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قراءة كتاب Woodwork Joints: How they are Set Out, How Made and Where Used.

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Woodwork Joints: How they are Set Out, How Made and Where Used.

Woodwork Joints: How they are Set Out, How Made and Where Used.

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دار النشر: Project Gutenberg
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taken to first plane up the boards true on one side—i.e., take them out of winding. The method of testing for this is shown at Fig. 9, and it may with advantage be used when jointing the edges of the boards. Two laths or strips of wood are planed up to exactly the same width, having their edges straight and parallel. One edge of each lath may, if desired, be bevelled a little. The method of using these "twist sticks" or "winding laths" is to put them on the board as indicated, and sight along their top edges. The winding laths, being much longer than the width of the board, show up the irregularity greatly pronounced.

The Tools generally used for making the butt joints are:—

The jack plane, for roughing the edges, etc.

The wooden trying plane (or iron jointing plane) for trueing up the work.

The try square for testing purposes.

The winding laths and straight edge.

The Method of Work is as follows: Each board is in turn put in the vice and planed straight lengthwise; it is then tested with winding laths and a try square (the latter method is shown at Fig. 22).

Fig. 9.—Testing Surface with Winding Laths.Fig. 9.—Testing Surface with Winding Laths.

The boards are then put on the top of one another as at Fig. 1 and tested with a straight edge; they should appear true as shown at Fig. 3; if they show faulty as at Fig. 4 the joints must be again fitted until the required degree of accuracy is obtained. Difficulties may be avoided by care in selecting timber suitable for jointing, and it must be remembered that timber shrinks circumferentially (the heart side becoming curved) as dotted lines in Fig. 10. If the timber be jointed with all the heart side one way as at Fig. 10, the tendency will be for it to cast as shown by the dotted line. If the timber be alternated as at Fig. 11, the tendency will be to cast wavy, whereas if quartered timber can be obtained it will stand practically straight as the tendency to shrink is in thickness only. The grain of quartered timber is shown in Fig. 12.

Fig. 10.—Showing Heart side of Timber one way.Fig. 10.—Showing Heart side of Timber one way.
Fig. 11.—Heart side of Timber shown alternated.

Fig. 11.—Heart side of Timber shown alternated.

Fig. 12.—Grain of Quartered Timber.

Fig. 12.—Grain of Quartered Timber.

Fig. 13.—Boards showing uniformity of Grain.Fig. 13.—Boards showing uniformity of Grain.

Judgment should also be exercised to avoid jointing in which one piece of timber is wild and large in the grain, and the adjoining piece of a mild-grained nature. Jointed boards should always be glued up with the grain running in the same direction if possible; this we show at Fig. 13, and nothing looks worse than a dressing chest end or similar piece of work in which the grain runs haphazard. When jointing thin timber (say, 14-in., 38-in., 12-in. and 58-in. boards) the best method is to use a shooting board (Fig. 26). It must be noted, however, that a shooting board and plane practically never give a true right angle, owing to wear and the grinding of the blade. Therefore, the boards should not all be laid with the "face mark" on the shooting board whilst the edges are shot, because any inequality would be multiplied by the number of pieces jointed. A better method is to alternate the boards, face side up, then face side down, whilst shooting the edges; this will prevent convexity or concavity on the face of the jointed board, because any slight error in the angle is neutralised (see Fig. 8).

Applications of the Joint.—The following show various applications of the butt or glued joint:—

Fig. 14.—Carcase Wing-pieces Glued on.Fig. 14.—Carcase Wing-pieces Glued on.

Fig. 7A shows a mahogany or other hardwood slip glued on the edge of a cheaper wood, such as pine or whitewood, as is the case on bookcase shelves when only the front edge is seen and polished.

Fig. 7B shows a moulding glued on a shelf, both mould and shelf in this instance being of polished hardwood. A shelf of this type might be used in a recess, the object of the overhanging moulding being to hide a small 38-in. iron rod which would carry the curtain rings and heading of

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