The Use of Tools : Files, Chisels and Scrapers.
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Contributed by an Engineer-in-Charge.
In the following article I shall endeavour to give plain instructions regarding the use of the various tools which are indispensable for the execution ot ordinary running repairs to motor vehicles. These instructions apply more especially to drivers of steam wagons and tractors, although they will also be of benefit to drivers of petrol vehicles. The tools are neither numerous nor expensive, and will not involve the outlay of more than tela, which is a very small item, in comparison with the saving of lost journeys and delays on the road which in many instances could be avoided if the driver was supplied with a few tools to enable him to carry out the necessary repairs.
It is advisable that the wagon should be kept under cnver in some suitable building, well lighted and drained, with a good substantial bench, a good vice, and a lock-up box in whim to keep the tools: such provision will offer great inducements to a man to undertake small repairs.
Many a time a wagon is run into a local engineer's shop for some trivial job that could easily be done by the driver, a.though, on the other hand, it is not to he supposed that a man can undertake all the repairs that are likely to be required, or save an occasional overhaul; but it will go a long way towards minimising the prejudice that exists against vans and wagons, due to the fact that some are continually being laid up. The tools required are: various files and chisels ; stocks; dies
and taps (for screwing and s3,of an inch); ratchet brace and drills ; drilling pillar ; hacksaw ; grindstone ; two, 21 ton, lifting jacks ; one 5-inch jaw, leg vice; one parallel vice ; and a small .portable forge and an anvil. The files and chisels are in constant demand, and the correct manner of using them is only acquired by experience: to watch an experienced man using a file, the operation looks very simple, but, in reality, there is more in it than is apparent at first sight. It is impossible to give written instructions to a man how to file square and flat, although a few practical hints, coupled with a deal of practice, will enable him to use a file properly. Files are made in various sizes, grades, and lengths, to suit any requirements, but the files in most general use are of the flat (A), half round (13l, round (C), and square (1)) types, all of which are shown in Fig. 1. . They are made tapered or parallel, and one edge is often left plain in the flat and square files, and is called a "sate edge " ;. they are named " smooth," " second cut," and " bastard," according to the fineness of the teeth. A smooth file is used for finishing work ; a bastard file is used for rough filing.
The position of the vice is very important ; in the first place, it should be fixed securely, as it is impossible to file accurately if the vice is not steady. The height of the vice jaws from the ground should be about the same height as the user's elbow, and the light all round should be unobstructed so that the work can be readily examined and tested by the aid of a square and a straight-edge.
Castings, as received from the foundry, are covered with a hard, outer skin which must be removed before a good file is used on it ; otherwise the file teeth are dulled in a moment. Any old file will serve to remove this skin and expose the softer metal underneath ; the same remarks apply to forgings, the black scale which is on these when they leave the fire will ruin a new file, and it should he removed by an old one. A new file should he used for brass and gun-metal first, arid, as soon as it is too dull for this, it can be used for cast iron, then for wrought iron and, finally, for steel ; if a new file is 'first used on steel it will not he much good for the softer metals afterwards. Be.
fore commencing to file, the work should be gripped firmly in the vice and the file handle securely driven on to the tang; otherwise, when filing, if the handle comes off, the hand may be damaged by contact with the point of the tang. The file should be held with the palm of the left hand laid across its end and the fingers holding it underneath ; the palm of the right hand should be laid lengthways of the handle, and the thumb should point towards the end of the file, the remaining fingers gripping underneath the handle ; the feet should be about 2 feet apart, so that the whole weight of the upper part of the body can be thrown on the file, and can move in unison with it.
The greatest trouble experienced in filing is to obtain a fiat surface on narrow work, owing to the varying leverage which is exerted on the file: at the commencement of the stroke, all the leverage is on the handle and tends to force it down ; on the completion of the stroke, the leverage is transferred to the end of the file, the change tending to produce a rounded surface. It is the avoidance of this result that constitutes the art of filing. The pressure on the file end anti handle should be varied, starting with the least amount of pressure on the handle at the commencement of the stroke, and gradually increasing it until the stroke is completed ; at the same time, the pressure on the point of the file should be gradually decreased. On the return stroke, the file should be lifted off the work, as the teeth do riot cut during this stroke ; the file is, however, generally drawn back while resting on the work, bu,t the pressure of the hands is released.
