Bill Schwab wrote:
David Billington wrote:
Jim Wilkins wrote:
On Apr 6, 2:32 pm, Gunner Asch wrote:

...
One of the old exercises for apprentic machinist was to make a perfect
cube, using nothing more than a file, for a grade. Took a considerable
amount fo time to do, yet all apprentices had to do it.
....
Gunner


Interesting. I've seen machinists' faces go from smug to panic when
the part I wanted them to make required some careful hand work, like
filing to a curved line. It didn't help that I had made a sample.

Jim Wilkins

After using a file for many years I was shown by one of my
engineering workshop instructors, when he saw me filing a radius, how
to file a radius correctly and it made the world of difference to the
outcome. I thanked him but have often wondered why such basic
information was not taught as standard, maybe it was thought we
didn't need to know that sort of thing because of the courses we were
on and it way too basic. It's not something I have ever run across in
a book either but have not looked specifically for it.

I have not seen it either - can you explain it for us?
In case you didn't see my response to Jim Wilkins, I posted the following.

I've done the same but I was thinking of filing the final smooth curve.
On say a 90 degree corner and holding the piece with each face at about
45 to horizontal what I did originally, as I had never been shown, I
just moved the file forward and rocked it from the near face to the far
face so the contact point travels away form you to create the curve. The
instructor showed my to start with the file parallel with the far face
and moving the file forward, rock it back, to end the stroke with the
file parallel to the near face, in this way the contact point travels
back towards you during the operation. This instantly gave me a much
better finish and radius and it's the way I've done it ever since.

Bill