The Technique of FURNITURE MAKING

Hinges and hinging

Rapid assembly of furniture components in production-work calls for face-fixing hinges, or hinges which can be sunk in circular recesses, drilled or routered out instead of a hand-cut oblong recess; and many new types have been developed with this in view. These new hinges do not, however, supersede the traditional types but complement them, and for the hand­worker the familiar types of square or oblong, cast or extruded brass hinges remain viable.

BUTT HINGES

Steel hinges are used in joinery and brass in furniture. The standard brass butt is shown in 255:1, with 255:1 A the section of the solid drawn type, and 255:lB the cheaper pressed or folded pattern. Plastic hinges are also available, suitable for light work. The width across the plates (leaves or flaps) is governed by the overall length, which is the listed size, and four ranges are usually available—narrow suite, broad suite, strong suite and extra-wide broad suite, with lengths rising in 1/4 in (6 mm) for 1 in (24 mm) to 2 in (50 mm) long, and in 1/2 in (12 mm) increases after. Variations of this type of hinge are: lift-off butt (255:4) for doors which have to be removed from time to time without disturbing the setting; strap hinge (255:3) for narrow sections; loose pin hinge also known as ball-tipped hinge (255:5), where it is required to throw the door clear of the carcass frame with the whole of the hinge knuckle protruding. Figure 255:6 is the stopped hinge opening through 90° only for box lids, etc.; 255:2 is the back flap hinge with wide plates for table leaves and rebated or rabbeted fall flaps; 255:8 is the clock case hinge with one plate wider to allow for a projecting door (255:17), and 255:7 the piano hinge in continuous strip form for supporting long lengths, supplied in either drilled and countersunk or undrilled blanks. Figure 256:1 is the rule joint or table hinge with an extra wide plate to clear the hollow in a moulded rule joint, and with the knuckle on the reverse side to allow a full 90° drop (256:2).

HINGING BUTTS

So long as the hinges amply support the door or flap, the actual positions are not critical, although appearance must be studied and reference should be made to Door construction, Chapter 23. The plates can be recessed equally (255:9), or the total thickness of the hinge cut into either the door or the carcass (255:10), for it is the position of the knuckle which governs the throw of the hinge. If cut in as 255:9 a well - fitted door flush with the carcass edge might tend to bind on the corners, while with an inset door the knuckle would cut across the projection; therefore on balance the method shown in 255:10 is usually adopted, as this gives a neat finish and allows the stile to clear the carcass end immediately it begins to open. It is, however, necessary to take the strain off the screws by recessing both carcass side and stile, tapering the recesses as shown, and a marking - gauge is first set to the total thickness at the knuckle and gauged on the face of the stile. The width of the hinge to the exact centre of the pin is then gauged on the edge of the stile and the recess cut from the full thickness at the front to the thickness of one plate at the back. The hinge is then screwed to the stile using one centre screw only, placed in position in the opening, a piece of thin cardboard placed under the door to provide the necessary clearance, the position of the hinge marked on the carcass side, the gauge reset to the width of the hinge and marked accordingly, and the recess cut from nothing at the face to the thickness of one plate at the back. The door can now be tried in with another centre screw and the setting adjusted if necessary. The full complement of screws should only be used when the setting is correct, and steel screws should be used for testing, eventually replacing with brass. In very hard woods, oak, etc., it is advisable to run in steel screws throughout and then replace with brass in the final assembly, for it is very easy to scar a slot or twist off the head of a small brass screw in difficult woods. If a screw hole has to be moved fractionally a piece of matchstick inserted in the

hole will usually provide sufficient bite, while empty cigarette-cartons are useful for shimming up hinges.

As already mentioned, it is the position of the knuckle which determines the throw of a hinge, and a preliminary test can be made by drawing a plan of the fixed section on drawing paper and the moving part on tracing paper; a pin driven through the position of the hinge-pin centre will then allow the tracing to be rotated, showing the extent of the throw. Figures 255:11-15 give various knuckle positions and the angle of opening to be expected (the hinge proportions are exaggerated for illustration purposes), and 255:16 shows the various stages in cutting in and marking out. The positioning of clock-case hinges is illustrated in 255:17, where the centre of the pin must lie on the extreme edge of the moulding with the knuckle clear of the latter.

RULE JOINT HINGE

Figure 256:2 shows the layout for the rule joint hinge used for fall flaps on gate-leg tables, etc. in which the countersinking is on the reverse side of the knuckle, with the pin centre placed in the centre of the quadrant describing the moulding. In practice, the pin is moved very fractionally to the right to give a slight clearance, or the mouldings will grind against each other.