Sharpening Files

[JHowell]

I don't know how many here use files and rasps, but I do, a lot. After a while they get dull, and some of them are damned expensive. I read on a machinists' forum about chemical sharpening and decided to give it a try. I used muriatic acid (hydrochloric acid) from Home Depot and a tall, narrow glass jar. I did this outside, with a nice breeze blowing, wearing long chemical-resistant gloves and lab goggles. The longest files would sit on the bottom, while the shorter ones I suspended from the neck with clamps. It took, generally, about 15 minutes for a rasp or large file, a little less time for a fine cut. I don't throw anything made of tool steel away, so I had a pretty good batch of worn out files. By the end of the batch the acid was pretty brown and funky, and it took noticeably longer for the "dull" look to go away. When the acid seemed spent I diluted it with water, then neutralized it with baking soda.

The files I sharpened may not be quite like new but they're vastly better than they were. I've also heard that re-sharpened files don't hold an edge as long as the original, we'll see.

For what it's worth,

Jack

[KurtHuhn]

I forge my worn out files down into knives.

[Kettletrigger]

I've read more than once that files can be sharpened by leaving them outside overnight to build up a coat of rust. Never tried it myself.

[Frank]

I have Ferric Chloride for etching pattern welded (damascus) steel. Do you think it would produce the same result on files as the Muriatic Acid?

[KurtHuhn]

Based on my experience - yes. One is an acid, the other a salt, but both have a similar effect on steel. It can't hurt to try, at any rate.

[bluesmk]

Yes , I use a lot of files this is intereting, and like you Jack I throw almost noting away!
Dan
Gabrieli Pipes

[Nick]

Veryy cool! Thanks Jack!