MARCH, 1931 FOR THE AMATEUR
The Owner’s Worksho
1 * Nthe last article of this series there was a hint that it was time I considered the matter of working on
• engines, which many amateurs are apt to consider as being the only part of the car that needs any attention. Before -coming to this subject however, there are still many other sorts of work to be considered, a few of which are well within the -scope of the ordinary owner, and which, moreover, will save him quite a lot of money in the course of a season if he does them himself, thereby leaving some cash for the things which definitely come outside his province. The number of people who think they are good at soldering is regrettably in excess of the number who are really able to do this successfully and neatly, so we make no apology for reverting to this
• somewhat prosaic subject, in an endeavour to smooth the path of the amateur in this particular direction. The rules for sol-tiering are few and simple, but they must be followed. The two chief ones are firstly to get the work (and the iron, if used) absolutely clean, and secondly to use sufficient heat.
.Simple Equipment. Many of the jobs which come in the amateur’s way, are to do with broken petrol and oil pipes and unions, which are more annoying than interesting. It is, however, on little things of this sort that the reliability of car, both in competitions -and ordinary work chiefly depends, and .a little care in this department will be amply repaid. The first essential is of .course some suitable source of heat, and if gas is laid on to the garage this is a very simple matter, as there is a great variety of blowlatnps and burners suitable for use with the ordinary supply. A ring will do well for heating irons, while one of the larger blowlamps with foot* -operated bellows is very useful if more ambitious work in the way of brazing or small forge work is intended. A small
forge can easily be made up with a sheet of iron as a tray with some clinker in it, supported on a simple angle iron frame.
Small forges can be bought ready-made of course, but as the use to which it is likely to be put is very small, it is usually sufficient to improvise something as and when required, to avoid room being occupied by gadgets which are not often needed. I have found that a few bricks on a sheet of metal makes an excellent brazing hearth. However, brazing is another matter and before considering it we had better return to the matter of soldering and the heating required for the same.
The majority of owners will not have gas laid on to their workshop so they will need to resort to a paraffin or petrol blowlamp. Personally I would not be without a small blowlamp of this type however much gas was available, as there is nothing so convenient for small soldering jobs where it is necessary to heat up the work itself. In many cases this is a far easier way than using an iron, especially for pipe work. The pipe can be cleaned, heated, dipped in flux and “tinned,” by applying the solder direct. The same method can be applied to many parts, and is a quicker method than using the iron. Once tinned they can be reheated and joined. It is a great mistake to try and make one size of blowlamp compromise for all sorts of jobs. If brazing is to be under
taken a really large blowlamp is essential, and though it will cost £3 to 24, there is very little work in connection with the straightening out of a motor car which cannot be managed with it. I have straightened quite a heavy front axle by means of a paraffin blowlamp, using a few bricks by way of a forge, while any brazing job can be tackled with a large lamp.
For soldering a small lamp that is not going to be too heavy on the wrist is a sound plan for such work where a lamp is desired. It must not be thought from the previous remarks that a lamp will suit every soldering job, and an iron must be used in many cases. For work such as tank repairs or similar sheet work an iron is essential. Instruction in the use of an iron can be of little use compared with actual practice, while in these days the spread of the amateur wireless fiend has made the elements of soldering practice much more generally known than was the case a few years ago.
The fastening of wires to terminals is, of course, rather inadequate training for the various kinds of soldering needed on a motor car, but it is at least a start. In the more varied field, however, there are various snags which make neat work difficult. The chief of these is the fact that to make a neat seam on a tank or similar article, it is essential to have an iron which will retain its heat and so keep the solder flowing evenly. This means a large and heavy iron which is tiring to use on a long job, and also difficult to get into difficult corners. A light iron is pleasant to work with, but as it only retains its heat for a very short while it is comparatively useless. A thing to remember about soldering, which is often lost sight of, is that it is not merely a matter of heating up and melting the solder itself. To make a join between, say, two sheets of tinplate, it is
necessary to heat up the sheet itself to such a temperature that it will in turn keep the solder flowing on its surface until it has penetrated the seam. Then when it cools down a firm joint will result. In this case the heating has got to be done by the iron, and it will be readily seen how a small iron will rapidly loose all its heat to the far greater bulk of metal with which it is in contact.
