The Boy Mechanic Part 2

** How to Make Comer Pieces for a Blotter Pad [8]

To protect the corners of blotting pads such as will be found on almost every writing desk, proceed as follows:

First, make a design of a size proportionate to the size of the pad and make a right-angled triangle, as shown in Fig. 1, on drawing paper. Leave a small margin all around the edge and then place some decorative form therein. Make allowance for flaps on two sides, as shown, which may later be turned back and folded under when the metal is worked. It should be noted that the corners of the design are to be clipped slightly. Also note the slight overrun at the top with the resulting V-shaped indentation.

To make a design similar to the one shown, draw one-half of it, then fold along the center line and rub the back of the paper with a knife handle or some other hard, smooth surface, and the other half of the design will be traced on the second side. With the metal shears, cut out four pieces of copper or bra.s.s of No. 22 gauge and with carbon paper trace the shape and decorative design on the metal. Then cut out the outline and file the edges smooth.

Cover the metal over with two coats of black asphaltum varnish, allowing each coat time to dry. Cover the back and all the face except the white background. Immerse in a solution of 3 parts water, 1 part nitric acid and 1 part sulphuric acid. When the metal has been etched to the desired depth, about 1-32 of an inch, remove it and clean off the asphaltum with turpentine. Use a stick with a rag tied on the end for this purpose so as to keep the solution off the hands and clothes. The four pieces should be worked at the same time, one for each corner.

It remains to bend the flaps. Place the piece in a vise, as shown in Fig. 2, and bend the flap sharply to a right angle. Next place a piece of metal of a thickness equal to that of the blotter pad at the bend and with the mallet bring the flap down parallel to the face of the corner piece, Fig. 3. If the measuring has been done properly, the flaps

[Ill.u.s.tration: Manner of Forming the Plates]

ought to meet snugly at the corner. If they do not, it may be necessary to bend them back and either remove some metal with the shears or to work the metal over farther. All the edges should be left smooth, a metal file and emery paper being used for this purpose.

If a touch of color is desired, it may be had by filling the etched parts with enamel tinted by the addition of oil colors, such as are used for enameling bathtubs. After this has dried, smooth it off with pumice stone and water. To keep the metal from tarnis.h.i.+ng, cover it with banana-oil lacquer.

** Boring Holes in Cork [8]

The following hints will be found useful when boring holes in cork. In boring through rubber corks, a little household ammonia applied to the bit enables one to make a much smoother hole and one that is nearly the same size at both openings. The common cork, if rolled under the shoe sole, can be punctured easily and a hole can be bored straighter. The boring is made easier by boiling the cork, and this operation insures a hole that will he the desired size and remain the size of the punch or bit used.

** Self-Lighting Arc Searchlight [9]

A practical and easily constructed self-lighting arc searchlight can be made in the following manner: Procure a large can, about 6 in. in diameter, and cut three holes in its side about 2 in. from the back end, and in the positions shown in the sketch. Two of the holes are cut large enough to hold a short section of a garden hose tightly, as shown at AA. A piece of porcelain tube, B, used for insulation, is fitted tightly in the third hole. The hose insulation A should hold the carbon F rigidly, while the carbon E should rest loosely in its insulation.

The inner end of the carbon E is supported by a piece of No. 25 German-silver wire, C, which is about 6 in. long. This wire runs through the

[Ill.u.s.tration: Arc in a Large Can]

porcelain tube to the binding post D. The binding post is fastened to a wood plug in the end of the tube. The tube B is adjusted so that the end of the carbon E is pressing against the carbon F. The electric wires are connected to the carbon F and the binding post D. A resistance, R, should be in the line.

The current, in pa.s.sing through the lamp, heats the strip of German-silver wire, causing it to expand. This expansion lowers the end of the carbon E, separating the points of the two carbons and thus providing a s.p.a.ce between them for the formation of an arc. When the current is turned off, the German-silver wire contracts and draws the two carbon ends together ready for lighting again. The feed can be adjusted by sliding the carbon F through its insulation.

