Chainsaw Repair

To add to my last post, my theory always was a file makes a perfectly flat chisel surface into the chains cutter bit.
Where as a round grinder disc...............
Only down fall of todays chisel bit files is finding ones with perfectly straight corners without being wavy. I know it was a problem back in the early 1980s.  I have not looked at the latest made files though.
I still have a unopened dozen of Windsor triangle files from the 1970s, as much as I square file they'll last me a lifetime