surface of bowl with the planishing hammer

If you went on hammering too long after your bowl is shaped, the bowl would crack or perhaps break, for hammering leaves copper hard and springy. So you must soften it before you can safely hammer any more. To do this I hold the bowl over a gas range until it is red all over, then I plunge it into cold water. This heating to soften up the copper is called annealing. Repeat the hammering until the bowl takes on the shape of the design.

In this way one can get the shape desired

Now take your round top stake and put it into the vise. Place the bowl over the round top stake, and with the planishing hammer, beat the surface until it is perfectly smooth, driving the metal just hard enough to flatten the bumps made by the hammering in the wooden block. If carefully done the surface will be true and bright and covered over with brilliant facets. A skillful hammer-man can really drive the metal in any direction he may wish. In this way you make a bowl out of one piece of copper. The top of the bowl will be ragged. Cut this rough edge with a pair of shears. File the top with a smooth file until it is perfectly true. A good test to make sure of this is to lay the bowl down on a plate of glass, or hold it up against the window pane. If there are still any tiny openings left in the edge the light will be easily seen through them. More filing must be done until no light comes through from the smallest space. This done, take a piece of emery cloth and rub the edge of the bowl until the file marks disappear. If you lap the cloth over the edge your rubbing will leave a rounded edge, which is just the finish it should have.

Marking the edge of the bowl

To flatten the bottom of a bowl: Turn the bowl upside down on a bench. With a pair of dividers find the centre of the bottom of the bowl. This is done by placing one leg of the dividers against the side of the bowl and with the other making a light scratch as near the centre as you can. Change the position of the dividers to the opposite side and do the same, but be careful that the scratch is light. Repeat this until you have done it on the four sides.

Where these lines cross is the centre. With one leg of the dividers on the centre draw a circle having a diameter of about two inches. Take a wooden mallet and strike down on the centre of the circle. This will flatten the bottom. Work from both sides of the circle and keep the rounding edge just touching the circle made by the dividers. If the strokes are too heavy the bottom will bend in like the dotted lines in the sketch.

Flatten the bottom

In that case, turn the bowl up and hammer from the inside. The bowl is now ready for polishing. Mix some powdered pumice stone with water. With a woollen cloth that has been wet and then dipped into the mixture, rub the bowl. This both cleans and polishes and at the same time gives a beautiful lustre to the surface of the metal.

IV

COPPER TRAYS

How to make copper trays (used for pins, hair pins, cards, etc.).

(1) Round. (2) Square or oblong.

ROUND TRAY

Material: Piece of copper about 7 ins. square, No. 20 gauge. A hard wood block, 10 × 10 × 2 ins. thick. Tools: Carpenters' gouge chisel, dividers, steel punch, shears, round peg of wood, 6 ins. long and 1 in. in diameter.

Design: Take a large sheet of plain paper. Draw on it a 3-in. circle. Using the same centre, draw a 5-in. circle. This gives you the plan or top view of the tray. Below this view on the same sheet, draw the elevation, or edge view of the tray. You can make the tray as deep in the centre as you wish. Let's make this one ¹⁄₂ in. deep, that's a good proportion.

Hard wood peg

This is what we call a working drawing. If you are pleased with the design, you can go right on with the work, if not, you can change it to suit. You can see by the design that the tray is made by driving the centre of this square plate of copper down into a depression. In order to do this we must make a mould the exact size and shape of the tray centre. This is what the square hard wood block is used for.

Take your hard wood block. Draw diagonal lines across one face. Where these lines intersect is the centre. With your dividers, using this centre, draw a 3-in. circle. Place the carpenters' chisel anywhere on the circle and strike with a hammer, driving the chisel down into the wood about ³⁄₈ in. Do this all around the circle. Gouge out the loose wood until you have cleaned out the whole depression, being careful not to go below ¹⁄₂ in. in depth (the depth of your design). Smooth this up nicely with sand-paper. The mould is now ready for the metal plate. With the steel punch, make holes in each corner of the copper plate about ¹⁄₂ in. from the edge and just large enough to fit the wire nails. Place this plate over the mould so that the centre of the plate comes right over the centre of the mould. Fasten the four corners down with the wire nails. To drive the metal into the depression we must use something softer than a steel hammer. A hard wood peg has been found to do this best. Cut a piece about 6 in. long from the end of a broom handle. Round one end up, using a file or a carpenters' chisel to do so.

Place the rounded end of the peg on the circle of the copper plate and, with a hammer, drive the copper into the depression below it. As constant hammering hardens