The work should be frequently tested with the straight-edge or square, and, if high places are discovered, these should be filed in a different direction, by crossing the file marks. If the filing is being done from the left-hand side of the vice towards the right, the high places can be filed from right to left, and it is then easily seen how the file is cutting. An experienced man can tell exactly how he is filing and only uses the square or straight-edge when the filing is nearly finished. After one face has been worked up nice and flat, the other faces should be worked up from this one, using the calipers to test it for parallel. In filing wrought iron, especially along the grain, particles of the metal are liable to become imbedded in the teeth and to produce deep scratches ; this is overcome by rubbing the file over with a piece of chalk, which prevents the file " priming." Cast iron and gun-metal are not addicted to this fault. If a file becomes dirty, or greasy, it can be cleaned with a piece of "file card."
Chipping does not present so many difficulties as filing, but a lot of practice is required before efficiency is attained: if too much is taken off, the face cannot be filed up without leaving "witnesses,'' whilst if too much metal is left on, a lot of filing is required to bring it down to the required dimensions. Chisels should be ground to an angle of about .55 degrees, and the corners should be slightly rounded, to prevent them getting knocked off ; they should be drawn out fairly thin, about inches overall, and should be tempered to a light purple colour. The chisel should be held in the left hand, close to its head ; better control over the chisel is obtained by holding it in this position than if it is held in the centre. The depth of the cut is regulated by the angle of the chisel with the work. The head should be well raised for a deep cut, or lowered if a shallow cut is to be made. A casting should never be chipped -right
up to the edge: the chipping should always be away from the edge, otherwise it is liable to break away. It is a good plan, when chipping plain surfaoes, to scribe a line round the outside edges and chamfer them down to the scribed hues, which will serve as guides for the amount of metal that has to be removed, besides reducing the danger of breaking particles off the edges. When chipping wrought iron or steel, the edge of the chisel should be dipped occasionally into a small pad of cotton waste which has been saturated with oil; this will greatly assist the cutting action. For chipping cast iron, lubrication is not necessary.
The chisels in most general use are shown in Fig. 2. That marked A is the ordinary cold or " chipping " chisel, and this type varies in width ITOM • inch to 1 inch. B is a " cross-cut " chisel, used for cutting keyways in shafts or pulleys (when these are done by hand) ; this chisel is slightly wider at the cutting edge than at the shank, the object of this being to prevent any binding on the sides of the keyway. C is a "round nose" chisel, such as is used for cutting off pipes (by chipping a groove round the pipe), fiat plates by cutting a groove across them on either side), or for cutting oil channels in brasses. In order to make the tool more suitable for the latter purpose, the lower part of the shank is often made curved. The production of a more accurate surface than that left by filing is secured by scraping; this operation does not present so many difficulties as chipping and filing, although it requires an equal amount of care and judgment. The scrapers are usually made from old files, and of the form shown in Fig. ;3, where A is a flat scraper, such as is used for scraping flat surfaces. This pattern of scraper is ground up smooth on both sides and on the ends, and square on the bottom it is finished off on an oilstone, and is held at an angle of about 45 degrees to the work ; B is a "half round" scraper, and is used for scraping the bores of brasses ; it is sometimes slightly bent, so that the cutting can be localised. This scraper is held parallel to the line of the bore of the brass and a sweeping movement, lowing the radius of the brass, is given to it. C shows a scraper made out of a three-corner or " saw " file which has been ground smooth ; the edges are sharp, and it forms a very useful scraper for small bearings. In the case of flat surfaces, e.g., slide valves, a surface plate is necessary, in order to check the accuracy of the surface which is being scraped. The surface plate is smeared over with a thin film of red lead and oil, and the scraped surface is laid thereon and given a slight sliding movement ; any high places thus become marked with the red lead and they can then be scraped away. The operation is repeated until the valve is dead-!evel all over. When scraping up brasses, the shaft should be smeared over with red lead and oil ; then the brasses should be laid on the shaft and rocked to and fro, and the high places will be indicated by the transference ot the red lead and oil to the brass. These high 'places should then be eased with a " half-round " scraper, until the brass bears equally all over,
By taking every opportunity of watching an experienced man using the various tools mentioned above, carefully following the few instructions which I have endeavoured to convey, and following these up by a little practice on odd pieces of scrap metal, there is no reason why any intelligent driver should not make a very satisfactory job of any necessary repair to the wagon under his charge. I would, however, add a word of warning to the inexperienced driver: don't dismantle your wagon simply to air your knowledge of its mechanical details.