Well, its not really a big deal. And it applies to sandpaper as well
as files. Simply make circles rather than a back and forth motion.
When you make straight line cuts you create lots of long valleys
which are harder to polish out. A circular motion by its nature
continually overlaps each previous cut at a different angle so you
have peaks like on meringue, easier to just shave off the tops in
the next step.
Where this is particularly handy is sizing or forming a plat
engagement ring, but the principles follow thru for most
applications. If you straight cut its pretty tough to blend the end
of the cuts up near the baguettes or whatever. I often see on such
previously sized rings a few tiny grooves near the top ends of the
shank, this is where somebody gave up. Using circular motion lets
you feather in the ends of the cuts, add in that the shank often
tapers(triangular cross section) which compounds straight filing
problems. Trying to polish out a vertical(for lack of a better
descriptive term) groove is much tougher than one that roughly
follows the line of the shank. This has to do with polishing angle.
I find the most effective angle to be something like 30-45 degrees
from the length of a groove. If your remaining grooves are all short
and semi circular you are more assured of having a good angle of
attack with the buff. If your grooves are straight you have only one
opportunity for an angle of attack and any embellishments/ornaments
on the shank can get in your way. BTW try a soft white 3/4" brush on
the flexshaft for this, you get excellent control of just where and
how you polish in tight circumstances. Typically I brush details
before going to the Baldor for the main finish. Forget Chinese
brushes, get the German. The difference in cost is moot once you
consider the difference in performance.
I don’t know if I’ve described that clearly so just take some stock
and try it out. This also works for gold but its typically not as
crucial as gold polishes out pretty easy, except for flat discs.
Here you need a dead flat mirror finish and circular sanding will do
it for you.
Hmmm, for not being a big deal I got a little wordy, sorry.