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.

Folder in use.

Easy to make folder.

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