Page:EB1911 - Volume 15.djvu/505

Rh are used in the best work, and, carefully worked and glued, with the assistance of angle blocks glued at the back, obviate the necessity of face screws or nails. The keyed mitre consists of a simple mitre joint, which after being glued up has a number of pairs of saw cuts made across the angle, into which are fitted and glued thin triangular slips of hard wood, or as an alternative, pieces of brass or other metal. Other forms of angle joints are based on the rebate with a bead worked on in such a position as to hide any bad effects caused by the joint opening by shrinkage. They may be secured either by nailing or screwing, or by glued angle blocks.

The dovetail is a most important joint; its most usual forms are illustrated in fig. 3. The mitre dovetail is used in the best work. It will be seen that the dovetail is a tenon, shaped as a wedge, and it is this distinguishing feature which gives it great strength irrespective of glue or screws. It is invaluable in framing together joiners’ fittings; its use in drawers especially provides a good example of its purpose and structure.

Warping in Wide Boards.—It is necessary to prevent the tendency to warp, twist and split, which boards of great width, or several boards glued together edge to edge, naturally possess. On the other hand, swelling and shrinking due to changes in the humidity of the atmosphere must not be checked, or the result will be disastrous. To effect this end various simple devices are available. The direction of the annular rings in alternate boards may be reversed, and when the boards have been carefully jointed with tongues or dowels and glued up, a hard-wood tapering key, dovetail in section, may be let into a wide dovetail at the back (fig. 4). It must be accurately fitted and driven tightly home, but, of course, not glued. Battens of hard wood may be used for the same purpose, fixed either with hard-wood buttons or by means of brass slots and screws, the slots allowing for any slight movement that may take place. With boards of a substantial thickness light iron rods may be used, holes being bored through the thickness of the boards and rods passed through; the edges are then glued up. This method is very effective and neat in appearance, and is specially suitable when a smooth surface is desired on both sides of the work.

Mouldings are used in joinery to relieve plain surfaces by the contrasts of light and shade formed by their members, and to ornament or accentuate those particular portions which the designer may wish to bring into prominence. Great skill and discrimination are required in designing and applying mouldings, but that matter falls to the qualified designer and is perhaps outside the province of the practical workman, whose work is to carry out in an accurate and finished manner the ideas of the draughtsman. The character of a moulding is greatly affected by the nature and appearance of the wood in which it is worked. A section suitable for a hard regularly grained wood, such as mahogany, would probably look insignificant if worked in a softer wood with pronounced markings. Mouldings worked on woods of the former type may consist of small and delicate members; woods of the latter class require bold treatment.

The mouldings of joinery, as well as of all other moulded work used in connexion with a building, are usually worked in accordance with full-sized detail drawings prepared by the architect, and are designed by him to conform with the style and class of building. There are, however, a number of moulded forms in common use which have particular names; sections are shown of many of these in fig. 5. Most of them occur in the classic architecture of both Greeks and Romans. A striking distinction, however, existed in the mouldings of these two peoples; the curves of the Greek mouldings were either derived from conic sections or drawn in freehand, while in typical Roman work the curved components were segments of a circle. Numerous examples of the use of these forms occur in ordinary joinery work, and may be recognized on reference to the illustrations, which will be easily understood without further description.

Mouldings may be either stuck or planted on. A stuck moulding is worked directly on to the framing it is used to ornament; a planted moulding is separately worked and fixed in position with nails or screws. Beads and other small mouldings should always be stuck; larger ones are usually planted on. In the case of mouldings planted on panelled work, the nails should be driven through the moulding into the style or rail of the framing, and on no account into the panel. By adopting the former method the panel is free to shrink—as it undoubtedly will do—without altering the good appearance of the work, but should the moulding be fixed to the panel it will, when the latter shrinks, be pulled out of place, leaving an unsightly gap between it and the framing.

Flooring.—When the bricklayer, mason and carpenter have prepared the carcase of a building for the joiner, one of the first operations is that of laying the floor boards. They should have been stacked under cover on the site for some considerable time, in order to be thoroughly well seasoned when the time to use them arrives. The work of laying should take place in warm dry weather. The joints of flooring laid in winter time or during wet weather are sure to open in the following summer, however tightly they may be cramped up during the process of laying. An additional expense will then be incurred by the necessity of filling in the opened joints with wood slips glued and driven into place. Boards of narrow width are better and more expensive than wide ones. They may be of various woods, the kinds generally preferred, on account of their low comparative cost and ease of working, being yellow deal and white deal. White deal or spruce is an inferior wood, but is frequently used with good results for the floors of less important apartments. A better floor is obtained with yellow deal, which, when of good quality and well seasoned, is lasting and wears well. For floors where a fine appearance is desired, or which will be subjected to heavy wear, some harder and tougher material, such as pitch pine, oak, ash, maple or teak, should be laid. These woods are capable of taking a fine polish and, finished in this way, form a beautiful as well as a durable floor.

Many of the side joints illustrated in fig. 1 are applied to flooring boards, which, however, are not usually glued up. The heart side of the board should be placed downwards so that in drying the tendency will be for the edges to press more tightly to the joists instead of curling upwards. The square joint should be used only on ground floors; if it is used for the upper rooms, dust and water will drop through the crevices and damage the ceiling beneath. Dowelled joints are open to the same objection. One of the best and most economical methods is the ploughed and tongued joint. The tongue may be of hard wood or iron, preferably the latter, which is stronger and occupies very narrow grooves. The tongue should be placed as near the bottom of the board as is practicable, leaving as much wearing material as possible. Two varieties of secret joints are shown in fig. 1.—the splayed, rebated, grooved and tongued, and the rebated, grooved and tongued. Owing to the waste of material in forming these joints and the extra labour involved in laying the boards, they are costly and are only used when it is required that no heads of nails or screws should appear on the surface. The heading joints of flooring are often specified to be splayed or bevelled, but it is far better to rebate them.

Wood block floors are much used, and are exceedingly solid. The blocks are laid directly on a smoothed concrete bed or floor in a damp-proof mastic having bitumen as its base; this fulfils the double purpose of preventing the wood from rotting, and securing the blocks in their places. To check any inclination to warp and rise, however, the edges of the blocks in the better class of floors are connected by dowels of wood or metal, or by a tongued joint. The blocks may be from 1 to 3 in. thick, and are usually 9 or 12 in. long by 3 in. wide.

Parquet floors are made of hard woods of various kinds, laid in patterns on a deal sub-floor, and may be of any thickness from to