

[Mick Dempsey]

Well, I’m guessing they’ve been run blunt and have ‘work hardened’

Ie. The metal has changed temper because of the heat.

 

Chuck them away.

Edited March 19, 2020 by Mick Dempsey

[Stubby]

2 minutes ago, Mick Dempsey said:

Well, I’m guessing they’ve been run blunt and have ‘work hardened’

Ie. The metal has change temper because of the heat.

 

Chuck them away.

This . You can get past the work hardened edge but it takes a lot of effort and you will loose fair proportion of the cutter . As Mick says , bin 'em .

[Rough Hewn]

If they are carbide tipped, you can't sharpen that with steel.

If you've got a proper bench grinder you can take the teeth back behind the hardened crap to soft metal.

Or as I find it's only one or two teeth on a huge chain I just grind them off.

[emoji106]

 

[maybelateron]

A while ago one of my 4ft chains for the 880 got overheated when it found some metal. It was a fairly new chain, so didn't want to chuck it away. As Rough Hewn suggests, I took it to out local Stihl agent who I have a good working relationship with. They touched it enough with the grinder to remove the hardened edge, but gently enough not to overheat it again. I then finished the sharpening with a file.

If the chain had been more than half way through its life I might have binned it.

 

[maybelateron]

We were splitting some Oak rings yesterday that we felled last October.

Look at what we found in the middle - very nice!

[Khriss]

ChainS are carbon steel, which gives a sharper edge ( and keeps it longer than stainless steel -ask any butcher which blade he prefers ) but it will harden when heated too much. K

[difflock]

7 minutes ago, Khriss said:

ChainS are carbon steel, which gives a sharper edge ( and keeps it longer than stainless steel -ask any butcher which blade he prefers ) but it will harden when heated too much. K

Soften surely, unless quenched after the heating, with natural slow cooling after heat, that would be tempering, or annealing.

Btw, I understand "work hardening" to be due to "hammering", or repeated mechanical stress cycles, not due to heat.

From memories of Copper work in school, peening, or planishing, then required annealing to soften the copper.

Edited March 19, 2020 by difflock

[Khriss]

Just now, difflock said:

Soften surely, unless quenched after the heating?

Doesn't seem to  ? air quenching is enuff. Tiny parts cool faster . Gentle with yr grinder is best, I use cutting grade discs as they softer / larger grit and remove more metal without cooking the tooth. The pink honing disc is harder / finer grit which IS best ( in the right hands ) k

[Stere]

Anyone try round dimond files, I've never used them but maybe the would be good for this re-harden buisness etc as they sell them for carbide chains

 

https://www.ezelap.co.uk/product-category/chainsaw-sharpeners/