Under the Choko Tree By Nevin Sweeney

Hand Tools - Files and Rasps

Thirty years ago and old friend of mine by the name of Bill Tarplee was operating a magazine out of Canberra and he wrote a series of articles on buying, doing up and looking after hand tools. Bill was a manual arts teacher at one stage, very skilful with his hands and knows all that there is to know about hand tools (among other things). I have been lucky enough to secure his permission to republish some of his original articles (this one was originally published in January 1984) and is the last in this series.

Please note: I have done my best to reproduce the "cuts" that Bill used as his illustrations but I am dependant upon the quality of the original printing, which was somewhat variable.

Of all hand tools, files must surely be the most varied. For each trade certain files have been adapted to certain requirements. Thus gunsmiths developed files that differ from those used by engineers or clockmakers. While this may cause some confusion at times it does mean that one can find to suit almost any purpose.

In the past when looking at tools I have recommended the purchase of second hand tools wherever possible. This is an exception to that rule. I have rarely ever found any good second hand files, and wouldn’t waste my money. New ones are chap to buy and you wouldn’t be saving much.

Flat files are the most widely used by the average home handyperson. They come in two basic forms and three basic grades. To amplify upon that statement:

Teeth may be cut as shown in the illustration below. Here we have a single cut file. The teeth are cut at an angle to the edge, and are parallel for the full length of the body.



Below is a double cut file. In this instance a second set of teeth have been cut at an opposing angle. This produces diamond shaped teeth.



The number and depth of the teeth will fit into three grades. Where teeth are large and coarse, the file is a “bastard” file. When somewhat finer, it is a “second cut” file. When fine and close together the file is a “Smooth”. These grades may be found on files from about 15cm up to about 60cm long.

In addition you can buy files that are smooth along an edge (safe edge) or even a face. When toothed, an edge may be either flat or curved. As I said before, each trade has developed special purpose tools.

In addition to the normal flat or hand files, one can buy half round files (flat on one side, curved on the other), square files (square in section), round (or rat tail), these may taper as in a rat tail or be parallel for sharpening chain saws or triangular (triangular in section – as in a saw sharpening file). There are also combinations and variations to these basic shapes. You may find oval shaped files, diamond shapes etc.



To use a file properly is not difficult, but it takes care and thought. Files should only be pushed across the work. To pull a file back across the job will only hasten the wear on the teeth. Thus on should work slowly and methodically; push the file across, lift on the backstroke. Try and adopt a mechanical stroke of even steady rhythm. This is far more productive than frantic sawing at the workface. Use sufficient pressure on the tool to make it cut into the work. A file that slides across the job will soon dull and there is nothing more useless.

Never try to file metal that is too hard. If the file won’t bite, look for another way – maybe grinding? Files are extremely hard but soon will become dull. This then leads to a very good rule: If you can, keep new files for working brass. This metal requires a very sharp file. When it eventually dulls (and it will), then use it on steel. It will still be sharp enough for steel when it no longer cuts brass. One little trick of mine is to paint the end of one side. Keep the painted side uppermost until it dulls, then turn it over. This keeps one side keen for brass, and seems to prolong the working life of the tool.



Files can clog up when working on almost any metal. Clogging is called “pinning”, and will quickly cut deep scores along the work face. There are special cleaning brushes called file cards, which are used for unpinning a file. Being made from a hard steel they soon dull the teeth. I prefer to use a soft piece of metal which I pull along the line of the teeth. Alternatively you can use a bronze suede shoe brush to good effect.

Another trick is to rub a piece of blackboard chalk along the teeth. The chalk prevents the metal shavings from wedging in, but it also slows down the cutting somewhat. You can help prevent pinning in round files by rotating the file as you push. You can sometimes prevent it with hand files by changing the angle of the stroke.


Ideally one would commence a job using a bastard file, then switch to a second cut for cleaning up, and finish with a smoothing. Since you may not have a wide range to choose from, you can try draw filing to give a smoother finish.

To rough down, you usually file across the work. Draw filing is when you hold the file at both ends and draw it along the work. It is effective but can cause pinning so do it with care, and check the file frequently. Also, using chalk will slow the cut and give a finer finish.

If you have the opportunity, buy as many different files as you can. Also, never pass up the really big files if you can afford them. The longer the file, the quicker and easier it is to use. I’d far prefer a 50cm file over a 25cm file, all else being equal. They are easier to use and the extra length makes cutting much faster. Once you get used to a long file, you won’t go back to the shorter ones for general work.

There days one finds uncommon files in the shops. I’ve found some really large and unusual ones recently, and they were well worth the purchase.



The illustration above shows and dreadnought file.  These are suitable for both some materials such as brass and aluminium , and wood. Aluminium is particularly prone to clog files, and the tooth shape of the dreadnaught is a method of countering this. These files are also suitable for working plastics – particularly body filler and soft solder –, both of which are used in panel beating.

Another attempt to prevent clogging is the millencut, as shown below. Again this may be regarded as a transitional tool, being equally suited for soft metals as well as wood.



Files used in woodwork are called “rasps”. Mostly they have individual pointed teeth as shown below left. They should never be used on any hard metal. The teeth will not stand up to that sort of abuse.



Because of the tooth shape and the differing characteristics of wood, rasps have very little tendency to clog. The only problem I’ve has been with a resinous timber. A bronze suede brush will soon fix that. If that doesn’t clean up all the teeth, brush on a coat of mineral turps. That dissolves the resin.

While it is pretty much a last ditch remedy, you can resharpen files. The first step is to give the file a thorough cleaning, taking care to remove all grease as well as dirt and pinnings.

Pour a small amount of sulphuric acid into a plastic bottle top, and put both acid and file into a large plastic bag. The bag should be propped up to form an enclosed tent. After several hours the acid fume will have etched away the surface of the file and given it a red coat of rust. The file should be liberally wished with water and a paste of garden lime and water applied to the whole file. The lime will neutralise the acid. Wash off the lime and brush away any remaining rust before drying the file in the sun. Apply a coating of oil to the body of the file to prevent further rusting. After a day or two the oil can be removed and the file is ready for use again.

Oil on the file will prevent rusting but it also helps to increase pinning. I like to keep files oil free unless I have a particular requirement. After that, I wash off the oil and keep the file dry again. When draw filing you can rub chalk onto the body and put a couple of drops of oil on the chalk. This will give a very fine finish, but pinning could be a problem. Some metals are far worse than others, so try it and see what results you can obtain. At worst you can easily brush the chalk out and wipe the metal clean.

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