GEOFFZONE
Our vehicles are made mainly of steel, with some aluminium, copper, brass, glass and plastics. Metals are ‘ferrous’ or ‘nonferrous’. Ferro means iron, the base material being iron ore. Any grade of steel is ‘ferrous’, including stainless. Steels are usually the hardest, strongest and toughest metals we find in vehicles. Non-ferrous means ‘not containing iron’. All other metals fit this category – aluminium, brass, copper, lead etc. and alloys made from a mixture of them. More exotic metals such as titanium are rarely used in consumer vehicles. Some steels may be hardened to varying degrees and are used for knives, gears, bearings, tools, etc. There are many types of steel, with their uses and characteristics defined by other minerals added during manufacture. All steels contain some carbon, for instance, the percentage – between 0.02 percent and two percent carbon – dictates intended usage. Structural or ‘mild’ steel is low carbon and by far the most common and easiest to work with. High carbon is used for tool steels. If you needed a piece of steel for a project it would most likely be mild steel in sheet or bar form. Best place to get it? Sheet steel – get offcuts or cut to size from a sheetmetal workshop or panelbeater. Beware sharp edges! Bar, as in round or hexagon section – you get from a machining workshop. Flat, square, angle, box (hollow) sections – from any general or structural engineering workshop. Depends on quantity, but a good rule of thumb is small amounts and offcuts as above, large amounts from steel suppliers. Most long types come in five or six metre lengths, which is quite long to carry and may be heavy. I used to transport six-metre lengths down the side of a LWB ‘Cruiser, supported by a pivoted hook on the bushbar and a sling at the rear. Not sure how legal it was, but it worked! Non-ferrous metals are seldom available from steel suppliers. Often you can get a wide range from one outlet although some deal with only aluminium alloys and extrusions. Extrusions are round or square tubes or angles or more complex shapes like those used for window and door frames, many of which are proprietary so only available from their branches. As with steels these materials are alloyed for different uses. Some are soft for easy bending or forming but may be too soft for other uses. For machining some may be got as a ‘free-cutting’ type that is easier to work. Hard varieties will be stronger and stiffer but will crack if bent too tightly. Some are stamped or polished for decorative appeal. Sheet material is sold in fixed sizes, the most common being 1.2m x 2.4m though some have larger options. A sheetmetal workshop will usually cut sheet to size and may also fold if required. Many will be able to punch accurate holes or patterns to a design. Bar stock suppliers will usually have cutting facilities but often will not cut smaller sections or may have a minimum length limit – meaning that if you want 800mm of 6mm round bar you may have to buy the whole bar. Most will halve a full length for easier transport. Many cars, SUVs and 4WDs will fit a 2.4 length between the front seats but few will take 3m without a door or window open. Careful with that! Steel often has scale or an oily coating so take rags to protect upholstery and clothes and to clean hands. Leather gloves can be handy. Most metals may be joined by welding, brazing or soldering, but require the equipment and expertise to do it. Lacking these? Then get an appropriate engineer to do it. Ferrous and ‘non-F’ require different equipment and techniques for welding. Joining with bolts, screws or rivets can be achieved with hand tools and drills (use eye protection!). Steels and aluminium alloys are denoted by code numbers that reveal their composition and characteristics. It’s not necessary for nontechnical persons to know these, suppliers should be able to recommend appropriate product. Should you be getting something made by an engineer be aware they expect to work from drawings or sketches dimensioned to millimetres There’s an easy-to-make sheet folder – a piece of angleiron has a central section of one flange removed then the remaining flange bent around a former so it can flex (or three trimmed hinges welded together would work). It is clamped across the sheet then the fold is tapped with a hammer.