Thanks both for the quick reply. After many hours manning chain saws to limb, buck, and fell, I can see the merits of a good saw file on the Hill concave blade. But, I'm most interested in mastering the old Hill method of sharpening the head. Ekin assures me that the batch of Hill Heads I have are super hard and he paints a picture that the Grizzlys I just worked are easy compared to the Hills. Not sure how much smoke he was blowing but I know darn well it is not impossible and I'd like to master the technique.
Tom, I'll give an 8" Grobet bastard a try for the initial work with plans to chalk and card the file to keep her going as clean as possible. Your video sparked a flame in me to get the Hill method down pat.
Thanks,
Daddy Bear