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Page:Popular Science Monthly Volume 90.djvu/481

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Popular Science Monthly

��465

��Making Parallel Bars for the Home Gymnasium

AS no gymnasium is complete without parallel bars, this plan of constructing them may- prove interesting. It is of simple construction, but as it is to be sub- jected to rough handling, every joint must be strong and rigid. Only the toughest wood will do. Ash is first choice, but maple, oak, elm, hickory, or any other straight-grained hard wood will do. Every piece must be carefully smoothed with sand- paper and rubbed with successive coats of oil. Begin - ning at the founda- tion, choose three planks that are flat and true, without warp or dip or curl. The dimensions are clearly shown in Fig. i. To get the curve at the ends of the shorter planks uniform, cut a paper pattern and use it for the four markings. Cut to the marks with a common handsaw, but the narrower the blade, the more con- venient it will be. A 6-in. groo\e is hollowed to the depth of J/2-in. in the sides

���Assembled parts mak ing the parallel bars for the gymnasium

��of the base pieces, as shown. This gives the base a better grip on the floor and makes a handhold for lifting.

The upright posts are next in order of construc- tion. They are 2^^ in. by 3 in. The joint used at the base of the post is shown in Fig. 2, and the mortise at the top in Fig. 3. Make the joints tight, and have the posts exactly vertical. The tools necessary are a brace and bit, wood chisel , saw, hammer and sandpaper. The four steel bar braces. Fig. 4, may be procured from a blacksmith. Wood braces may be used instead. Glue the bot- tom of the post and the sides of the socket it fits into, and drive- a couple of finishing nails rough it into the center plank. The dimen- sions of the top tenon are shown in Fig. 5 and Fig. 6. It is a cross-section of bar and shows form, thickness and width. If nails are used to reinforce the glue joint, sink the heads well below the surface. A thorough smoothing and rubbing with oil will complete the job.

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���FIG I

��Owing to the rough handling of parallel bars it is necessary to have the parts made of tough wood that is straight grained and put together with mortise and tenon joints and well oraced

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