sharpening files

[JohnN]

Anyone ever done this ? From what I understand you can send them out or do them at home with acid. Have read that you can use sulfuric, nitric,or muratic. Does one work better than the other ? Muratic is rather easy to get.

 

[eggwelder]

did it once with sulfric. was a rusty old garage sale find. worked ok, still have it but you must remember to neutralize the acid thoroughly.

 

[JOHN ZUREKI]

I soak old files in muriatic acid. I have never used other acids because muriatic acid is easy to get. I'm not sure that the acid sharpens the file but that it cleans them and etches them. They do seem to cut better afterwards for a while at least. I don't know how files are really sharpend when they become worn unless they are re-cut. That is my take on it. JZ

 

[Zonie]

I've never tried it and I'm not about to now because I can't figure out why an acid would attack a big flat area like the front and back surfaces of the tooth and would leave the cutting edge razor sharp at the same time.

All of the times I've seen an acid used on a metal part, the sharp edges are the first things to be dissolved and rounded off.

 

[eggwelder]

Alexander Weygers discusses it in the book "the Complete Modern Blacksmith". the acid attacks the flats of the teeth, reducing the thickness of the teeth, leaving the edge sharp. it works, giving the file a little more use before it becomes a knife or something else.

 

[Tinker2]

For rusty old garage sale files I have used molasses





William Alexander

 

[Grizzly Adams]

I've never tried it and I'm not about to now because I can't figure out why an acid would attack a big flat area like the front and back surfaces of the tooth and would leave the cutting edge razor sharp at the same time.

All of the times I've seen an acid used on a metal part, the sharp edges are the first things to be dissolved and rounded off.

Perhaps the flat areas of the teeth offer a better/more nucleation sites for the acid to "bite" into than the much smaller surface area of the points of the teeth? Hard to believe that the thin edges though. I will have to try it and see.

I do believe I have seen a "chemically sharpened" fish hook though, and I will attest, they were sharp!

 

[JohnN]

I saw this on u tube and there was a mention of muratic acid as having a different effect (negative) on the metal as compared to sulfuric. The man in the video actually used a sulfuric acid based drain cleaner.

 

[matt denison]

I send worn files out to Boggs Tool Sharpening (do a search for the address)in California. They're good people, good service. It is cheap and they come back sharper than new. I'll send 8 or 10 at a time.

 

[jerrywh]

I have been doing it off and on for about 45 years with nitric acid. It works very well.They must be cleaned first with solvent or gasoline. I use 10%
to 7% nitric and etch for about an hour. Then rinse in very hot water an bead blast with very fine glass beads.
Don't waste any time sharpening Chinese files.
A flat dish is not a good container for this. A plastic pipe is much better, capped on one end.
They are almost never as good as new but almost.

 

[kaintuck]

I send worn files out to Boggs Tool Sharpening (do a search for the address)in California. They're good people, good service. It is cheap and they come back sharper than new. I'll send 8 or 10 at a time.

+2!
marc n tomtom