It Pays to Examine the Wood
Page 42
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A Qualified Timberman Points Out How to Guard Against False Economy in Body Construction, and Makes Clear the Qualities of
Various Woods
TT is noticeable that those operators having vehicles built to order, whilst paying strict attention to mechanical features will almost always accept a body built of any timber which the maker cares to use. Every buyer, however, has the right to stipulate the woods to be used in construction and to inspect the body before it is painted, when any defects in the woodwork can easily be seen.
Defective timber, or even the wrong kind of timber, may make the vehicle a source of constant expense to its owner, more especially in the case of a commercial vehicle, in which the woodwork gets real wear.
For instance, for the sake of "economy," some makers will use oak and beech, instead of ash, for the framework of the body. Oak contains a large amount of corrosive acid and will soon lessen the strength of any ironwork attached to the wood. To obviate this, some bodybuilders use kiln-dried oak, thus ensuring that the acid has been dried out. That, however, is a dangerous process, as it tends to make the wood brittle and impair its strength, and is only exchanging one defect for another.
Ash Stands Bearing Stress Better Than Oak.
Further, although oak is reputed to be the strongest wood in the world, it will not stand so great a bearing stress as ash. Oak is a rigid wood and has not the " give " so necessary to relieve the stress on the whole vehicle when pulling up sharply with a heavy load. Beech, on the other hand, will not stand the heavy wear and tear or vibration to which most commercial vehicles are subjected.
Bodies built of oak or beech may be a little cheaper, but as all woodworkers know, cheap wood is false economy for the user, and it is not long before trouble commences. English ash, naturally dried, is second to none for framework, because no other wood combines so well the qualities of toughness, resiliency and durability which this particular purpose demands, and it is the most reliable wood of its kind.
If American ash be used for framing it should be most carefully selected, as it greatly varies in quality and, in the main, is inferior to English wood. American ash, as imported into England, seems to be a mixture of many different species of the wood, varying much in nature.
rib Consequently, the yield of wood equal in every respect to English ash is a very small percentage.
Moreover, American ash is dried right out, artificially, before exportation—an American custotri with all hardwoods—and although the practice of kiln-drying has many advantages, most woodworkers still aver that it destroys the " body " of the wood.
• Woods Chiefly in Use.
Many more woods are now used in the construction of commercial bodies than formerly, and to enter into the merits and demerits of them all would fill a book. Among those chiefly used are, in addition to those already mentioned, birch, elm, teak, mahogany of many kinds (some doubtful), iroko, pitch pine, British Columbian pine and, lately, parana pine.
It is regrettable that some merchants lead their customers to believe that parana pine is a British wood, whereas it is a Brazilian timber. However, it is an excellent substitute for yellow deal, being more free from knots.
British Columbian pine is now extensively used for bottom boards in the place of deal. It is just as cheap as deal and, being tough and hard,, will stand more wear. Parana pine is better than B.C. pine for painting, for the grain of the latter will show through paint. If the wood be polished in its natural colour, however, it presents a handsome appearance.
For the floor of any vehicle required to carry wet merchandise English elm should be used. This wood thrives on dampness and will stand heavy wear. It is remarkably cheap, too. The only disadvantage of an elm floor is its weight. A floor of ordinary deal would probably save a weight of about 30 per cent., compared with elm. But on a comparison of strength and durability, when used for that particular work, elm would be the more economical in the long run.
Teak can be used for almost any part of a commercial body. A hard, strong and reliable wood, it is both fire and acid-resistant and needs no paint or protective covering of any kind. Some authorities consider it is even better than English ash for the construction of bodies for use in hot climates, as it seldom shrinks. Like all really good material, it is expensive.
Iroko must not be confused with teak, although. it is sometimes marketed as "African teak." Iroko is a much inferior wood and, in reality, is not related to genuine teak. Although like teak in colour, it has a much coarser grain, and has a tendency to "pick up" when being worked. Nevertheless, it is a useful wood, and as it can be obtained in large dimensions it makes excellent sideboards, which, when the wood is polished in its natural state, present an extremely handsome appearance. It is remarkably cheap.
A Decorative Wood in a Class By Itself.
Mahogany, in its many species, still holds its own as a first-class decorative wood for passenger vehicles. To-day, for panelling, mahogany-faced plywood is more often used than solid mahogany. Plywood is cheaper, of course, and from the bodybuilder's point of view has the advantage that it is not so liable to split.
Plywood faced with Honduras mahogany may be used for the highest class of work. Such panels are well manufactured and take an excellent polish. Needless to say, they are the most expensive, but a skilful polisher can obtain good results with the cheaper grades of mahogany plywood, such as sapele and gaboon.
Remember, plywood can be obtained faced on one side only, with the decorative wood required.
Commercial bodies are often built to order, and the seller should be made to state, in writing, the woods of which the body will be constructed. Should the buyer have no knowledge whatsoever of timber, he should obtain the advice of someone who has, and he will find it to be well worth while, for there are few commodities so easily foisted on the uninitiated as defective timber.