Part 24 (2/2)

[Ill.u.s.tration: Fig. 288. Door, Ill.u.s.trating Panel Construction: S.

Stile; T. R. Top Rail; L. R. Lock Rail; B. R. Bottom Rail; M. Muntin; P. Panel; A. Double Mortise-and-Tenon; F. Fillet; A. B. C. Forms of Panels.]

The joint commonly used is the haunched or relished mortise-and-tenon, Fig. 267, No. 42, p. 180; (See p. 163 for directions for making). The tenon is sometimes doubled, Fig. 288, and a fillet (f) may be inserted to cover the ends of the tenons, or the joint may be a blind mortise-and-tenon, Fig. 266, No. 32, or in cheap construction, dowels may be used. The best doors are now made with cores of pine covered on the visible sides with heavy veneer. Large surfaces are covered by increasing the number of parts rather than their size, as in wainscoting.

Picture-frames also belong in this cla.s.s of structures, the gla.s.s taking the place of the panel. They are made with mortise-and-tenon joints, Fig. 266, No. 33, slip joints, Fig. 267, No. 46, dowelled b.u.t.t joints, Fig. 264, No. 8, end lap joints, Fig. 265, No. 17, and, far more commonly, mitered joints, Fig. 268, No. 52. Mitered joints are the easiest to make, for the joints can be cut in a miter-box, Fig.

181, p. 104, and glued in a picture-frame-vise, Fig. 172, p. 101. This joint needs reinforcement by nails, Fig. 268, No. 52, by dowels, No.

53, or by splines, No. 55. If the sides are of different widths, the fitting of the joint is more difficult. Mitered joints are the only kind suitable for molded frames. The rabbets are cut out with a rabbeting-plane before mitering and a.s.sembling.

The principle disadvantage of a mitered joint is that, if the wood shrinks at all, it opens at the inside corners, as in Fig. 289, because wood shrinks sidewise but not lengthwise.

[Ill.u.s.tration: Fig. 289. The Way a Mitered Joint Opens on Account of Shrinkage.]

In window sashes, the dovetail joint, Fig. 267, No. 47, is the common one at the upper end of the lower sash and the lower end of the upper sash, and the mortise-and-tenon joint modified is used at the lower end of the lower and upper end of the upper sash. The gla.s.s takes the place of the panel. In blind sashes, the pinned mortise-and-tenon joint, Fig. 267, No. 38, is commonly used.

When panels are joined together to enclose a s.p.a.ce, then we have what is properly called cabinet construction. Ill.u.s.trations are cabinets, bureaus, desks, lockers, chests, etc.

In all these cases, the constructed panels may be treated as separate boards and joined together with dowel pins or splines or dadoed together without any other framework, tho the corners are often reinforced by cleats or blocks glued into them. Sometimes, however, as in chests, Fig. 290, posts are used instead of stiles, and rails are mortised or doweled into them and the panels set into grooves in both posts and rails. In this case the bottom is raised from the floor, and may be dadoed into the bottom rails, or dowelled into them or even supported by strips attached along their lower inside edges. The chest really is a union of both paneled and framed structures.

[Ill.u.s.tration: Fig. 290. Chest Construction.]

(4) FRAMED STRUCTURES

The principle of the framed structure is similar to that of the panel construction in that the object is to allow for shrinkage without harm to construction and also to economize materials. Common examples are tables, chairs, work-benches, and frame houses.

_The Making of a Table._ The standard height of a table is 30”. There should be 25” clearance under the rails. This leaves approximately 4” for the width of the rails. a.s.suming that the table is to be of a simple straight line type with one drawer, the following method of procedure is suggested:

Cut the boards for the top to the approximate length and stick, (see p. 47) and clamp them, so as to season them as well as possible before jointing.

Dress to size the legs and rails. Stand the legs in their proper positions relative to each other, and mark them F R (front right), F L (front left), B R (back right), and B L (back left). Plow out the grooves on the inside of the rails for the fastenings of the top, Fig. 297, D, if they are to be used. Lay out and cut the tenons and mortises for the end rails and back rail.

The proper form of the tenon is one with a wide shoulder above it so that the top of the leg above the mortise will not shear out. The rails should be set near the outside of the leg so that the tenon may be as long as possible and the portion of the leg inside it as strong as possible. A haunched mortise-and-tenon joint, Fig. 267, No. 43 is sometimes used, giving additional lateral stiffness to the rail. The proper proportions are shown in Fig. 291. When cut, these parts should be temporarily a.s.sembled to see if they fit.

[Ill.u.s.tration: Fig. 291. A. Cross-Section Thru Back Left Leg and Adjoining Rails of Table. (Plan). B. Elevation, Showing Wide Shoulder on Tenon of Rail.]

Inasmuch as a drawer takes the place of a front rail, the front legs must be tied together in some other way. For this purpose two stringers or drawer rails may be used, their front edges being as far from the face of the legs as are the rails from the side and back. The upper drawer rail may be dovetailed at both ends into the tops of the legs, as shown in Fig. 292. If this takes more room than can well be spared from the depth of the drawer, it may be omitted, but it adds greatly to the stiffness of the table and is an excellent means of fastening on the top by the use of screws pa.s.sing thru it.

[Ill.u.s.tration: Fig. 292. Table Construction: Upper Drawer Rail of Table Dovetailed into Left Front Leg.]

The drawer rail, also called the fore edge, is long enough to partly overlap the side rails, into the lower edges of which it is gained so as to be flush with them, and may be fastened to them with screws, Fig. 293. The construction may be further strengthened by also doweling the end of this stretcher into the legs. If there are two drawers, the part.i.tion between them may be doweled or gained into these upper and lower stretchers.

[Ill.u.s.tration: Fig. 293. The Fixing of a Drawer Rail, Seen From Below.]

If the legs are to be tapered or otherwise shaped, that should be done next. Then glue and a.s.semble the end rails with their proper legs, taking care to see not only that the joints come up square, but that the legs are in the same plane. Finally a.s.semble the whole, inserting, if necessary, a temporary diagonal brace to insure squareness, Fig.

294. When dry, clean up the joints. For the making of a table drawer, see above, p. 191.

[Ill.u.s.tration: Fig. 294. Brace to Insure Right Angles in a.s.sembling a Framed structure.]

To fit the drawer to its place, runners and guides, Fig. 295, must first be fastened in. The runners are in line with the drawer rail, and are glued and nailed or screwed to the side rails between the back of the lower stringer and the back posts. On top of them and in line with the inner face of the legs are the guides running between the front and back posts. Or the runner and guide may be made of one piece properly rabbeted out.

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