I found this during my search on using my chain sharpener, maybe it will help this thread.
Pro Saw Chain
Gullets Explained
How do gullets form?
Gullets form when chisel cutters are square ground or square filed.
Why do gullets have to be removed?
When gullets are allowed to get long, they make it difficult for the sharp cutter to get at the wood. This makes it difficult for the chain to feed. Here is the reason: Every time a cutter tooth is sharpened, it gets shorter. As the tooth becomes shorter, the "set" or the amount the cutter sticks out beyond its chasis is reduced, too. Gullets retain their set and if allowed to get too long, they rub in the cut. also, long gullets impede chip flow.
What is the best way to remove them?
Remove them with a round file or a grinder.
Why can't I grind out the gullets at the same time I am sharpening the tooth?
The stone (or file) angle necessary to sharpen square chisel chain makes it impossible to remove the gullet at the same time you sharpen it. If you attempt to do it, you will end up cutting into the chassis above the back rivet hole on the tie strap. Damage to the chassis in this area will weaken the chain and cause it to break. Some grinders are setup to remove more gullets than others, but no grinder is able to remove the gullet in the same process as sharpening.
How does the factory sharpen a chain without leaving a gullet?
This is a good question and it has a simple answer: They sharpen the cutter teeth before they assemble the chain. The factory doesn't have to worry about the tie strap under the cutter because it is not there.
Do the gullets need to be removed after each sharpening?
No. Most professional saw operators remove them every three to five sharpenings. It all depends on how much of the cutter tooth is ground off on each sharpening. Whenever the gullet grows beyond an 1/8" it needs to be removed.
