I have a bunch of machine files that I am too stingy to use!
Most of my filing machine work has been done with a 6" Nicholson half round bastard file with the tang ground off,and the other end ground to fit in my Butterfly's chuck. now that Nicholsons are Mexican,and soft as butter,I don't know where to buy new ones. I only hope they get their problems straightened out. I can't use their new files. The old files will easily file the new ones!
The die filer is a great machine whose use is very valuable,saving a lot of time,and enabling very accurate,dead square work.
As I have said before,they all run way too fast,which wears out the files,and leads to pinched fingers. I put a variable speed 1/2 HP motor on mine,and it is totally more pleasant to use. We had women working in my wife's jewelry shop who were afraid to use the die filer. Slowed down,they love to use it. My fingers used to get pinched pretty often,when the fast moving file would tip the work up,and slam it back down. My Butterfly doesn't have hold down fingers. Even if it did,we tend to do work too small to allow hold down fingers to work.
I have 3 die filers. One is a beautiful Duplex Die Filer. A very elaborate unit that must have been very expensive. It has tables above and below the file chuck. You can file down into holes in work that do not go clear through,preventing the use of ordinary filers. It is more fussy to set up than the Butterfly,so I use the Butterfly 99% of the time. Plus,I haven't gotten a variable speed motor for the Duplex yet. It's motor is INSIDE the casting of the body,and a lot more trouble to access. My chronic tiredness keeps me from doing some things.