In the World of cutting tools, there is no more primitive example of tools still in wide use today than the lowly hand file. Relied upon since the stone age, the first recording coming from the time of King Saul, about 1090 BC! Files were the tool of choice to smooth, hone, clean and debur all kinds of materials.
Leonardo DaVinci was the first to attempt to make files by machine, a practise that was eventually perfected in 1750 by Frenchman Chopital. At this time, files were made of soft iron and put through through various processes to harden or carburize the teeth.
Through the later efforts of men such as Bernot, Nicholson, Whipple and Weed, machine made files developed to the point where they were better than those produced by hand. Today, there are dozens of manufacturers making a full range of files for both general and specific applications.
Hand File Anatomy 101
There are several parts that make up a file. First, there is the TANG. This is the pointy end and is used to attach a wood or plastic handle. Some files come with handles already integrated or moulded over the tang while on others, like a Farmer’s File, the tang has been flattened and widened to form a handle as part of the chisel.
At the base of the tang is the HEEL. This is where the actual body of the file begins.
The next section is the area where all the cutting action happens. This called the BELLY of the file. Some files cut from all edges, some have edges that are smooth. Some edges are flat, some tapered and some are even rounded. You can even get files where the two opposing edges are different.
At the end farthest from the tang is the POINT. Strangely enough, this can often be quite square or anything but pointed, but it is in fact, the end you ‘point’ at the work you are going to be filing.
A file’s size or LENGTH is measured from the base of the HEEL, to the end of the POINT. The length of the tang or handle, is not considered part of the length.
The Cutting Edges
Most American Pattern files are available in three grades of cut. Bastard, Second Cut and Smooth. The length of the file also affects the coarseness, regardless of the actual grade. So for example a 6″ Bastard Cut is a lot finer than a 12″ Bastard Cut. This is because the shorter files are generally used for finer work. Overall, the least coarse would be a 4″ Smooth file and the most coarse would be a 16″ Bastard file. The relationship between the grades of coarseness for each length remains the same.
Swiss Pattern files on the other hand, come in seven grades of cut, from ØØ to No. 6 where the ØØ represents the coarsest and 6 the finest cut. These files are used for detailed work such as by jewelers, watchmakers, model makers and tool and die makers.
Choosing The Right File
There are numerous types, sizes and purposes for files but generally speaking, they fall into one of the following categories. Within each of these categories there are a number of standard variations, each with a particular design. Now, you don’t have to use them for these purposes only —whatever works in a given application. However, from an information point of view, here’s how they break down.
Machinist’s Tool Files
Generally Machinist’s Files are Double Cut for rapid and maximum stock removal. They are also probably the best known as they’re used in numerous applications and on most metals. Machinist’s files are available in Bastard, Smooth and Second Cut.
Saw Sharpening FIles
Saw files are usually of the single cut type for a smoother finish. They are suited to sharpening saws and dressing tool edges where a finer, sharper edge or smoother surface finish is desired.
Special Purpose Files
These are file-like tools that have been developed over time for specific applications or materials. Examples of Special Purpose files would be wood rasps, foam files and body filler files. Shape, tooth pattern and other material-specific criteria determine the optimum use for these file types.
Swiss Pattern Files
If you do superfine or precision filing —particularly in the tool and die, jewelry and model making professions, Swiss Pattern files are recommended because of their small size and finer width and thickness. Made to more exacting measurements than American Pattern files they are available in a wider range of finer cuts with teeth that extend all the way to the edge and fine points for getting into tight areas. Swiss pattern files are generally between 3″ and 6″ long.
Swiss Pattern Riffler Files
Somewhat resembling your dentist’s tools, Riffler files are designed so that the middle sections are uncut, making them safe for comfortable handling. They have slender, narrow ends to facilitate fine detail work.There are two types of Riffler files, each available in 12 different, distinct patterns.
Die-Sinker Rifflers tend to be smaller and finer and are primarily the tools of die-sinkers, jewelers and instrument makers. Silversmith Rifflers have longer middle sections and wider ends than Die-Sinker files.
