The Boy Mechanic Part 79

** Homemade Telegraph Key [283]

[Ill.u.s.tration: Key and Connections]

A piece of wood, 1/2 in. thick, 2 in. wide and 5 in. long, is used for the base of this instrument. Two wire nails, each 1 in. long, are used for the cores of the magnets. Each nail is wound with three or four layers of fine insulated magnet wire, about No. 25 gauge, similar to that used in electric bells, leaving about 1/4 in. of the end bare so that they may be driven into the wood base.

The connections for the coils are shown in the sketch, at A.

About 1 in. behind the coils is fastened a small block of wood, the top of which is just even with the top of the nails in the coils. A piece of tin, cut in the shape of the letter T, is fastened with two screws to the top of this block, and the end bent slightly so as to clear the top of the nails about 1/32 in.

The key lever is cut from a thin piece of wood, in the shape shown in the sketch, and pivoted in a slotted block which is used as a base for the key. A piece of bare copper wire is fastened along the under side of the key, as shown by the dotted lines. A rubber band, pa.s.sing over the end of the key and attached to the base with a tack, acts as a spring to keep the key open. A small piece of tin is fastened to the base under the k.n.o.b of the key. This is for making the contact between the copper on the key and the wires from the coils, when the key is pushed down.

--Contributed by W. H. Lynas.

** Protecting Sleeves [283]

Bicycle trousers-guards make excellent sleeve bands when the cuffs are turned back and rolled above the elbows.

** Imitation Arms and Armor-Part VII [284]

The helmets, breastplates and gauntlets described in parts V and VI can be used in making up a complete model

[Ill.u.s.tration: Full Suit of Armor]

for a full suit of armor of any size, as shown in Fig. 1. All of the parts for the armor have been described, except that for the legs. Figure 2 shows how the armor is modeled on the side of the left leg. The clay is modeled as described in previous chapters, the paper covering put on, and the tinfoil applied in imitation of steel. The chain mail seen between and behind the ta.s.sets is made by sewing small steel rings on a piece of cloth as shown in Fig.

3. These rings may be purchased at a hardware store or harness shop.

The whole figure when completed is placed on a square box covered with red or green baize. The armor should be supported by a light frame of wood built up on the inside, says the English Mechanic, London. Two vertical pieces are firmly attached to the box so they will extend up inside the legs, and at the top of them is attached a crosspiece on which is placed a vertical stick high enough to carry the helmet. The two lower pieces must be built up and padded out with straw, then covered with red cloth or baize to represent the legs.

In making up the various pieces for a full model it will be found very convenient to use rope, a stout cord or strings in making up the patterns on the parts. Instead of using bra.s.s-headed nails, bra.s.s paper fasteners will be found useful. These can be purchased at a stationery store. Secure the kind having a round bra.s.s head from which hang two bra.s.s tongues. These are pushed through a hole and spread out flat on the opposite side. Other materials can be used in the place of tinfoil to represent steel. Silver paper will do very well, but if either the tinfoil or silver paper are found difficult to manipulate, go over the armor with a coat of silver paint put on with a brush. When dry give the surface a coat of varnish.

** A Home-Made Tripod Holder [284]

An inexpensive tripod holder, one that will prevent the tripod from slipping on a smooth floor, and prevent the points from doing damage to the polished surface or puncturing an expensive rug or carpet, can be made in a few minutes' time, says Camera Craft.

Secure two strips of wood, or ordinary plaster laths will do, and plane them down to a thickness of 3/16 in., for the sake of lightness. Cut them to a length or 40 in. and round off the ends to improve their appearance. Take the piece shown in Fig. 1 and drill a 1/4-in. hole in the center, and eight small holes, 1 in.

apart, at each end. In one end of the piece, Fig. 2, make the same series of eight small holes and, in the other end, drill six 1/4-in. holes, 3 in. apart. A 1/4-in. flat headed carriage bolt, about 1 in. long, completes the equipment.

