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FILING 101

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Zonie

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Many of you already know the subject of this post however there are many out there who decided that there are more girls in the Typing Class than there are in the Shop classes. Others had the misfortune of being in one of our new schools where such mundane subjects as Wood Shop, Metal Shop, Drafting and Auto Shop are not even offered. It is for these people I am writing this.

FILES
While everyone seems to know what a file is, most don't know what kind of files are available. I will stick to the ones most commonly used when working/building rifles.

There are several shapes of what most people think of as a common flat file. The names of these are WARDING, MILL, FLAT and HAND. They are all similar but the Warding is rather thin and the Hand is fairly thick. The others are in between in the order listed. The other difference is the first four are tapered while the hand file edges are parallel.
The Hand file has one or more "safe" edges meaning the edge doesn't have teeth. This is handy when you want to file up to a surface but you do not want to cut into it.

Other files:
There are triangular, square, round straight, rat-tail, knife, and dozens if not hundreds of other file shapes but the only ones important to most gun makers are the flat, triangular (three-square), square, round and maybe the knife.

I am not covering rasps but they are similar to the above files except they have individual punched teeth and are made for cutting wood.

The TOOTH STYLE can be summed up as either a Single-Cut or a Double-Cut.
As the names describe, the single cut has one set of teeth running diagonally across its face. These produce the smoothest finish of the two styles. They are also rather slow cutting.
The Double-Cut has two sets of teeth crossing one another. This gives a diamond appearance to the files face. This style as you might guess cuts much faster than the Single-Cut but leaves a much rougher surface.

TOOTH SPACING Listed from the roughest to the smoothest, the tooth spacing names are: ROUGH, COARSE, BASTARD, SECOND-CUT, SMOOTH and DEAD SMOOTH. The commonly available files at the Hardware store are the Bastard, Second-Cut and Smooth.
If given only two to choose from I would take the Bastard and the Smooth as these can do about anything I need to do when working on Muzzle-Loading guns.

It also reminds me of the story of the man wanting to buy a file. The owner of the Hardware store asked if he could help and the man said he needed a file. The owner said "will I have this nice Bastard file here." The man, not wanting to look ignorant replied, "No, I think I'll take that Son of a gripe over there."

The TANG: Beware the Tang!! Some feel they don't need a handle on their files but IMO their fooling themselves. A handle driven down over the tang not only protects you from getting stabbed but serves to help you control the way the file removes material. If you don't want to buy a handle, then buy a 3/4 or 1 inch dowel rod, cut it off, drill a hole in the center and drive it onto the tang. You will be glad you did.

FILING: Everyone seems to know how to file, but more files are worn out by these people than by cutting material.
Say, what?? Most people just rub the file forward and backwards over the metal, pushing down as hard as they can and going as fast as their arms can go. This is a sure way to wear the files teeth out.
Things to think about:

1.The file must be harder than the material you want to cut. Don't file "really hard" materials. Grind them.

2.The file ONLY cuts on the forward stroke. Lift the file or at least remove all downward pressure when pulling the file back across the work.

3.The act of cutting actually melts the material being cut, and this heat can remove the hardness of the files teeth. The faster you file the worse the effects of this are. Take slow strokes without stopping in mid stroke.

4. Dragging the file tooth backwards over the metal will dull the files teeth. (See #2).

5. Dirt in the files teeth will grind the tooths sharp cutting edge off of the file if you use it in that condition. It will not "self clean" without damaging itself.

6. If filings remain in the files teeth, it cannot cut well. If you don't have a File Card (a little pad with wires sticking out of it used to clean the file) buy a little brass wire brush. I've seen these as cheap as 50 cents and worth every penny.

7. A light dusting of chalk can help keep the teeth clean when cutting gummy material like brass but it, like dust can take its toll on the files sharpness if overused.

8. Do not use Oil when filing. Oil on the file or work will make it "skip". In doing so the speed will increase and the files teeth will overheat on their first bite. (See #3).

9. Use moderate, even down pressure on the forward stroke. Heavy pressure increases the heat from cutting and places un-called for stresses in the teeth which will result in dulling them. Heavy pressure also makes controling the file much more difficult which in turn increases the likelyhood of you making an error.
Using Light pressure will cause the file to "Skip"(See #8).
When filing use only enough downward pressure so that the file is taking a good smooth bite on the work. You will be able to feel it working with your hands. I cannot describe the feeling. (Boy, there is a opening but this is a family show).

