REPAIRS on the road must necessarily be carried out as and when occasion demands—the average breakdown is no respecter of time or convenience, and action must be taken on the spot irrespective of conditions. But first we are concerned with the repairs that can be undertaken at leisure in the home garage.
Adjustments to engine, transmission, brakes and the all-important periodical greasing, oiling and de-carbonizing are all processes that can be performed best under the sheltering roof of the garage.
The question of adjustments and repairs should always be considered in the initial choice of the garage itself. Whether the building be of timber, asbestos, brick or sheet iron, it should always be provided with a concrete floor, and in this connection an inspection pit is an item not to be despised.
The overall dimensions of the garage should, wherever possible, exceed the car width by 3 ft. or 4 ft. and additional length to the maximum permitted by the extent of the building site will provide space for the all-important workbench.
Many car owners prefer to have the bench at the far (or engine) end of the garage under a wide window.
To anyone able to handle carpenter’s tools the construction of a bench will be easy. Strength and rigidity are the two features at which to aim; therefore, the bench legs should be of 3-in, square timber, whilst the top boards may well be 1 ins. To 2 ins. Thick. An alternative scheme is to use a thick front board with thinner planks, say, 1-in., making up the width.
The actual design of the bench will depend upon the individual. It must, however, be securely fastened to the wall and floor of the garage. Regarding the dimensions, a length of 6 ft. and a width equal to three “9-in.” boards will be found useful; there is, in fact, no particular point in exceeding this size unless a bench lathe is to be accommodated.
A very important point is the height of the bench. For the sake of giving a definite dimension, 2 ft. 9 ins. May be suggested; actually, however, it is governed by the working height of the vice which will be bolted to it, the rule being that the elbow, when standing with the hand supporting the chin, should just rest on the vice jaws. Some care should be taken to secure the correct height because, in addition to the personal discomfort entailed, using a vic6 which is ‘too high or too low makes accurate work, especially filing, a matter of difficulty.
It is false economy to buy a cheap vice. A very suitable type for amateur use is one of the parallel variety with jaws not less than 4 ins. Wide. The jaws should be of steel and detachable, whilst if the screw is of the quick-release type so much the better. Some vices are obtainable with pipe-grip attachments and swivelling bases—two features which will be found extremely handy at times.
The vice should be rigidly bolted to the bench, near one of the legs if possible. Square-headed coach screws form a convenient method of fixing, or the bench top may be drilled and the vice secured with bolts and nuts, large-diameter steel washers being used to back up the nuts. In any case never try to fix a vice with wood-screws or nails—they will not hold it.
Having erected the bench and vice—it is assumed, by the way, that a well-lighted position has been chosen—there remains the question of tools and equipment. No hard and fast rules can be laid down because so much depends upon the mechanical knowledge of the individual and the amount of money he is prepared to spend. It is much better to buy various tools and pieces of equipment as required rather than to spend good money without due consideration as to the ultimate usefulness of the pieces purchased.
There are, however, certain tools which must be available. These include files, hammers, a hacksaw, drill brace, drills, punches, cold chisels, and so on. More elaborate tools, such as screwing tackle, a bench drill, emery grinder, or even a lathe, can be added from time to time as the need arises or as experience is gained. Every tool, no matter how humble its type, should be chosen with due care, and a few words of advice will prove useful to those who are paying their first visit to the toolshop., Files
A good selection of files is necessary. For work where there is plenty of metal to be removed the amateur should obtain those known as Dreadnought, preferably 12 ins. A 10-in, flat rough file with one safe edge (an edge without teeth) and a “ second cut” file of similar size will also be founil useful, the latter especially for brass, gunmetal or cast iron. Finishing cuts may be given with an 8-in, flat smooth file, but except for instrument work there is no point in buying dead smooth files.
Half-round, second-cut and smooth files in 8-in. And 6-in, sizes are worth having, together with a few round and square types, both rough and smooth. Warding, needle or other special files may be bought when they are needed.
