Also, a place called "Boggs Tool" makes a business of "liquid
sharpening" of files. They used to charge 15 cents an inch plus
shipping. I used to save up a dozen file or so and send them in. I am
told that you can only do that once, so a friend of mine files a nick in
the tang to remind him to toss it or recycle it next time it goes dull.
I liked the result, but another guy I know wasn't all that positive
about it.

Pete Stanaitis
------------------


Jan Howell wrote:
In article , Koz says...

Skimming though a 1904 metalworking text section on shop hints, I came
across this:

Sharpening files. To sharpen dull and worn out files, lay them in
dilute sulphuric acid, one part acit to two parts of water over night,
then rinse well in clear water, put the acid in an earthenware vessel.
(typed exactly as written, by the way)



Years ago, I'm buying files from Boeing Surplus and some files are dyed purple.
I ask the checkout guy why. He allows that that indicates that they have been
sharpend. When I ask how, he says: "dipped in acid."

Years pass and I buy some really rusty flea market files to make scrapers. They
were so rusty that the type of cut couldn't be seen. Having read about the salt
and vineager process, I try it first. The files come out so sharp that I don't
want to make scrapers of them. A second set of junk files yields the same
results. I feal a little guilty grinding on relatively good files.

Jan Howell