A sketch of a square box is shown in Fig. 274, the body being made up in four pieces, and jointed at the corners. The lid is in form a square pyramid, and is worked up from one piece, as will be further explained.
To set out the patterns for the different parts, it will be necessary to draw the shape to which the sides of the box must be bent. This is shown on the half-sectional elevation in Fig 275.
The pattern for one side of the body is obtained by marking down a girth line, and setting along it the lengths 4 to 5, 5 to 6, etc., up to 15, as taken from the sectional elevation. It should be noticed that the lengths from 4 up to 7 are obtained by measuring around the small circle on the section, which represents the bead on the top edge of box. After the total girth is set out, then lines square to the girth line should be drawn through each numbered point. The lengths of these lines each side of the girth line should then be marked off equal to the similarly numbered lines which run from the centre line up to the curve on the section. To take one case: the line numbered 9 9 on the pattern should be the same length as the line numbered 9 9 on the half-sectional elevation. After all the lengths have been carefully cut off, then the points should be joined up with an even curve. On account of the foot having straight sides it will be noticed that the cut on the pattern which forms the foot will be made up of straight lines.
The lid of the box is pyramidal in shape, and therefore the making of the pattern is a simple matter. With radius equal to 0 1 on the elevation describe the pattern circle (Fig. 275). Draw a line touching this circle, and on each side of the point of contact cut off distances 1 A equal to the length of 1 A on the elevation. After one line A A is drawn, then the other three lines with the same letter can be drawn around the circle as shown. Strips now require to be added to form the rim of the lid. Take off the lengths 1 to 2 and 2 to 3 from the elevation, and transfer to the pattern, as seen by the same numbered lines. Now draw lines through the points parallel to A A, and cut these off to the corresponding lengths on the elevation. That is, make 2 a on the pattern the same length as 2 A on the elevation, and 3 b on the pattern the same as 3 B on the elevation. A small lap, as shown by the dotted lines, should be allowed on one edge of the lid pattern for jointing.
Now to make up the article. If made of copper or brass, it will be essential to coat the inside of the sheet metal with tin. This can be done in the ordinary way by first cleaning the surface of the metal, sprinkling over with a flux, such as salammoniac, and then putting a few bits of tin on the sheet and heating over a gas or clean coke fire, and wiping off with a piece of dry cloth or tow. To avoid the tin running on to the side of sheet that is not required to be coated, it is a good plan to first brush its surface over with some whitening paste.
In shaping the four side-pieces that go to form the body, the small bead at the top should first be put on. This can be done by bending the edge along, doubling it over a piece of wire of the right size, carefully tucking the edge in, and then withdrawing the wire. The edge at the bottom of the foot should next be folded over and lightly flattened down. Each of the four pieces can then be formed into shape, and it should be remembered in connection with this that the centre line on the pattern must conform to the exact shape of the half-sectional elevation.
Before proceeding to completely solder down any one corner, all the pieces should be tacked together, and the body tested as to shape, and also if level across the top and bottom. The edges of the sheet down the corners should be brought into contact as far as possible, so as to avoid any appearance of solder on the outside of joint. The soldering should, of course, be done down the inside of corners, a fair body of solder being left on so as to strengthen the joint. The bead around the top may also be made stronger at the corners by bending small pieces of wire at right angles, and inserting in the bead before tacking.
The pattern for the bottom is not shown, as it will be simply a square piece of sheet metal the size of which will be equal to the length of line drawn through the point 13 on the side pattern. The bottom plate will, of course, be tinned on one side, and fastened to the body by soldering all round.
The sheet metal for the lid can be brought into shape by bending along each of the corner lines marked 0 A until the end lines of the pattern come together. The joint should then be formed by fixing the lap on the inside of the lid and soldering down. The double edge to form the lid can then be bent, as shown in the sectional elevation. A hole is made in the centre of the lid, and a knob to suit the individual taste soldered in.
After cleaning away all superfluous solder, the outside of the box should be polished and coloured, lacquered, or treated in any other way suitable to the likes of the individual.
Whilst the making of a square box has been described, the above remarks will apply to a box of any number of sides, the only difference being that the pattern for the body will have to be marked out as explained in connection with the next example.