I'm in my early learnin on the filing. I used to just have them ground but you get three sharpenings because they grind so much. Some would be blue. Anyway, I bought a file guide deal that clamps to the bar. Grandberg? Something like that. Anyway I get them sharp with that and use it on the "good" stuff for now while I practice hand filing on my beater saws. This finger gash was from pushing the chain back against the guid stop after advancing the chain forward to the next cutter. I run the chain pretty tight so it has minimal deflection when filing. I'm probably pushing to hard. Anyway, that thight chain doesn't move easily and my had slipped. My stupidity. I'll keep fumbling along with this contraption as I hopefully transition to hand filing with some confidence.