The two pieces are bolted together, not too tight, and the points of the tripod legs inserted in their respective small holes. So set up, there is absolutely no danger of one of the legs slipping out of position. By moving the position of the bolt from, one to another of the larger holes in the strip, Fig. 2, almost any desired inclination of the camera can be secured.

The same sort of simple apparatus built slightly stronger, and with a small caster under each of the three series of small holes, makes an

[Ill.u.s.tration: The Tripod Cannot Slip]

excellent tripod clamp for use when the camera has to be s.h.i.+fted about, as in portraiture and the like.

** How to Weave a Shoestring Watch Fob [285]

Having procured a pair of ordinary shoestrings, take both ends of one of them and force the ends through the middle of the other, leaving a loop 1-1/2 in. long, as shown in Fig. 2. In this sketch, A is the first string and B is the second, doubled and run through the web of A. Take hold of the loop and turn it as shown in Fig.

2, allowing the four ends to hang in four directions. Start with one end, the one marked A, in Fig. 1, for instance, and lay it over the one to the right. Then take B and lay it over A, and the one beneath C; lay Cover B and the one under D, and then lay D over C and stick the end under A. Then draw all four ends up snugly. Commence the next layer by laying the end A back over B and D; D over A and C; C over D and B, then B over C and the end stuck under A. Proceed in the same manner and keep on until about 1-1/2 in. of the ends remain unwoven. Four pins stuck through each corner and into the layers will hold the ends from coming apart.

The ends of the strings are raveled out so as to make a ta.s.sel.

This will make a square fob which will appear as shown in Fig. 4.

A round fob is made in a similar way, taking the same start as for the square fob, but instead of reversing

[Ill.u.s.tration: Fobs Made from Shoestrings]

the ends of each alternate layer, always lap one string, as at A in Fig. 3. over the one to its right, as B, slipping the last end of the four strings under and tightening all, as in making the square fob. Fasten the ends with pins and ravel out for a ta.s.sel.

The round fob is shown in Fig. 5.

A fob in the shape of a horseshoe can be made by taking four shoestrings and tying a small string around the middle of them, then weaving the layers both ways from the point where the strings are tied. A loop, 1-1/2 in. long, is left out at the center before starting on one side. The loop is for attaching the fob to the watch. After the weaving is complete and the ta.s.sel ends made, a small stiff wire is forced through the center to form the shape of a horseshoe.

Other designs can be made in the same manner. Strings of different colors will make up a very pretty fob, especially if silk strings are used.

--Contributed by John P. Rupp, Monroeville, Ohio.

** How to Make a Table Mat of Leather [286]

The table mat, the design of which is shown herewith, is to be made of leather. It may be made of Russian calf and the background modeled down

[Ill.u.s.tration: Pattern for the Table Mat]

as has been described in several previous articles dealing with leather work. To do this the leather is moistened on the back side just enough to make the leather take the impression of the tool, but not enough to make the moisture show through on the face. Any smooth piece of steel, such as a nut pick, that will not cut or scratch the leather and will make a V-shaped depression will do.

A second method is to secure a piece of sheepskin and, using the reverse side, outline the design by means of a pyrographer's outfit. This manner of treating leather is so common that it needs no description.

A third method is to secure a piece of sheep or goat skin, trace the design on the reverse side by means of carbon paper, and put the outline and design in with brush and stains such as are sold for this purpose.

The accompanying pattern shows but one-fourth of the mat. Draw the one-fourth on paper to the size desired and then fold on lines A and B, tracing this one-fourth on the other parts by the insertion of double-surfaced carbon paper.

On the calfskin the pattern is to be held on the leather and the tool worked over the pattern to get the outline transferred. After this the pattern is to be removed and the leather modeled.

** Sad Iron Polisher [286]

A small amount of wax is necessary on an iron for successful work.

The wax is usually applied by hand to the heated surface of the iron. A much better and handier way is to bore five or six holes in one end of the ironing board to a depth of half

[Ill.u.s.tration: Polisher]

its thickness, filling them with wax, beeswax or paraffin, and covering them over with two thicknesses of muslin.