Furniture manufacturing process

A basic preliminary in all furniture production is the provision of working drawings. In a firm of any size there is invariably a special department where full-size drawings are prepared from small-scale drawings provided by the designer. In some cases the designer may make his own full-size, detailed drawings; but in a large firm it is more usual for a draftsman to work out the practical details, though usually in consultation with the designer, who advises on proportions and decorative details. The hand craftsman, in contrast, usually does the whole thing himself. In the small-scale drawing the general form and essential requirements are worked out; the full-size drawing shows proportions and constructional details. A sample piece is made to check the design and cutting problems. Cutting lists are prepared; the cost of materials, fittings, finish, etc. figured; and an estimate of machining and assembly time worked out. When the work is to be produced in quantity, costs are lowered considerably because only one setting of the machine and only one set of cutters are needed for the whole run of any particular part.

Selection of timber, already passed through the seasoning kiln and converted to standard thicknesses, follows. The wood passes to the machine shop, where it is sawed to size, planed, molded, grooved, or rebated as required. When a number of parts must be cut exactly alike, they are clamped in forms having the proper contour and are then brought in contact with high-speed rotating knives that shape the part to proper size as the form rides against a guide on hand or automatic shapers and routers. Intricately carved pieces such as legs are roughly carved on multiple-spindle carving machines. These duplicate a master leg by means of a follower point that is guided along the surface of the model and imparts the same motions to as many as 32 high-speed rotating knives as they whittle the leg blanks. After the rough carving, the pieces are machine sanded and finished by a hand carver.

If veneering is required, this is now done. Jointing follows—tenoning, dowelling, dovetailing, etc. Automatic machines often combine several operations. Exposed parts are sanded on edge belt sanders, three-drum travelling-bed sanders, or belt sanders. Rounded parts are sanded on soft pneumatic drums, and carved parts are sanded on a buffer, a machine in which shredded sandpaper is supported by brushes on a revolving wheel.

Finally the work passes to the assembly shop where door frames are put together, drawers glued up, and carcasses assembled. After the glue has set, the parts may be returned to the machine department for machining that could not be performed before assembly, such as sanding the joints and shaping the edges. Then it returns to the assembly department for final assembly. Air-driven clamps are used when the design permits; otherwise the piece is pressed by hand clamps. Unless electronically cured glues are used, clamps must be applied long enough to ensure a good bond. The completed article is cleaned to remove excess glue, inspected, and hand sanded. Finally, staining and spray polishing is done and fittings added.

In individually crafted work there is always a great deal of fitting to be done—doors trimmed and drawers made to run easily without slackness. In mass-production work this problem would be serious. It is almost entirely avoided by making drawers an easy rather than snug fit and by sanding the edges of doors to templet size so that they automatically fit the carcasses, which in their turn are made to standard size.

Chairmaking has been a separate branch of furniture making since the mid-17th century. One of the most intricate branches of woodwork, it involves odd angles, compound shapes, and awkward joints and at the same time calls for maximum strength, chairs being subjected to more strain than most other furniture. There are three main types of chairs: the Windsor chair, made largely from turned parts, with solid wood seat; the framed type of dining chair with either loose or stuff-over seat; and the upholstered chair.

In Britain the Windsor chair belongs traditionally to the High Wycombe District of Buckinghamshire where beech trees abound. Until relatively recent times men worked in huts in the beech woods making turned parts for chairs. They felled the trees, cut the trunks and larger branches into suitable lengths, and split them into pieces of a section large enough to permit chair legs and uprights to be turned and also to provide lighter members for rails, etc. They turned the parts on a primitive pole lathe in which a cord was attached to a treadle, taken around the wood to be turned and up to a springy sapling anchored at the lower end to pegs outside the hut. The power was supplied by treadle, the cord revolving the wood; then as the foot was raised the spring of the sapling lifted the treadle and at the same time turned the work backward. The turning gouge or chisel could be used on the downward stroke of the foot only, but the economy of effort was amazing. A complete leg could be rounded, the curves and beads formed, and the ends brought to the required diameter in a matter of seconds. Of course, working in green timber enabled the turning to be done much more easily and quickly than if the wood were dry.

These bodgers, as they were called, made only the turned parts and delivered them to chairmaking firms for assembling. They had no overhead expenses, no power costs, and the only lighting they needed in winter was an oil lamp or candles. They were long able to compete with powered workshops.

The manufacture of the Windsor chair of Victorian and Edwardian times was a specialized trade. The seat, invariably of elm, was hollowed out (bottomed) with a form of adze, and the holes for the legs were bored with a brace fitted with a spoon bit held at the required angle solely by judgment. The better chairs had a hooped back of yew. Today this hand work has been replaced by boring machines that are fitted with a jig to maintain the correct angle. The hollowing of the seat is machined to an extent, but the depth is only slight, compared with the early hand work. Furthermore, traditional timbers—elm, beech, and yew—are frequently replaced by imported timbers.

The quality of framed chairs of the dining type varies widely, but perhaps the outstanding general feature of modern dining chairs is the wide use of dowelled joints rather than mortise and tenon. In the late 19th century this had already occurred to a large extent, the chairmaker’s kit of tools invariably including a dowel plate with a series of holes through which the craftsman hammered roughly squared pegs to form the dowels. Today machine-made dowels are universal, with a glue-escape slot cut in. Dowelling is a far quicker and consequently cheaper process than mortising and tenoning, especially in shaped work where the curved part frequently must be joined at odd angles.

When a chair has compound curvature it becomes difficult and expensive to make. A chair back may be shaped in both front and side elevation (and often in plan as well). Taste and experience are indispensable in providing a continuous curve that will be aesthetically satisfying from every angle. Over the years, experience has been built up, especially on traditional models following period lines; a chairmaker’s workshop invariably carries bundles of templets in plywood for the various parts of chairs, with the fullness provided (where necessary) for a good line.

Dining chairs may be made in sets of half-dozens or dozens, or more cheaply in batches of 50 or 100, depending upon the capacity of the factory. In some cases parts are standardized and interchangeable in different designs of chairs.

The upholstering of dining chairs is a separate trade, though carried out in the same factory, and may be of the loose seat, stuff-over, or plywood-covered type. Traditional stuffing materials such as horsehair have largely been replaced by foam rubber and synthetics.

In individually crafted work there is always a great deal of fitting to be done—doors trimmed and drawers made to run easily without slackness. In mass-production work this problem would be serious. It is almost entirely avoided by making drawers an easy rather than snug fit and by sanding the edges of doors to templet size so that they automatically fit the carcasses, which in their turn are made to standard size.The manufacture of fully upholstered pieces is often a separate branch, though large manufacturers often make both upholstered and nonupholstered types. It remains to a great extent a handicraft, for the skill of trained and experienced craftsmen is needed in turning out quality pieces. The standard upholstery foundation consists of a system of coiled steel springs resting on a webbing of burlap and tied to the furniture frame, which may be of wood, fibreglass, or plywood. The springs are embedded in a filling material, such as rubberized hair, foam rubber, palm fibre, or Spanish moss; and the spring system is topped by a thick padding of cotton or foam rubber in sheet form. Muslin is frequently employed as an inner covering for this assembly, while a durable upholstery fabric is used as an outer and finishing cover. Loose cushions are filled with special spring units in a bedding of foam rubber or down; the springs are covered with layers of cotton, and the entire assembly is encased in upholstery fabric.

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