This article is about key notes and tips for your files for jewelry making, how to take care of them and how to handle them properly.
When one gets a new file one traditionally dips it in alcohol and sets fire to it to burn off any grease (this could be dangerous-use great care). Get the longest files you are comfortable with as the long stroke is very efficient. 20 cm or longer needle files from Germany are my favorite and hand files too may be more efficient if longer. One usually needs to cut off the back quarter or third of the tang using a standard jewelers sawblade so as to be able to seat it closely enough into the handle.
The method for seating the file is the same as for installing an engraving tool into a handle. To seat the file one clamps it close to the tang in a vise, heats up the tang with a torch reflected off a fire brick held behind the tang until it is red hot and then accurately, rapidly and carefully pushes the file handle onto the glowing tang. This burns a square hole, otherwise impossible to obtain. When pushing the handle on hold it steady in order to push vertically and avoid a crooked handle. It is also important to blow the smoke generated away hard as it can catch fire around ones hand if it gathers.
Be careful when burning in a handle like this not to push a red hot tang through the back of the handle into the palm of your hand. When you push it down do not push it too far down onto the tang. Leave about 1 cm to go before the handle butts up against the shoulders of the file. All this is done quickly and the handle rapidly jerked back off the tang as soon as it is to the correct depth. This is to prevent the tang burning the hole out sideways as well as into the handle and would mean a loose fitting handle. After jerking the handle off let the tang cool a moment or cool it with a wet sponge and then hammer or mallet the handle down to the shoulders of the file. This seats the file in close to the handle and makes for a better hold on it when it is in use. File handles with a burned in yet tight square hole can be pulled off and exchanged for other files if needed. You will need good ventilation as a lot of smoke is generated in this procedure.
Remember that a sawblade is nothing but a thin slice out of a file and a file is just a fat sawblade. Sawblades can be used like miniature files and traditional azure sawing, an angled square bevel into the backs of stonesettings is done using the sawblade in this manner.
I recommend 20 cm long .i.needle files; from Fischer in Germany. The long stroke is great. If you do not buy the entire set then buy square, triangular, round and half round. These should suffice for most. My personal favorite is the triangular file for most of the work I do with needle files.
Files may apparently be re-sharpened by a treatment with nitric acid. However one should use dilute acid as a strong solution tends to attack the tops of the teeth first thus blunting the file further. A weak solution will attack everything more evenly thus thinning out and ‘sharpening’ the tops of the teeth. Remember to use goggles, gloves and ventilation.
Some people rub a file with chalk occasionally to help prevent its teeth clogging. One might try machinists silicone dry lubricant as well.
If a files teeth are clogged besides using a file card for .i.cleaning files; one can take a small piece of brass or nickel silver sheet and slide it in the direction of the teeth thus pushing out any material clogging them. One cleans the file sweep by sweep going down it pushing out stuck material with the sheet.
Files; may be bent into any shape needed by heating to red heat and bending with a wooden mallet. They are then rehardened. This is a relatively cheap way of getting some of the simple riffle file shapes though they are not as good as purchased ones. There are expensive riffle files available but their real applicability dates from a not too distant time when steel blocks were carved, chased and finished for stamping jewellery parts out of. One can also buy bendable needle files which are quite expensive and mostly good for the thrill of being able to magically bend steel with your fingers. Riffle files to my mind are not very useful most of the time.
A file should have a handle as otherwise you can ram the tang into your hand.
A file should be cleaned regularly.
One should file rhythmically and regularly for best results. One should keep it on the work most of the time one is using it. This develops a good feel for what the tool is doing and is more efficient in use. Though the file is used up more rapidly any losses in file cost are more than made up for by speed and efficiency of filing. Only when doing very fine finishing work does one lift the file from the work. The Benchmate ® allows one to clamp jewellery for two handed filing.
Large work should be approximately elbow height when using large files.
For heavy filing, the thumb is up on the handle, the palm of the other hand on the end of the file, the fingers curling under the end, or opened slightly.
For finer work with two handed filing the hand on the handle remains the same, the one on the end of the file is reversed so that the thumb rests on top (guiding), and the fingers curled below lightly gripping the end of the file.
Cross the stroke fairly regularly to check the trueness of your filing. Sighting down the length of the work and checking with a square is also useful. After a time sighting for trueness becomes automatic and the only necessary checking.
t is hard to learn to file to perfect angles and so on. Use checking tools like a ruler or steel edge and a try square to see how your control is doing. Like all hand tools control is best learned by holding the handle very tightly in your hand when using it, after a few moments the hand relaxes but one retains some memory of the extra control one had when it was tightly held. By repeating this tightness and relaxing one’s control of a hand tool whether a file, graver, flex shaft handpiece and so on will rapidly increase.
File relatively slowly and check the work often.
Use a new file gently until it is worn in a bit, hard use will clog it badly.
Lay a file down carefully, not banged down or banging and rubbing against other files-it dulls them. Kitchen knife magnetic strips are nice. I use a board with round holes drilled in it for my files. They slide into it up to their handles.
Stance is important, standing .i.filing ;becomes almost a dance if done correctly. A suggested stance: “left foot pointing towards bench (or vise), the hollow of the right foot 8 to 12 inches from the left heel, and bend the body slightly forward at the hips. Hold the file as in with the right arm bent to about 90 degrees and the left arm somewhat nearer straight. Lean forwards slowly for about two thirds of the stroke, bending the knees slightly, and at the same time, push with the arms. During the last third of the stroke keep pushing with the arms but bring the body back slightly to nearly the original position. Then bring the file back lightly on the work to position for another stroke. Work slowly, bear down reasonably hard and keep the file level.” from Machine Tool Operation: Lathe, Bench and Forge, by Henry Burghardt, McGraw Hill.
When keeping the file on the work on the return stroke, release the pressure while returning so the file slides easily towards you but is still in tight intimate contact with the metal surface.
One can make an interesting .i.combination scoring tool and file; by taking the end of the appropriate needle file (triangular or square for instance), breaking it off and then grinding it so it acts like an engraving tool if tipped slightly. One can then tip the file slightly while filing and use it for scoring without needing to pick up and put down a tool; the file is both graver and file simultaneously.
Needle files with teeth on one side and a smooth peaked triangular back may be ground off until there remains a thin file with teeth on it. It must be cooled constantly while grinding so as not to lose its temper. The ground off area on the back is emeried and polished and as there is barely any metal left other than that required to maintain the teeth it becomes not only very thin but flexible as well. The file is extremely useful for getting into tight places such as stonesettings and during catch building. The polished flat back of the file serves to burnish the narrow spaces it is intended for while using it.
Wax workers like Gary .i. McMillan insist on using only new files for working in wax to gain maximum sharpness. The files are not used on metal to avoid dulling them.
Because file steel is very good high-carbon steel old files are always useful for something, whether scrapers, burnishers, stone setting tools, drawplates, knife blanks or whatever. Careful grinding keeping the steel cool to keep it from losing it’s temper is far preferable to annealing the steel and then having to re-temper it.