sharpening files

[jerrywh]

I know this topic has been talked about before but I thought maybe someone might be interested in how I sharpen files. I have been doing this for at least 40 years.
  I use a piece of plastic pipe about 2" inside diameter and 12" tall with a cap glued on one end for the acid container.  I fill it to about 2" from the top with 7% to 10% nitric acid.
  First I clean the files of any material that might resist the acid with solvent and then hot soapy water. Then I immerse the files in the acid for about 1 to 1 1/2 hours. If the acid is warm it works a lot faster. Even if you don't notice any reaction the acid is still eating the steel so don't be fooled by the apparent inactivity.  After this I take the files out a rinse them in hot water.  Then I bead blast them with the finest glass beads just until they look like clean steel or a new file.
 Always use rubber gloves when working with acid and use eye protection. It will burn holes in your clothes if you get it on them but at 10% it is not very reactive on your flesh at least not very fast. If you get it on your hands you have time to wash it off before it does any great damage.  Do not get it in your eyes.
   When sharpened a good American made file works better than new in my opinion. Don't waste your time doing Chinese files.  This can save you a lot of money at the price of today’s files.

http://www.sciencecompany.com/Nitric-Acid-Concentrated-500mL-P6387.aspx

  I learned this years ago, The process was in an old blacksmith book published about 1890.

[ddoyle]

Priceless. Before I knew better I abused a large and admirable collection of files. Restoring them would make me feel a lot better about my transgressions. (plus I'll have more files to use)

Here comes the "pay later" portion of my file wielding apprenticeship.

[mossyhorn]

Will this still work without bead blasting as I don't have a bead blaster only a sand blaster

[jerrywh]

 It still works without bead blasting but they should be washed in Baking soda and washed in boiling water then sprayed with WD40. They will have a rusty look if not bead blasted. The WD40 will dry. WD stands for water displacing for any who don't know.

[Dennis Glazener]

Jerry,
I don't have any Nitric Acid but I have several gallons of muriatic acid. Have you ever used that? Seems to me I read something awhile back about using muriatic acid to sharpen files.

I assume the difference in your technique would be the time left in the acid.
Dennis

[Jim Kibler]

I've had quite a number of files commercially sharpened and I have mixed feelings.  They generally seem sharp, but the way they cut sometimes seems different than a new file in my opinion.   Some tend to chatter a lot more.  I'll probably still send some out though.  I believe the commercial process uses a water / abrasive blast from the back side of the tooth to sharpen.

Jim

[ddoyle]

Now if only I could find a way to convince all these chipped teeth to grow back

[kaintuck]

boggstool.com
sharp/cheap/easy..............

marc n tomtom

[jerrywh]

 I never tried muriatic but if it will eat steel it will probably work.  I check mine under the microscope after I do them. You can see tha tthe yare sharp. Some cheap files are just case hardened mild steel. The acid will eat off the case and then they are useless.

[Bill-52]

I was given a number of old, worn out files.  I followed the same process as Jerry with one exception -- I used white vinegar and let them sit in the tube for several days.  They came out almost like new and my shop had a nice aroma.

[bob in the woods]

I have used 10 % pickling vinegar with success.