10. All files are really hard. This makes them brittle so don't use them to pry with. Also, because they are all equally hard, they can damage each other if you just throw them into a drawer. Store them in a way that keeps them clean and keeps them from banging into each other.

DRAW FILING
A technique used for smoothing the work surface.
Often this is done on the barrel flats to remove the grind or mill marks left by the barrel maker.
Although the Mill File with "Smooth" teeth is recommended, (no, not worn out. Smooth, remember from up above?) any flat file will work but don't use a Double Cut file and use the finest teeth file available to you.
I prefer files with the small edges made "safe" (without teeth) to keep from accidently making scratches when I'm Draw filing. You can grind off the teeth on your file if you wish to have a "safe edge".

A light coat of your kids chalk will help keep the files teeth clean while you do this process.
With the work going away from you, hold the file across the work at about 90 degrees to the direction you wish to cut.
The Tang should be on your right*. With the tang on your right, the file will cut as you push it away from you.
Because it is at 90 degrees to the direction of the cut it will make very smooth cuts however the filings won't be able to escape from the teeth. Because of this, it is recommended that after each cut or stroke, brush the teeth to remove the chips (or at least tap the file on a piece of wood several times to knock out the filings). Failure to do this will cause the filings to gall. Galling is when the filings weld themselves to the work and then tear loose leaving an ugly scar or scratch.
It goes without saying you should think only of keeping the file level to keep from rounding off the flats you are trying to smooth and concentrate on making long, smooth strokes.
Rotate the barrel to the next flat when you want to work on it. You should only work on the "top" flat. Do not try to set the file at an angle to the workbench and work on another flat or you will have more than your fair share of problems.

Filing is perhaps the most used process in building a black-powder rifle. Buy the BEST files you can find and afford. Treat them with the care all fine tools deserve. This especially means keep them away from your kids (and others who don't know all the things you now know about files).

* Some prefer to have the tang on the left. If you use the file in this position, the file will cut while you pull the it towards you.

If you have made it to here, give yourself 1/2 Credit hour and go pop a top! You've earned it.
 
Excellent post. Very informative and well-written. Thank you. I've often wondered how a file is manufactured. How was this done historically. I am a bowyer and farrier's files are part of my tool kit. I've heard it told in the bowbuilding circle that you can bring some life back to your farriers files by briefly laying them in a bath of muratic or similar acid. I have never had a reason to try this, but what do you think? What more can you share about these topics?
 
I have heard of the Acid bath treatment using a number of different acids from Muratic Swimming Pool acid (hydrochloric) thru auto battery acid (sulphuric) to Nitric acid. I have the same opinion of all of them. Don't do it.

My reason for saying don't do it is because the acid will attack the surface of the steel. It isn't picky so it eats the front (cutting surface) and the flank of the tooth equally. It desolves sharp edges even faster.

Where the cutting edge is, the front and flank should form a sharp edge where they meet, but the sharp edge is being attacked from both sides by the acid at the same time. It is also the place with the least material. This means the sharp edge is the first thing to be dissolved leaving a blunt edge.
When you stop and think about it, if the edge is dull, why would the acid attack the face and the flank of the tooth and decide to leave a little sharp edge where they meet behind? IMO a file with a dull edge will just have the dull edge made duller by soaking it in acid.

Acid is in fact used to deburr or dull the edges of fragile metal objects because it does not apply any pressure which may distort or destroy the part and although it attacks the other surfaces as well, the effects are minimal. (You can design the extra material into the pre etched part so its loss is of no consequence.)

There is a process which is claimed to be able to sharpen files. This process uses "liquid honeing" and although I don't know how good the companys who offer it are, the theory is based on this idea:

If you suspend abrasives in a fluid and then direct that fluid under very high pressure at the flank (non cutting back face) surface of the tooth in a direction which is the same as the direction you would push the file when filing something, it will wear the flank away.
As it is only hitting the flank side, as the tooth wears it will leave a sharp edge where the flank meets the face of the tooth.
This can be thought of as lapping or honing only on the angular face of a chisel. As you remove material, the edge which is formed where the angular face meets the flat back of the chisel will become very sharp.
The process cannot increase the tooth depth so IMO it would not be very effective on a badly worn file.

Check out the post by Boggs for more discussion on this subject. He is trying to sell a service but it sounds interesting.
 
Homemade file handles, 3/4 dowel because you can burn the plastic outta a 12 ga shotshell to use for a ferrule.

I've seen files get caught on a lathe and imbed themselves in the human hand when a straight tang is used. Some bent the soft tang into a hook as a precaution.
 
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