The Advantages of the Modern Coachbuilder (continued...)


Construction: Materials and Methods

Introduction
Materials & Methods
Metals Used
Restoring a Body
Building a Body
Windscreens
Hood Frame
Panelwork
The Advantages...

It is a saving grace from the point of view of originality that very few of the original materials have changed or been bettered, although some of the more obscure or toxic substances are now not available. I am a firm believer that where original materials can be used, they should be used. Any modern advantages should only be used to recreate original features, not replace them.

The materials themselves in coachwork fall into just two main groups - wood and metal, both having changed very little, the only real factor affecting choice today is the unavailability of some elements.

Wood framing and structure is generally accepted as being ash, with beech, oak and mahogany being favoured by some coachbuilders, more especially the latter in the much earlier style of body, particularly where wood was employed, its closeness of grain being particularly suitable for shaping and painting. Sycamore, willow, birch, cedar and hickory will all be found in coachwork, sometimes the considerations of choice being more geographical rather than most suitable.

Given the choice, I would always use ash with a specific gravity of 0.76 and the weight per cubic foot of 40lb - nothing quite matches the strength for weight factor of this most excellent of nature's materials. A mix of two types gives us the most versatility - English ash and American white ash. Traditionally, air seasoned English ash, felled in winter when the sap is not rising, log sawn in 3 inch thickness for the heavier construction and shaped timbers, will vary in colour from white to light brown. Although with shakes and splits, wany edges and the like, you will be lucky to achieve better than 50% wastage. With the width of board you will have to use to achieve some of the shaped timbers, it will mean that the timber for the new body or restoration is probably at least as old as the original body. It wouldn't be the first time that a musket ball deeply embedded in the growth of the tree has wrecked the blades of the power planer!

Alpine Eagle Wood Frame

American white ash, kiln dried in sawn planks 6 - 8 inches wide, 1 - 2 inches thick for the straighter more accurate construction. This wood has no equal - its straightness and conformity of grain being second to none - and is always pure white in colour and excellent for carving scrolls or finely chiselled work. It is always wise to remember not to use a thickness of timber much greater than required; that way the finished piece will remain stable.

Wood glues will always have an element of personal choice about them, but my optimum will always be for a powdered resin glue, with void filling capabilities, freshly mixed as required. Waterproof qualities are essential, as moisture in the atmosphere will destroy glued joints just as a thorough continual wetting.

There is probably no better time to dispel the myth concerning the use of brass screws - it is probably the question I get asked the most - 'Do you use brass screws?'. The answer is quite simply, 'No'. Ash is such a strong hardwood, with the sort of depth and thickness of some of the timbers, a hell of a lot of torque is required to drive these screws home good and tight, especially if they are going to be load bearing. Brass screws would just simply twist in half with the power of driving them home, even with the proper attention to accuracy of drill size and depth of countersink, etc. Choose a good quality (you'd be surprised how the quality of woodscrews can vary) slotted woodscrew, not crosshead or Phillips, with one allowable concession - zinc plated to avoid rust, and always drive them home with a slick of saliva; if you use a dab of grease, it will gradually permeate through the wood and destroy the glued joint.

Interior woodwork is another matter altogether, with a whole list of different timbers, inlays and lacquerwork become available to us. And as this feature of the coachwork is more decorative than functional, a whole new area of craftsmanship and creativity is opened up to the coachbuilder and their body styles giving this feature more artistic inspiration than most. But, alas, this is a subject probably best reserved for a separate article altogether.

Introduction
Materials & Methods
Metals Used
Restoring a Body
Building a Body
Windscreens
Hood Frame
Panelwork
The Advantages...

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