Fig. 162. The drawing of the plan shows only one side of the long diagonal covered by the thin pieces of the parquetry, but the other side is left blank merely to reveal the foundation of yellow deal. In the bench work the whole surface should be covered, and the alternation of colours by the arrangement of dark and light-coloured strips repeated on the blank side. Observe that the opposite angles of the rhombus must agree in the arrangement of colour.

The parquetry can be made very effectively of mahogany 3/8 in. thick, and sycamore, or some woods giving good colours.

It is not advisable to specify the precise dimensions of the wood required to make the base of this exercise, as much waste would arise in cutting up the timber, which may be avoided by sawing out the diamond-shaped pieces, having sides about 65/8 ins. long, for several models, from a board 5 3/4 ins. wide.

The drawing shows the grain of the wood running parallel to the edge, and if the wood is cut up so as to give this result, the appearance of the complete exercise is much better than if it is not attended to.

Side elevation.

Plan with parquetry removed on one half.

Fig. 1G2.

A strip of mahogany 2 ins. wide, planed to a thickness of 5/16 in. and of 2 ft. or 3 ft. in length, may be cut up into small triangular pieces, as in fig. 163, and to the dimensions shown, two being required for each exercise. A similar strip of sycamore may be cut up in the same way to give the light-coloured inner triangles.

Fig. 163.

The outer fillets may be cut from long strips of mahogany and sycamore 1 in. wide, and planed up true to 5/16 in. thickness, in the same manner as shown in fig. 164. The edges of the fillets should now all be planed true and parallel.

Fig. 164.

Take a triangle of mahogany and a fillet of sycamore, or vice versa, and prepare them for jointing by planing the edges in the same way as for the elliptical plate, pp. 197-8. Glue them together, simply rubbing them till the glue ' sets,' and then lay the jointed piece aside, and glue the remaining pieces together in the same way - they need not be cleated while drying. Now true the face and opposite sides of the deal base of the parquetry, but do not touch the edges yet. When the glue of the joints already made is quite dry, clean off the rough pieces of glue with a jack plane, and place one of the triangles on the shooting board against a stop screwed down at an angle of 30° to the edge, as in fig. 165; plane off the side true, using the plane in the direction of the arrow, to avoid breaking the joint already made.

Shoot the remaining three triangular plates on the same edges, and test the accuracy of the angles by placing three of them together in the angle of a try square, lying flat on the bench, when, of course, they should exactly fill the right angle between the blade and stock.

If the result of the testing is unsatisfactory, the shooting board may be regarded as in error, and the stop should be taken oft and rescrewed to the board, as may be required to make the angle correct. Having made the 30° angles of each piece, take off the stop and screw it down again at 60° to the edge, and in the same way as before, plane up the 60° angles of the pieces.

The method of testing the accuracy of these angles is to place three of them together and try the outside edge with a straightedge. If any error is apparent, re-adjust the stop on the board and plane the strips up again till correct.

When all the inner right angles of the triangles are made, place them together to test finally the accuracy of the joint of the whole plate, and presuming they are correct, as they should now be, proceed to glue the pieces down on the surface of the wood one at a time, taking care to leave a margin of the deal foundation projecting all round, and the inner joints true and close, with no dark lines of glue showing. There is no need to wait for the drying of each piece before glueing down the next. They may be put down immediately after each other.

Fig. 165.

Fig. 166 shows the glued up exercise, with the projection of the foundation all round.

Into this ledge nails are driven a little distance, as shown, as close as possible to the edge of the parquetry, and as they are driven in, these will tighten up the joints and serve instead of a cleat, the use of which is not practicable in this exercise.

When the joints are quite dry, the nails should be withdrawn and the outside edges shot true with the wood screwed up in the vice.

The shooting board may be used for this edge planing, but boys are frequently not strong enough to do the work well in this case; and having greater power over the plane as it is ordinarily used, the pupils should be allowed to screw the model in the vice and shoot the edges in the usual way.

The model being now practically finished, clean off the glue with the jack plane, and then finish up true and smooth on both sides and edges, with trying plane and smoothing plane.

Fig. 1G6.