Buttoning.—The tops of tables, sideboards, etc., should not be fixed with screws in the ordinary way. At the front, screws can be driven upwards through the top rail, but at the sides and back, buttons should be employed, as in [Fig. 359], so that the top is free to shrink. It is otherwise liable to split if immovably fixed. The tops of kitchen tables are usually fixed in this way, to allow for shrinkage.
Fig. 359.—Method of Buttoning a Table Top.
Frames for Oil Paintings.—The method of making joints for frames on which the canvas is stretched for oil paintings is shown at [Fig. 360]. They are generally mitred at the corners and fitted with loose wedges. The four parts of the frame can be held temporarily by a piece of thin board while the canvas is being tacked to the edges of the frame. In the accompanying illustrations [Fig. 360] shows the action of the wedges when tightening up the frame, the result being to open the mitre joint. [Fig. 361] shows the position of the saw cuts for receiving the hardwood wedges. Note that the parallel groove is carried the full length of the material for greater convenience in cutting. The other groove is taken from the outer angle of the mitre joint inwards. The cut finishes with due regard to the necessary taper; see the dotted lines showing taper in [Fig. 360]. The grooves will be wide enough after being cut with an ordinary hand-rip saw, but for large work they are usually grooved on the circular saw bench.
| Fig. 360. | Fig. 361. |
Joint and Method of Wedging the Frames of Oil Paintings.
Corrugated Steel Fasteners.—It is now many years ago since the steel saw-edge fastener first appeared on the market, but probably 80 per cent. of amateur woodworkers have never yet sampled its advantages.
In appearance it resembles a miniature corrugated galvanised sheet such as is used for roofing purposes, with the exception, however, that the corrugations are divergent instead of being parallel and that one end is ground down to a cutting edge (see [Fig. 363], A). They are made in various sizes from 1⁄4 in. to 1 in. in length, whilst in regard to width they are classed by the number of corrugations and not by their measurement.
| Fig. 362.—Jointing Boards. | Fig. 363.—Jointing a Frame. |