If the amateur starts with a dozen files as indicated he will be well equipped for all ordinary work.
It is most important to fit the correct size of handle to each file and to see that it is secure. A handle that is badly fitted may result in the tang of the file releasing itself on a forward stroke and penetrating the palm of the hand. Do not adopt the practice of making, say, three handles serve for six files. The handle should always be looked upon as a part of the file, as in the case of a wood chisel. Buy the plain beechwood, steel-ferruled handles; patent types and those covered with yellow varnish are not for the practical man.
A hacksaw of the adjustable type with pistol grip will be found the most convenient, this form of grip giving better control and greater comfort in use than the straight-handle type which is more suitable for light work.
With regard to blades, whilst these are put 7up in dozens, they can, if necessary, be purchased singly. Three of each variety—coarse, medium and fine—should, at any rate, be sufficient for a start. Inexperienced workers will probably have many broken blades, and there are two main reasons for this; one is the failure to use the whole of the blade at each stroke, and the other using the wrong type of blade for the work on hand. Unless a full stroke be given to the saw each time, only the centre portion becomes worn, and when a full stroke is made the unworn teeth on the ends jam in a slot which is too narrow for them. Most saw breakages occur when cutting thin tubing. Naturally, if the teeth are coarse, a tooth will lock in the thin metal, and a vigorous forward push will immediately cause the saw to break its teeth or snap.
Hammers, Chisels and Punches.
At least three hammers should be provided, and they may be of the ball-pene type; the respective weights may be 4 lb., 1i-2 lb., and a small fellow suitable for such jobs as riveting.
A good-quality hammer differs from a cheap one in feeling nicely balanced, similar, in fact, to the difference between the handling of a first-class tennis racket and a cheap one.
Cold chisels for cutting thick sheet metal will be required. They are not expensive, but it is important that they be properly tempered, otherwise the edge will either turn over or chip. Convenient sizes for two chisels would be 1- in. and 1 in. respectively. Other useful types of cold chisel are the cross-cut and the round nose. Each has its uses, which will be explained later.
Coarse and fine centre punches must be available, together with pin punches. A fine centre punch—or dot punch, as it is often called—is needed for marking out work preparatory to drilling or when filing to a line, whilst a coarse centre punch may be used for making a good “ dent “ to form a guide for a drill point. Pin punches are used, of course, for driving out taper pins and for similar work.
The need for drilling holes arises frequently in repair work, but, in most cases, a Fin, hole is the largest that is required. Unfortunately, however, a drill brace capable of taking a fin. Drill is a rather heavy and cumbersome tool; furthermore, a hole of this size requires strength to drill by hand. A hand drill having two gears will, however, greatly reduce the effort required. It is a good plan to buy a small brace with a chuck taking up to 1 in., and either another hand brace with two gears to take larger drills, or, what is more practicable, a strong
bench drill with which fin, holes can be drilled without undue effort. These are by no means expensive and, of course, permit of far greater accuracy being obtained than is possible with any brace held in the hand. It may be necessary also to purchase a machine vice, as it is somewhat difficult to prevent work from revolving as both hands are necessary to operate the drill, unless one of the self-feeding type be purchased.
Portable Electric Drills.
Apart from the convenience of being able to drill holes “on •the job,” and with a minimum of effort, a portable electric drill can be adapted for use as a grinder, whilst with a suitable flexible drive, emery or carborundum wheels of special conformation can be used for such purpose as the cleaning up of portways and passages, which are frequently left with varions obstructions in the way of fins and bumps.
Such drills, complete with attachments, can be obtained for from £2 upwards, but the amateur is warned against buying any piece of equipment of this nature from any but an established concern.
Size and Types of Drills
There should be a good selection of twist drills in sizes ranging from /Lc in. upwards.
