The Boy Mechanic Part 77

** An Electric Engine [276]

The parts of this engine are supported on a base 3/4 in. thick, 4 in. wide and 7 in. long. The upright B, Fig. 1,

[Ill.u.s.tration: Shaft Turned by Magnetism]

which is 1/2 in. thick and 3 in. high, is secured across the base about one-third of the distance from one end and fastened with a wood screw put through from the under side. The magnet core C is made of a carriage bolt, 2-1/2 in. long, which is fastened in a hole in the top part of the upright B so that the end C will protrude slightly. Before placing the bolt in the hole of the upright, slip on two cardboard washers, each 1 in. in diameter, one at the head end and the other against the upright B. Wrap a thin piece of paper around the bolt between the washers and wind the s.p.a.ce full of No. 22 gauge magnet wire, allowing each end to project for connections.

The driving arm D, Figs. 1 and 3, is made of a piece of soft sheet iron, 1/2 in. wide and 3 in. long. A small block is fastened to the lower end of the metal and pivoted between two uprights, 1/2 in. high, which are fastened to the base. The uprights on each side of the block are better shown in Fig. 3.

Two supports, each 1/2 in. thick and 3 in. high, are fastened with screws about half way between the end of the base and the upright B, Fig. 1. The end view of these supports is shown in Fig. 2, at GG. A 1/8-in. hole is bored through the top part of each support so they will be in a line for the axle. The axle is made of a piece of steel 1/8 in. in diameter and about 4 in. long. An offset is bent in the center, as shown, for the crank. A small flywheel is attached to one end of the shaft. The connecting rod E, Fig. 1, is made of wood and fastened to the upper end of the driving arm D with a small screw or nail. The contact F is made of a strip of copper, 14 in. wide. This is to open and close the circuit when the engine is running. The connections are made as shown in Fig.

1.

Connect two dry cells to the binding-posts and turn the flywheel.

The current pa.s.sing through the magnet pulls the driving arm toward the bolt head, which gives the shaft a half turn. The turning of the shaft pulls the arm away from the copper piece F, causing a break in the current. As the shaft revolves, the arm is again brought back against the copper strip F, thus the current is broken and applied at each revolution of the shaft. --Contributed by S. W. Herron, Le Mars, Iowa.

** Child's Home-Made Swing Seat [276]

A very useful swing or seat for children can be made from a box or packing case. Procure a box of the right size and saw it out in the shape shown in the ill.u.s.tration. The ap.r.o.n or board in front slides on the two front ropes. The board can be raised to place the

[Ill.u.s.tration: Made of a Box]

child in the box and to remove him. The ropes are fastened to the box by tying knots in their ends and driving staples over them.

** Clay Flower Pots Used for Bird Houses [277]

A novel use of the common garden flower pot may be made by enlarging the small opening at the bottom with a pair of pliers, and carefully breaking the clay away until the opening is large enough to admit a small bird.

Place the pot, bottom side up, on a board, 3 in. wider than the diameter of the largest pot used, and fasten it to the board with wood cleats and bra.s.s screws. Fit the cleats as close as possible to the sides of the pot. One or more pots may be used, as shown in the sketch.

The board on which the pots are fastened is nailed or screwed to a post or pole 10 or 12 ft. in height. The board is braced with lath or similar strips of wood, making a framework suitable for a roost. In designing the roost, the lath can be arranged to make it quite attractive, or the braces may be of twigs and branches of a tree to make a rustic effect.

--Contributed by William F. Stecher, Dorchester, Ma.s.s.

[Ill.u.s.tration: Pots Fastened to the Board]

** Location of a Gas Meter [277]

The gas meter should not be located in a warm place or the gas will expand before the meter measures it and the gas bill will be proportionately increased. Gas expands by about 1/491 part of its volume for each deg. F. that it is heated. If the meter is warmed 10 deg. F., it will make the gas cost over 2 per cent more, without any corresponding benefit.

** How to Make Rope Grills [277]

Beautiful and useful household ornaments, grills and gratings for doors, windows, shelves, odd corners, etc., can be made by the following method at a slight cost and by anyone possessing a little ingenuity. The materials required are rope or, preferably, common window cord (called sash cord) about 5/16 in. in diameter; ordinary glue, paraffin and paint or varnish. A few strips of wood or molding are very handy to use around the edges.

