Sharpening files?

Gunner Asch fired this volley in news: snipped-for-privacy@4ax.com:

Gunner, I've tried it, with several variant "resist" methods. Muratic acid likes iron.

The results go from "not at all" to "Gosh! That worked!" to "DAMN! It took ALL the teeth off!".

The only resist method that I've found that ever worked for me was to firmly draw the file backwards over a hard, rounded-profile with a single thickness of bed-sheet cotton damp (but not WET) with oil.

This is NOT a trick that works very well for that emergency shipment of files to a new machinist. You might frustrate hell out of her.

The one thing I have found about this method, and why I stopped doing it, is that the new edge you get has no backup metal, and dulls very (very!) fast.

LLoyd

I skipped the meeting, but the Memos showed that Gunner Asch wrote on Sun, 08 Feb 2009 17:12:36 -0800 in rec.crafts.metalworking :

Complete speculation on my part, but could that be something done on a shaper? The "old fashioned" back and forth plow? Not being a mechanical genius type, It has taken me a lot of "I wonder how that's done?" time to figure out it might require a shaper. But I have no idea.

-- pyotr filipivich We will drink no whiskey before its nine. It's eight fifty eight. Close enough!

The traditional method, and the origin of the standard file configurations, is to cut into a flat piece of annealed steel on an angle with a chisel and hammer. They were made that way into the mid-19th century. But a machine to do the job had been invented in the early 1800s and took over the market sometime around the Civil War.

It had a reciprocating hammer and a sliding bed on which the file blank travelled. The spacing of teeth was controlled by the travel rate of the bed. The file blank laid flat on a sheet of lead on the table, to protect the file teeth on the back side.

I don't know how it's done today but it's probably some advanced version of the original machine.

-- Ed Huntress

Battery acid. Don't leave them in over night. DAMHIK ;-) Beyond that, I think it's trial and error. Start with 1 hour and see how it works.

RWL

I've had reasonable luck using hydrochloric acid (sold as swimming pool acid). If the files are not completely thrashed, many can be made almost as sharp as new, although they do not stay sharp nearly as long as a new file. If you are lucky, they will stay sharp 60% as long or a little more, most seem to last 40% to 50% as long.

I found that the files must be clean, with no oil, grease or packed in dirt. Clean them up as much as you can with a file card or a wire brush, then wash in solvent or detergent to get any oil or grease off.

Put only one file in each container of acid, I used PVC pipe of an appropriate size and length with a cap glued on one end for each file. Fill the tube near the top with straight pool acid, do not dilute. I know you have enough sense to take the right precautions using acid. I set a group of the tubes full of acid in a 5 gallon plastic bucket to keep them upright and catch the worst of the spills and drips.

If at all possible do this operation outside and away from any iron or steel that you do not want to rust, as the acid fumes will rust any iron or steel that is at all close.

Put the files in the tubes with the acid, and start checking them in about

1/2 hour. There seem to be big differences in the time it takes to work for different files. The metal will start to look sort of matte gray as they near completion. Most seemed to take from one to four hours, but check the first ones fairly frequently until you are comfortable with the process.

When you think a file is done, remove it from the acid, wash it in lots of running water and then dip it in a baking soda solution to neutralize the last of the acid and rinse in clear water again. Dry the file with compressed air, then give it a LIGHT coat of WD40 or whatever your choice of a LIGHT rust inhibiting coating may be.

You can re-use the acid in each tube several times before it becomes too slow to work well. At this point the tube will have a mixture of hydrochloric acid, ferric chloride and other assorted gunk in it. If you have no other way to dispose of it, you can neutralize it with lye which turns it into the equivlent of rusty salt water with a little additional crud in it. Baking soda will also neutralize it.

WayneJ

Ive used battery acid successfully, Follow the pre acid preperation as above. I put the files in the acid on their edges at an angle so that the cutting edges on the face sides are vertical. This is because the gasses from the acid reaction causes an acid circulation up the file surface . It works best if they are orientated this way. I find you need to check threm catrefully every half hour or so. If you leave them in too long all the teeth will have gone!!. Ted in Dorset UK

Excellent! Thanks Wayne. Well presented.

Gunner

"Not so old as to need virgins to excite him, nor old enough to have the patience to teach one."

Thanks Ted.

Gunner

"Not so old as to need virgins to excite him, nor old enough to have the patience to teach one."

Cheap files have generally worked pretty well for me, except for lathe filing. The "Globemaster" mill file I bought in ~1965 has finally dulled in the middle but the ends are good. The Nicholson from a 1978 motorcycle journey still cuts like new. Those are the two I always grab for deburring, to keep the more specialized ones sharp longer.

Heatshrink sleeving protects them well in a toolbox.

jw

On Sun, 08 Feb 2009 17:12:36 -0800, the infamous Gunner Asch scrawled the following:

Guys on the Wreck used to talk about that, but most went to Boggs, including Steve Knight, the planemaker who goes through files like we do potato chips. The Weygers way was via battery acid.

You makin' scrapers, boy?

-- If we all did the things we are capable of doing, we would literally astound ourselves. -- Thomas A. Edison

Dovetail files for fitting sights into firearms dovetails.

Gunner

"Not so old as to need virgins to excite him, nor old enough to have the patience to teach one."

After years of working under my uncles' tutelage imagine my surprise when I found out that there were companies in existence that actually made NEW files! I was used to using files that were so smooth they wouldn't actually leave a mark on mild steel. When I started buying files I went for good ones and took care of them. I remember finding out about chalk! Over the years, I've made a number of tools from those old files from my youth.

They are dull because their worn out, Gunner. Buy her new files as she needs them - for making a drill gauge, a bastard, 2nd cut, and smoothing will do it. And you only need the small sizes for this job. Buy them as needed....

DON'T give her crap, worn out tools - she wont know the difference between good and bad as she has no experience, and will forever think that files are useless except for opening paint tins.

Andrew VK3BFA.

Yep, thats the way it is - glad someone has used a new file and knows the difference.....

Andrew VK3BFA

Aren't many modern files case hardened? Would the acid etch through? Karl

On Sun, 8 Feb 2009 22:48:49 -0500 in rec.crafts.metalworking, "Ed Huntress" wrote,

There is a drawing of it in Leonardo da Vinci's notes.

If you want to keep her as a lady friend, get her new ones. Boggs has worked well for me, but others tell me that you can only do it once. So, if you already know about Boggs, how do you know that some or all of the dull files you have haven't already been there? A friend of mine who goes through a lot of files does use Boggs, but he files a mark on the tang to tell him that it has already been through their process.

Pete Stanaitis

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Gunner Asch wrote:

Excellent point.

At one time, I had even more files, the vast majority being new, or near new. Id been collecting them from swap meets/auctions etc to make knives out of. Then a buddy brought over his brother in law, who wanted 'a few files" and I told him to take what he wanted. He snagged damned near all of the new ones..about 20ish, while my buddy and I were chatting about an ongoing project.

And I didnt have any Chinese ones....sigh

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Bill Clinton 1993-08-12