Keep extra files on hand so you won’t have to drive 20 miles for more in the middle of a job. Change your file when it starts to slide across the teeth. A dull file slips and you don’t want your hand slipping across the teeth of a chainsaw.
Change your file sooner than later. A dull file is more work and more dangerous.
Some experienced hand filers, myself included, use the next smaller file halfway through the tooth to keep a nice hook.
Keep the gullet of the tooth clean when filing.
There are 4 common sizes of chainsaw files 7/32, 13/64, 3/16 and 5/32.
The box your chain came in will tell you what size file you need.
7/32″ Chainsaw Files
13/64″ Chainsaw Files
3/16″ Chainsaw Files
5/32″ Chainsaw Files
Depth Gauge Files