Im a grinder. I use a razor sharp II square grinder and like the result. I just swap chains in the woods. Dirty wood I use round and hand file but it has to be a lot of dirty wood before I swap to round.
I can't help you with the part # I only have 3/8 but I bet someone here knows.
Carlton File-O-Plate part #'s for .325" chain are;
.325" Semi Chisel - 65980
.325" Full Chisel - 65981
Worth their weight in gold these little things
Matt (and others) I don't use a filoplate but I had a PM from someone buying up a set of milling gear and he said that the seller said that filoplates don't work on ripping skip chain, That sounds wrong to me - what do you think?
Free hand only. The only trick I use is flipping the saw over upside down to do the harder side first. When that side is right , I flip the saw right side up for the easy side to me. If you are lefty reverse the process.
I simply count strokes, even on knives, which is free hand and by eye.
Good trick about using the other side - I must do that on my mill!
Counting strokes is fine for knives, but knives are different to CS chain. Even if the chain cutters are all perfectly shaped and sharpened to begin with they do not all wear at the same rate. The key to sharp chain is removing cutter edge glint. If I touch up often enough I find around 2 strokes is sufficient but I watch for any residual glint and add extra strokes till the glint is gone and then 1 more for luck.
Hand file, and I can tell if the chain is good and sharp when the chips hurt.
Owie. Good night and don't forget those clocks.