Fortunately the ideal of a light iron which remains hot indefinitely is not so impossible as it may sound at first. The solution lies in the electric soldering iron. This resembles the standard article in appearance and carries the heating element just behind the copper bit. It is surprising that more of these useful instruments are not in constant use, as they are amazingly convenient, use very little current, and cost only 10s. to 15s. There seems to be an idea that they are delicate or unreliable, but one
or one which I have had for some three years is still as good as ever. It has been used by all and sundry, and no care has ever been taken of it, but it does not appear to object. For soldering a long seam in a tank it is ideal, as the job can be carried through from start to finish without a stop.
Ideas vary in the flux to be used, but I prefer Baker’s Solution to any other kind. For some special electrical jobs one is told to use special non-corrosive fluxes, but in motor car work there is nothing generally to worry about except making a firm joint, and the above mentioned fluid functions excellently.
Brazing is simple.
Brazing is often regarded as a rather mysterious process which is quite outside practical politics for the amateur. Actually, given a suitable source of heat, such as a real he-man blowlamp, brazing is almost easier than soldering, and for parts such as exhaust pipe and silencer stays, extra headlamp brackets, etc., is far the best way of fixing them. The “process is similar in principle to soldering in that it involves the use of a joining medium with a low melting point in comparison with the metals to be joined, and employs a flux to prevent the cleaned surfaces from oxidising before the metal has started to flow. The process is chiefly suitable for, though not confined to, iron and steel. As the name suggests, the joining medium consists of brass, usually in the form of a heavy wire, or else as a powder, when it is known as spelter. Probably the most extensive use of brazing is in the cycle trade and it is ideal for this class of work. There are many cases on a motor car where tubing and lugs can be used and made a wonderfully strong and very
neat job. These can be obtained from Chater-Lea and similar concerns in a huge variety of sizes, and make a far better looking job than the crude affairs of strip and angle iron which so often spoil an otherwise decent vehicle.
The flux used is borax powder or one of the compounds sold for the purpose. The method of making a simple joint between two tubes by means of a T lug is roughly as follows.
The ends of the tube and the inside of the lug must be thoroughly cleaned with emery and then the parts fitted together with as much borax inside the joint as can be managed. On small size work where it will be difficult to get the brass to flow in easily, the joints should also be packed with spelter to ensure the join covering the whole surface.
In many cases it is advisable to pin the joint before brazing to stop it shifting while being joined. The mistake so often made is to imagine that the pin has some connection with the strength of the joint. A well brazed joint should not depend on the pin, any more than the drive on a taper should depend on the key. The essential point in both cases is that the join should be between the surfaces only. In one case this is due to friction, while in the Case of brazing it is by the rather peculiar fusion between the metals, the exact theory of which is somewhat outside the -scope of these remarks. For this reason I prefer to dispense with pinning the joint in any cases where the parts can be held in some other way until completed. There is then no danger of weakening the parts by drilling, and if it is required to take them apart again, this can be done by merely heating them.
Having got the work ready it should be propped up with a few bricks packed round behind it to retain the heat and heat applied with the blowlamp till the joint is a bright red heat. The brazing wire can then be applied to the top of the joint and when a sufficient temperature is reached the brass will flow like water into the joint. When it flows right through, the lamp can be removed and the work allowed to cool in the improvised forge. The heat required for brazing is considerable, being well above red heat, but it is bad practice to get it hotter than necessary as it tends to burn the metal. It also renders the joint brittle if it is cooled too quickly so that it is advisable to let it drop to a black heat before removing from the hearth. As well as the numerous structures possible with tube, brazing can be used for various clips made from strip steel, such as pipe clips, etc., where it is more
permanent and reliable than a nut and bolt.
The joint will be found to be covered with a hard scale caused by the melted flux and should be cleaned up with a stiff wire brush while still hot, as this will simplify the final cleaning up with a coarse file.
\lien any petrol or oil pipe is removed for repair it is a good thing to anneal these to avoid possible fracture due to vibration. The pipe should be heated to a dull red and plunged into cold water. Although this has a hardening effect on steel, its effect on copper is to make it soft and easily bent. It will be found that the vibration of use will gradually harden the pipes again, so the annealing should be repeated every few thousand miles.
Both soldering and brazing are simple processes in which a little practice will enormously improve the neatness of the work, and enable many jobs to be done which would have had to be done by a garage, or else left undone altogether.
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