I am sorry to rehash this topic,
but after starting to resharpening my saws in the bush using file with hand guide, file with roller guide, clamp on metal oregon file guide and finally a 12volt handheld stihl stone sharpener, I still can't cut a straight cut after a few resharpens, it is very clear i'm a heavy handed right hander.
I see the oregon bench sharpener that sells for $400 about but is there a h/duty 12volt version of those, so I don't have to even think about the rubbish $35 versions.
cheers