Whether it’s a file or a chain grinder, they both take practice, sharpen with what you have
and take a new chain out on the saw, try your own half an hour before you want to quit
and see how it goes, that way you can take it home if it doesn’t work so good, have another
go at sharpening and try it again next time out.
Some chains are harder to file than others, their metal is harder, the original factory profile
can be very difficult to reproduce as it’s not the shape of a file, some chains are easier than others
because they are not too far off shape to get close to with a file.
It takes time to build up a picture of all the cutter shapes angles and hard or soft material used.
Good files are a must, Stihl or Pferd are good, Oregon too, there are diamond files but expensive,
you need a depth gauge too to set the rakers, a chain well sharpened will still not cut if the rakers
are too high.
Make sure you use the right file size too.