At the cost of oversimplification, it will be the aim of this volume to present mechanical effects which depend upon elementary principles for successful operation. Homecrafters possessing mechanical experience or aptitude will encounter little difficulty in applying their knowledge of rudimentary gears, worms, or pinions to elaborate on the simple mechanical principles discussed in the following pages.

The majority of motivated toy figures described herein depend, in great part, upon the basic principle of eccentric action for their effects. The simplest example is the kangaroo in Figure 2.9, which achieves a hopping motion when it is pulled or pushed, simply because the axles of one pair of wheels is mounted off-center.

In Figure 3.8, Moby Dick the whale dives languidly up and down because his unpivoted front end rides directly upon an eccentrically mounted cam attached to the front wheels. This focuses attention upon the matter of the "fixed axle," for it is evident that in order to impart motion to the cam, the latter must be attached either to the wheels themselves or to an axle which is "fixed" to the wheels so that it will rotate with them in its housing or bearings.

Another modification of eccentric action which is frequently employed is that provided by a crank permanently bent into an axle which, as it rotates with the wheels, pulls a cord or pushes a wire attached to a movable part or parts of the figure. This method is clearly illustrated in Figure 3.11, where the bent ends of the wire axle are "fixed" directly to the wheels. If the wheels are equipped with spokes, the ends of the axle may be bent around a spoke of each wheel at the hub.

Finish

After all surfaces have been rendered splinterproof and smooth, and all sharp edges and corners have been rounded or at least beveled, the next question to be considered is that of finish. Both children and grownups are partial to bright colors during recreational periods, and for the very young, primary colors are least confusing. Obviously, if the finish is to be in colors, the paints or enamels used should be selected for their capabilities of withstanding destructive testings by youthful owners of the toys and games.

Enamels are procurable in the bright primary colors and, when properly applied, will present a hard, glossy finish which will offer considerable resistance to normal misuse. The hardness of the final film is in part dependent upon the application of a suitable undercoater, which will seal and fill up the pores in the bare wood. Prepared undercoaters are procurable at paint stores or, if necessary, can be improvised by mixing eight parts of flat white paint with one part of enamel. Although enamel undercoater only comes in white, it can and should be tinted to approximate the final color used. This can be done by adding an ounce or so of pigment ground in oil to the gallon of white undercoat.

The undercoat, when dry, should be sanded lightly to provide a "tooth" for the succeeding coat of enamel to adhere to. Prior to sanding, all cracks and undesirable depressions should be filled in with plastic wood or one of the putties. An ideal finish includes an intermediate (second) coat of half enamel and half undercoater, which is also sanded lightly with 3/0 paper before the final coat of pure enamel is flowed on.

When applied by brush, enamels and pigmented lacquers must be flowed on, rather than brushed out like paint. Spraying is the ideal method for applying pigmented lacquer (enamel) and will produce an even coat of varnish enamel, if the latter is sufficiently thinned to permit a smooth flow through the nozzle of the spray gun.

In finishing small toys and games with a sprayer, an empty cardboard carton will make a useful spray booth, provided the surrounding floor or table is covered with newspapers. In order to avoid embedding dust particles in the object being sprayed, it is customary to do the spraying indoors, to avoid air currents laden with dust. It is well to remember, therefore, that the spray particles themselves are highly inflammable; this is particularly true of lacquer.

When there is poster paint on hand and time is of the essence, or enamels are difficult to obtain in the desired colors, a very satisfactory finish can be mixed by adding a little glue to tempora to keep it from rubbing off. A final coat of shellac will provide additional hardness.

Natural Finish

If it is decided to dispense with colors, or to use them only on certain parts, a wooden toy or game can be finished with shellac, varnish, or lacquer, with or without a preliminary stain, depending upon the grain of the wood. Shellac, while quick to dry, is equally quick to wear off as a final finish; it makes a good sealer for close grained woods, however, when well thinned with alcohol.

Coarse grained woods will look better, and their finishes will last longer, if their pores are well filled. Ready prepared paste fillers are entirely satisfactory and are obtainable in stock shades. They are easy to apply by wip>-ing across the grain with a piece of burlap. After thoroughly drying, the surface should be lightly sanded, then sealed before the final finish is applied.

Spar varnish is probably the most elastic and hence the most durable of the transparent finishes. In addition, it is highly weather resistant, which is a boon to toys which have been taken outdoors and then forgotten. Because of its transparent nature, it can be applied over soft paint or tempora with only a slight deepening of the colors.