Sized drills usually go up in 1/84 in., so that when threads of small diameter are being cut the tapping holes should be made with a numbered drill; these range from No. 0, the largest, up to No. 60, or even smaller, but if holes not less than 1 in. Whitworth are being tapped there is no need to go smaller than No. 39, which is the correct size tapping drill for that thread. There is no advantage in trying to obtain a tight thread by using a smaller drill than the correct one; rather is it probable that the tap will break off owing to its inability to clear itself.
A table giving the correct drill sizes for various sizes of taps is set out in the appendix.
In most cases it will be found that twist drills are the most suitable tools with which to make holes. Certain metals, notably aluminium, can, however, more easily be drilled with flat drills; this type of drill also has advantages when working on thin sheet metal in which twist drills are apt to “ pick up” when breaking through. Flat drills can easily be made at home.
The tools which have already been mentioned will form a useful nucleus and will enable many ordinary jobs to be done, but the workshop cannot yet be regarded as fully equipped.
Soldering and Brazing,Equipment
Soldering or brazing work may have to be undertaken, therefore the necessary appliances must be on hand. In both classes of metal-jointing a source of heat is needed and, if gas is laid on in the workshop, a blowpipe either of the self-blowing or bellows type will be found most handy; in addition, a bunsen burner can be fitted up for heating the soldering iron and for sweating. Failing a supply of gas, a good pressure-type paraffin blowlamp should be obtained; this will give a flame hot enough for brazing and light forging and, of course, will also heat a soldering iron.
The Electric Soldering Iron
An alternative so far as soldering is concerned is an electric iron—provided that the current is available. These irons are made in various sizes and, for motor work, care should be taken not to buy one of the small type intended mainly for wireless constructors; they have an insufficient heating capacity for use on large work. In this connection it may be mentioned, with regard to ordinary soldering irons, that one with a l2-oz. “ bit “ and one weighing, say, half that amount, will be found very useful.
A necessary adjunct to the blowpipe or lamp is a brazing hearth. Convenient pedestal types lined with firebrick and having clips to hold the blowlamp can be bought, but a stout sheet-iron tray packed with charcoal, used coke or broken firebrick will prove quite a good substitute and cost next to nothing.
A set of stocks and dies for cutting threads is almost certain to be required and, for general work, the Whitworth pitch can be used. The majority of the threads on British cars, however, are of the B.S.F. (British Standard Fine) thread which is not so coarse as the Whitworth pitch. The metric pitch is used on Continental cars and, except in the case of certain electrical fittings on cars, no use is made of the B.A. (British Association) thread familiar to all wireless constructors.
It must be stressed that one pitch of thread cannot be used in conjunction with another. Thus a fin. B.S.F. Nut will klot screw on to a fin. Whitworth bolt, as the fin. B.S.F. Pitch
is 26 threads to the inch, whilst there are 20 threads to the inch in the fin. Whitworth pitch.
Useful Sizes of Stocks and Dies
The choice of screwing tackle therefore must be given due consideration, especially as the sets are rather expensive and it may not be practicable therefore to possess both Whitworth and B.S.F., for example. A useful set in either pitch would consist of dies cutting h-in., h-in. And fin. Threads and corresponding taps, with, of course, the appropriate stocks and tap wrenches. Adjustable, can easily be started truly on the rod; they are, however, rather more expensive than the round type.
As a rule there are three taps for each size, known as taper, second and plug. The taper tap is used first, as it will enter the hole readily, but it does not cut a full thread; therefore the “second” tap is passed through the hole, cutting the thread to the correct size. Except for tapping fully to the bottom of blind holes—that is, holes which do not go right through the work—the plug tap is of little use and, because of this, many sets of screwing tackle do not contain plug taps.
Types of Dies
There are two kinds of die, circular and two-piece. The circular type is very popular, but it has the disadvantage of being a little difficult to use on full-diameter rod, the tendency being to cut the thread eccentric with the axis of the rod unless the threads be cut in the lathe with a die holder held in the tailstock.