The design must be considered first and when one is selected, if it is other than straight lines, adopt the method described.

Take a smooth flat board and layout the design or designs which, when combined, will produce the pattern desired. Drive finis.h.i.+ng nails at the angle points or along curves as required. Coat the board along the lines of the patterns with melted paraffin, using an ordinary painter's brush to prevent the ropes from sticking to the boards after they are soaked in glue and run around the nails.

Soak the sash cord in common glue sizing for a short time, then bend or twist it along or around the lines desired, as shown in Fig. 1, and give it time to dry. The bottom part of the sketch, Fig. 1, shows a method of winding the rope on a round stick to make circular objects. Wind the

[Ill.u.s.tration: Fig. 2-Designs for Grills]

desired number of turns and when dry, cut and glue them together.

[Ill.u.s.tration: Fig. 1-Method of Forming the Rope]

In Fig. 2, six designs are shown. These suggest ideas in making up combinations or in plain figures and the number is limited only by the ingenuity of the designer.

--Contributed by Geo. M. Harrer, Lockport, N. Y.

** A Simple and Effective Filter [278]

Procure an ordinary lamp chimney and fit two or three thicknesses of cheese cloth over the end of it. Press a tuft of absorbent cotton into the small part of the neck to a depth of about 3 in.

Insert the chimney in a hole cut in a wood shelf used as a support. Pour the water in until the filter is filled, when it will be observed that any organic matter, chips of iron rust, etc., will be retained by the cotton. The fine organic matter may penetrate the cotton for about 1 in., but no farther. The resultant filtered water will be clear and pure.

[Ill.u.s.tration: Filter]

** Cutting Tools [278]

The cutting point of a tool should never be below the centers.

** Imitation Arms and Armor-Part VI [279]

A ma.s.s of any kind of clay that is easily modeled and fairly stiff must be prepared and kept moist and well kneaded for making the models over which paper is formed to make the shape of the articles ill.u.s.trated in these sketches. A modeling board must be made of one large board or several pieces joined closely together upon which to work the clay, says the English Mechanic, London.

The size of the board depends upon the size of the work to be made.

[Ill.u.s.tration: Armor and Clay Models]

An open chamfron of the fifteenth century is shown in Fig. 1. This piece of horse armor, which was used in front of a horse's head, makes a splendid center for a s.h.i.+eld on which are fixed the swords, etc., and is a good piece for the amateur armorer to try his hand on in the way of modeling in clay or papier mache work.

The opening for the animal to put his head into is semicircular, and the sides do not cover the jaws. As the main part of this armor is worn in front of the head the extreme depth is about 4 in. The entire head piece must be modeled in clay with the hands, after which it is covered with a thin and even coating of sweet or pure olive oil. A day before making the clay model some pieces of thin, brown wrapping paper are torn in irregular shapes to the, size of the palm of the hand and put to soak in a basin of water in which a tablespoonful of size has been dissolved. If size cannot be obtained from your local painter, a weak solution of glue will do equally well. All being ready, and the clay model oiled, take up one piece of paper at a time and very carefully place it on the surface of the model, pressing it on well and into and around any crevices and patterns. Continue this operation until the clay model is completely covered on every part. This being done, give the paper a thin and even coating of glue, which must be quite hot and laid on as quickly as possible. Lay on a second layer of paper as carefully as before, then another coat of glue, and so on until there are five or six coats of glue and paper. When this is dry it will be strong enough for all ornamental purposes. The ragged edges of the paper are trimmed off with a sharp knife and the whole surface smoothed with fine sandpaper. Then carefully glue on sections of tinfoil to give the armor the appearance of steel. The armor is now removed from the model.

A mitten gauntlet of the fifteenth century is shown in Fig. 2.

This can be made in one piece, with the exception of the thumb s.h.i.+eld, which is separate. The thumb s.h.i.+eld is attached to the thumb of an old glove which is fastened with round headed nails on the inside of the gauntlet.

[Ill.u.s.tration: Corrugated Breastplate and Former]