Swiss Pattern Needle Files
Of the Swiss Pattern files, Needle files have a double cut pattern. Used by jewelers, die makers and other detail craftsmen, Needle files come in 12 different shapes and feature a long, knurled handle. Because of their diminutive size, some Needle files have integrated plastic handles to decrease finger cramping, cuts and abrasions.
Filing is an industrial art. It’s not about simply rubbing the file back and forth on the material, every stroke should count and move you one step closer to a smooth, polished finish, without gouges or abrasion marks. There are three elemental filing techniques.
Straight Filing is done by pushing the file lengthwise down the workpiece in a straight-ahead or slightly diagonal position. The cutting stroke is the push stroke. Done correctly, the return stroke doesn’t even really touch the workpiece. Straight filing can be used for maximum material removal or smooth final finish.
The nature of the material sometimes makes straight filing difficult. or awkward. Drawfiling is another popular filing method. This is accomplished by grasping the file at both the handle and the tip and pulling it across the workpiece towards you. Draw filing can also be used for maximum material removal or a smooth finish.
The third method is Lathefiling and just as the name implies, is the process of stroking the file against a workpiece that is revolving in a lathe. This can be useful when truing a work piece of for material removal. As with any application involving your hands and face and revolving tools, this should only be done with much care and attention.
Proper File Care & Feeding
There are a number of simple practises to make your files last near to forever.
Keep the pressure off. Apply only enough pressure to allow the file to do the work. You should feel the teeth biting into the workpiece and the movement should be fluid and smooth. Applying the correct pressure will also result in the fastest removal of material, even if it takes a few more strokes to get the job done. Soft material such as aluminum has a propensity to clog cutting teeth, even though there is a specific file designed for it.
Protect Your Teeth. File teeth should be protected when not in use. Tossing them in with all your metal tools is not a good idea! Ideally, they should be hung or put in a drawer with non-metallic dividers and with enough room for them to fit without a lot of contact. It should also go without saying that files should be kept free and clear of water, dirt, grease and filings.
Keep It Clean & Clear. If you’ve got files, make sure you’ve also got a file card and use it during and after you use a file. A file card has rows of small, stiff wire that is used against the file teeth to clean out the debris. Filing creates heat and the small particles it removes are sharp. Cleaning by hand can get you a cool metal sliver in your finger, using a card clears it away quick and before it can get stuck in the fine grooves of a file.
Filing Different Metals
Metals vary greatly in properties and the nature of the metal has to be taken into account when choosing the right file for the job. Soft, ductile metal requires a keen edge with only soft pressure whereas a harder material would require duller teeth and more pressure.
Filing Stainless – Tough, dense and abrasive, stainless steel requires a file which has good wearing qualities and requires light pressure and a slow, steady stroke.
Filing Aluminum – Soft and difficult to file, the challenge is to prevent the teeth from clogging. A special cutting edge has been developed with a deep, open throat upcut and a finer overcut which breaks up the filings, prevents taking too large a bite and helps to overcomes chattering. Use a shearing stroke to the left for the best finish.
Filing Brass – Brass can be difficult because it is softer than steel, but tougher and harder than aluminum. Filing Brass requires a file that has sharp, sturdy teeth and a cut that prevents grooving and running the file off the sheet. Brass suited files have a short upcut angle and a fine, long overcut to keep the file clear of filings. Moderate pressure produces a deep bite from the high-cut teeth while less pressure produces a smooth cut from the short, uncut teeth.
Filing Lead – Wear a Respirator! Soft materials such as lead, babbitt and copper present distinct filing conditions. It requires a file with short, single cut and stubby teeth which shear metal under normal pressure.
Filing Bronze – SImilar in nature to brass but dependent on the content of alloying elements. The harder a bronze, the more acute angle at the top of the tooth. This is known as thin-topped teeth. The direction of the cutting stroke should be crossed frequently to avoid grooving.
Filing Wrought Iron – Relatively simple, wrought iron is soft and ductile and does not require a very sharp file for good results.
Filing Plastic – Hard plastic requires a file with high, sharp teeth. Soft plastics are filed in shreds, so a shear tooth file should be used in this application as well as other soft materials like aluminum, copper, hard rubber and wood.
File Identification Chart
Here’s another handy chart you can download to give you an overview of the various types of files, their purposes and profiles.