A resistance for the arc may be made by running the current through a water rheostat or through 15 ft. of No. 25 gauge German-silver wire.

--Contributed by R. H. Galbreath, Denver, Colo.

** A Traveler's Shaving Mug [9]

Take an ordinary collapsible drinking cup and place a cake of shaving soap in the bottom ring. This will provide a shaving mug always ready for the traveler and one that will occupy very little s.p.a.ce in the grip.

** Homemade Snowshoes [9]

Secure four light barrel staves and sandpaper the outside smooth.

Take two old shoes that are extra large and cut off the tops and heels so as to leave only the toe covering fastened to the sole.

Purchase two long book straps, cut them in two in the middle and fasten the ends on the toe covering, as shown in Fig. 1. The straps are used to attach the snowshoe to the regular shoe. When buckling up the straps be sure to leave them loose enough for the foot to work freely, Fig. 2. Fasten the barrel staves in pairs, leaving a s.p.a.ce of 4 in. between them as shown in Fig. 3, with thin strips of wood. Nail the old shoe soles to crosspieces

[Ill.u.s.tration: Made from Barrel Staves]

placed one-third of the way from one end as shown. --Contributed by David Brown, Kansas City, Mo.

** Fish Signal for Fis.h.i.+ng through Ice [10]

Watching a fish line set in a hole cut in the ice on a cold day is very disagreeable, and the usual method is to

[Ill.u.s.tration: Bell and Battery in a Box]

have some kind of a device to signal the fisherman when a fish is hooked. The "tip ups" and the "jumping jacks" serve their purpose nicely, but a more elaborate device is the electric signal. A complete electric outfit can be installed in a box and carried as conveniently as tackle.

An ordinary electric bell, A, Fig. 1, having a gong 2-1/2 in. in diameter, and a pocket battery, B are mounted on the bottom of the box. The electric connection to the bell is plainly shown. Two strips of bra.s.s, C, are mounted on the outside of the box. The bra.s.s strips are shaped in such a way as to form a circuit when the ends are pulled together. The box is opened and set on the ice near the fis.h.i.+ng hole. The fish line is hung over a round stick placed across the hole and then tied to the inside strip of bra.s.s.

When the fish is hooked the line will pull the bra.s.s points into contact and close the electric circuit.

** Homemade Floor Polisher [10]

A floor polisher is something that one does not use but two or three times a year. Manufactured polishers come in two sizes, one weighing 15 lb., which is the right weight for family use, and one weighing 25 lb.

A polisher can be made at home that will do the work just as well.

Procure a wooden box such as cocoa tins or starch packages are s.h.i.+pped in and stretch several thicknesses of flannel or carpet over the bottom, allowing the edges to extend well up the sides, and tack smoothly. Make a handle of two stout strips of wood, 36 in. long, by joining their upper ends to a shorter crosspiece and nail it to the box. Place three paving bricks inside of the box, and the polisher will weigh about 16 lb., just the right weight for a woman to use. The polisher is used by rubbing with the grain of the wood.

--Contributed by Katharine D. Morse, Syracuse, N. Y.

** Tying Paper Bag to Make a Carrying Handle [10]

In tying the ordinary paper bag, the string can be placed in the paper in such a way that it will form a handle to carry the package, and also prevent any leakage of the contents. The bag must be long enough for the end to fold over as shown in Fig. 1.

The folds are made over the string, as in

[Ill.u.s.tration: Stages in Tying a Bag]

Fig. 2. The string is then tied, Fig. 3, to form a handle, Fig. 4.

--Contributed by James M. Kane, Doylestown, Pa.

** Equilibrator for Model Aeroplanes [11]

On one of my model aeroplanes I placed an equilibrator to keep it balanced. The device was attached to a crosspiece fastened just below the propeller between the main frame uprights. A stick was made to swing on a bolt in the center of the crosspiece to which was attached a weight at the lower end and two lines connecting the ends of the planes at the upper end. These are shown in Fig.

1. When the aeroplane tips, as