mystery cutter

[farmer steve]

i have a stihl chain that has one cutter that will not sharpen. the file slides across it like a hot knife through butter. the rest of the chain is fine. tried switching to a new file and no better. i am wondering if it is possible that this is a carbide cutter that got mixed in when the chain was made? anyone ever see this?

 

[Gunn]

Take a picture. Carbide doesn't look like a standard cutter. If it looks the same as the rest it's probably been heated up to the point of hardening.

 

[DSS]

I've seen this a couple times. I had a loop of LGX with two or three cutters on one side I couldn't sharpen. I ground them back a little till I got past the hard part and could file them.