Parallel bars hold a high place in the affection of those who frequent gymnasiums as the best apparatus for development of the back and shoulder muscles, as well as a promoter of ease and grace of movement. The outdoor “gym” can have a set of these bars with very little more labor than was required for the horizontal bar.
Excerpt from the book: THE BOY MECHANIC VOLUME I – 700 THINGS FOR BOYS TO DO WITH 800 ILLUSTRATIONS 1913, BY H. H. WINDSOR CHICAGO POPULAR MECHANICS CO. PUBLISHERS
The material required is as follows:
4 posts, preferably cedar, 4 in. square and 6 ft. long; 2 base pieces, 4 in. square and 5-1/2 ft. long; 2 cross braces, 2 by 4 in. by 2 ft. 2 in. long; 2 side braces, 2 by 4 in. by 7 ft. 8 in. long; 4 knee braces, 2 by 4 in. by 3 ft. 8 in. long; 2 bars of straight grained hickory, 2 by 3 in. by 10 ft. long; 4 wood screws, 6 in. long; 4 bolts, 8 in. long; 8 bolts, 7 in. long and 1 doz. large spikes.
To make the apparatus, lay off the bases as shown in the end view and bevel the ends at an angle of 60 deg. Chisel out two notches 4 in. wide and 1 in. deep, beginning at a point 9 in. from either side of the center. These are to receive the lower ends of the posts. Bevel two sides of one end of each post down to the width of the finished bar—a little less than 2 in.
Cut notches in these ends to receive the oval bars. Bevel the ends of the knee braces, as shown in the diagram, and fasten the lower ends to the beveled ends of the bases with the spikes. Fasten the upper ends of the knee braces to the uprights with the 8-in. bolts put through the holes bored for that purpose and countersinking the heads. Lay the whole end flat on the ground and make a mark 2-1/2 ft. from the bottom of the base up along the posts, and fasten the end braces with their top edges flush with the marks, using four of the 7-in bolts.
Finally, toe-nail the base into the ends of the posts merely to hold them in position while the whole structure is being handled.
Two endpieces must be made. These sets or ends of the apparatus are to be buried in trenches dug to the depth of 2-1/2 ft., with the distance between the two inner surfaces of the posts, which face each other, of 7 ft. After the trenches are dug, additional long, shallow trenches must be made connecting the posts to receive the side braces. The function of these side braces is to hold both ends together solidly. It is necessary to bury these braces so they will be out of the way of the performer.
The side braces are bolted to the posts just below the cross braces, so the bolts in both will not meet. The bars are dressed down so that a cross-section is oval as shown in the end view. They are to be screwed to the notched ends of the uprights with the 6-in. screws.
The holes should be countersunk so they can be filled with putty after the screws are in place. The bars should be well oiled with linseed oil to protect them from the weather, and in the winter they should be removed and stored.
Every piece of wood in this apparatus can be round and cut from trees, except the bars. If using mill-cut lumber, leave it undressed, and if using round timber leave the bark upon it as a protection from the weather. It is well to paint the entire apparatus, save the bars, before burying the lower part of the end pieces.
The wood so treated will last for years, but even unpainted they are very durable. Be sure to tamp down the earth well about the posts. A smooth piece of ground should be selected on which to erect the apparatus.