COVER A WALL WITH OPEN SHELVING

If the floor space in your kitchen is hopelessly inadequate, try looking to the walls to solve your storage problems and to make every square centimetre work for you. Standard wall cupboards can be expensive and they tend to waste a great deal of surrounding space. In addition, they are often quite deep so it is difficult to reach goods at the back without standing on a chair or knocking over a stack of plates.

This open system has been designed not only to fit the precise dimensions of the kitchen wall, but also to suit the goods which are to be stored there: shelves of various heights will take most sizes of bottle, jar. tin or packet. Traditional wine racks are cheap and widely available – and they are useful for soft drinks as well as vintage clarets. Seldom used articles are tucked away on the very top shelf. over the window, and those things which need to be covered up are stored conveniently in normal floor-standing cabinets.

If you plan this arrangement from scratch, extend the window sill to the same depth as the shelves. making room for a collection of house plants and herbs; screw hooks under the top shelf so you can fit in more greenery by hanging pots at various levels. There will not be room for curtains here, so those who need privacy should look for a simple cane or roller blind.

Soldered joints are often used around the home for fixing light metal articles and electrical connections; you can make them yourself.

Soldering is an easy and inexpensive method of joining light articles made from steel, copper or brass and securing wires made from these materials. The principle of soldering is to melt an alloy and allow it to flow into a gap between the two pieces to be joined. If it is prepared sufficiently well, a soldered joint will be quite strong: but if the design of the work requires a stronger joint, processes known as hard soldering, silver soldering OR brazing may be employed. These techniques will be covered later in the Course.

The difference between hard soldering and ordinary soldering is in the alloy used and in the amount of heat required to melt it into the joint. A typical job requiring soft soldering techniques is the fusing of electrical terminals: this can be done at a relatively low temperature of between 120 C and 240’C.

TYPES OF SOLDER

Solder is an alloy of tin and lead: some solders also contain a little antimony and the speed at which it solidifies depends upon the concentration of tin in the solder. ‘Tin-rich’ solder has a white/yellow appearance and ‘lead-rich’ solder is dull blue in colour.

A fairly wide range of solders is available, the choice depending on the work to be done. The most suitable solder for electrical, audio and instrument work and for any other work which requires a low melting point and good flow properties, is ‘tin-rich’ solder, composed of 64.5 percent tin and 35.5 percent lead, which melts at 183 C. For general work with a coppersmith’s bit. a solder containing about 45-50 percent tin is most suitable: this has a melting range of 185-215’C.

The high lead content in ‘lead-rich’ solder means the solder becomes plastic in the temperature range of 180-250°C. which allows the joint to be wiped with a thickly folded cloth to give a smooth final finish. A glance at a plumbing joint will provide a good example of such ‘wiped joints’.

Although soft soldering methods are best suited to steel, copper and brass, they can also be used to solder cast iron, aluminium, zinc and stainless steel. But to tin these surfaces properly, you must be very attentive to cleaning and preparation. These metals form oxide skins which are resistant to the solder’s adhesive qualities so they require special fluxes; manufacturers will supply information about the best combinations to use.

FLUX This acts both as a cleaner and as a conductor. helping to transfer heat to the work during the soldering process. However carefully the pieces to be joined have been cleaned by filing or scraping. there is still likely to be a thin, invisible film of oxide on the surface; flux helps to remove this deposit. But remember the use of flux is not an alternative to adequate cleaning and preparation of the surfaces to be joined.

Fluxes are classified as active or passive. The most common active flux is zinc chloride, also known as ‘killed spirit’. This is made by dissolving zinc chips in hydrochloric acid, but it is more easily prepared by buying commercially fused zinc chloride and mixing it to a paste with water. Although it is a very efficient flux, it is also a corrosive one: after using it, the joint must be washed thoroughly in a solution of hot water and washing soda.

When soldering electrical connections and in any situation where it is important to avoid corrosion. passive fluxes should be used. Most passive fluxes are based on resin and can be bought in tins. For light work you can buy rcsin-cored solder which combines flux and solder: it is available in wire form and looks similar to electrical fuse wire.

SOLDERING IRONS

A soldering iron or blowtorch is essential for applying heat to the joint. The simplest consists of a piece of copper fitted to an insulated handle. The end or ‘bit’ is in the shape of a point so it can be used in restricted spaces. The size and weight of the iron will depend upon the type of work you intend to undertake. For example, audio and electrical work require a small bit, while work on sheets of metal needs a larger bit; if the bit is too small it will lose heat too quickly.

ELECTRIC This is probably the most convenient soldering iron for work at home because the copper bit is heated continuously to ensure the alloy melts. Flame-heated This type has to be heated before use and reheated as it cools down during the soldering process. The heat can be applied from a gas ring or, when working out of doors, from a camping gas stove. The need to heat and reheat is a minor disadvantage: but good joints can be made as long as the bit is not allowed to cool down too much.

BLOWTORCH For soldering copper pipe joints or long seams in tin plate, a blowtorch fuelled by butane or propane is very convenient. It is essential to remember, when choosing soldering equipment. that the greater the amount of metal in and surrounding the joint, the greater the heat required.

MAKING THE JOINT

The first step in soft soldering is to ensure the surfaces to be joined and the bit of the soldering iron are clean. The surfaces of the work must be brought back to bright metal with a wire brush, emery cloth or scraper. The bit can be cleaned by gentle filing while heating to a temperature slightly higher than the melting point of the solder being used. Remember the purpose of the soldering iron is to convey heat to the joint; to do this effectively it should always be at least 50°C hotter than the melting point of the solder. This is of particular importance when using a flame-heated iron.

Once the cleaning process is complete, you can coat the bit with solder ; dip the bit into the solder, making sure all its sides are coated. Tinning the bit is easiest when using resin-cored solder which deposits flux and solder at the same time. Otherwise use two tin lids – one to hold the flux, the other to hold small pieces of solder.

When the bit has been tinned, apply one of its flat sides to each of the joint surfaces in turn, so they too are tinned. Carefully position the two pieces to be joined, bring the surfaces together and hold them with a clamp or some soft wire. Apply the bit to the outside of the joint and run solder into the joint; it will melt on contact with the heated surface.

WARNING

A large amount of heat will be lost down the sides of a metal vice or clamp if either of these is used to hold the work. It is best to work on a timber surface and hold the work between timber packing inside the vice. The only exception is when soldering transistor components; these may be damaged by excess heat travelling along the wires, so it is necessary to provide a ‘heat sink’. This is easily done by gripping a pair of pliers onto the bare wire between the joint and the delicate transistor; the pliers will absorb some of the heat.

Ensuring strong joints

A good joint begins at the design stage; if possible the joint should be designed so any load is taken by the basic material and not by the solder. It is also important to allow sufficient space between the surfaces of the joint so the solder can flow easily; the joint should then be quite strong but must be free of excess solder. You should practice with pieces of scrap metal before attempting the main job. If the iron is kept hot and the bit is properly tinned, you will find it relatively easy to make good joints.

All soldered joints lose some strength at high temperatures and it may be better to consider some other fastening method if your finished workpiece is likely to be subjected to such temperatures.

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