Fig. 10. Fig. 11. Fig. 12.
Parallel Bars
The regulation parallel bars are usually supported on iron pipe-standards bolted to a heavy base, and steel heads are provided to grip the bars. But this fitting is beyond the ability of a boy to construct without the aid of a plumber, and the wooden frame base and bars shown in Fig. 12 will answer quite as well.
The bars are of hickory, five and a half feet long and two inches in diameter. The uprights that support them are of oak, ash, or other hard-wood, two and a half inches square and forty-two inches long. The lower ends of the uprights are set into bases of heavy hard-wood two inches thick, ten inches wide, and three and a half feet long. Square holes are cut in the middle of these bases, two feet apart, so that eight inches of wood will extend beyond the holes at each end, and so provide a surface on which to screw the bracket-ends that act as braces to the uprights. The holes should be cut with a brace-and-bit all the way through the bases, and then trimmed with a mortise-chisel and mallet, taking care to make them very accurate, and so prevent any play to the uprights when once set up.
The stepping-plank is also of hard-wood, twelve inches wide, one and a half inches in thickness, and long enough to span the cross-planks. The distance between uprights should be about four feet. The stepping-plank should have a two-inch block under the middle to prevent it from springing; it is to be attached securely to the cross-plates with large, flat screws driven into holes that have first been bored out with a bit. Hollows are cut out in the top of each upright with a compass-saw, and the sides slightly tapered to the edges of the U cuts, so as not to interfere with the hands when using the bars. Fasten the bars to the uprights with two slim screws at each side, driven through the uprights and into the under sides of the bars. Do not put a screw or nail down through the bars and into the top of the uprights, for this will weaken the bars, and if the weight is suddenly transferred to the extreme ends they might snap off.
At a hardware store purchase four iron brackets with eight-inch tops and ten or twelve inch sides. Invert them and screw the tops to the base-boards and the sides to the outer edges of the uprights, to insure added rigidity.
A coat or two of paint will improve the appearance of the uprights and base; but do not coat the bars with anything. They should be polished with an oiled rag until smooth enough for use.
A Floor Horizontal Bar
The complete apparatus is shown in Fig. 13. The hickory bar, one and three-quarter inches in diameter and four feet long, is supported on hard-wood uprights two inches thick, three inches wide, and as high as the bar is desired—say from five to six feet, according to the stature of the boys who are to use it. At the lower end the uprights are held in position by two half-inch iron pins driven into the bottom. These fit into holes made in the floor in a corresponding position, as shown at A in Fig. 14. The upper ends of the uprights are cut with a compass-saw to receive the bar, and the edges are tapered to meet the edges of the U cut, as shown at B in Fig. 14. When the bar is in place it is held with straps made of one-eighth by one inch iron. They should be provided with screw-holes, as shown at C in Fig. 14. The ear-plate attached to each upright under the bar (and to which the stanchion wires are fastened) is made of one-inch tire-iron a quarter of an inch thick; it is bolted to the wood as shown at D in Fig. 14. A blacksmith will make the strap and ear-plates for a small sum; and at a hardware store staple or eye plates may be purchased and screwed to the floor, into which the turn-buckles can be caught.