The whole apparatus can be simply oiled thoroughly, or can be given in addition one or more coats of shellac or varnish (see Finishing), but a coat of oil is sufficient for the bars themselves, as they will be polished by use.
This arrangement has the advantage of being portable, but of course the base can be omitted, if desired, and the posts fastened directly to the floor. If mortises cannot be cut in the floor, blocks can be screwed to the floor around the base of each post so as to form a socket into which the post will fit.
Parallel bars can be readily made for outdoor use by simply setting four upright posts (not less than 3" × 4") firmly in the ground, at the same distances apart as specified for the movable bars described above, and fastening the bars to the tops of the posts by mortise and tenon, as already shown (Fig. 263). The posts should reach 3' or more below ground, both on account of the frost and to give increased steadiness, and the earth should be thoroughly tamped down around them with a sharp-pointed bar or stick. This apparatus should be thoroughly oiled and can be varnished (see Finishing). The posts should be of good thickness at the ground, but can be tapered toward the top, on the outside, to the thickness of the bars.
Horizontal Bar.—A design suitable for the amateur wood-worker is shown in Fig. 265.
Before beginning work read carefully Marking, Rule, Square, Saw, Plane, in [Part V]., and look up any other references.
First make the upright posts or guides. These are somewhat like a trough in shape, side boards about 6" wide being screwed (see Screws) on the sides of a 2" × 3" joist. Fig. 266 shows sections in the middle and at each end, blocks being inserted at the ends for strength. The joist can be of any strong wood. The side boards, which serve as guides for the bar, had best be of hard wood. Hard pine, oak, maple, ash, or any strong wood can be used. You will require two of the joists and four side boards, all sawed squarely off the exact height of the room.[23]
The usual way would be to get out the pieces a little too long and, after they are fastened together, to saw off the ends so as to give the required length. Gauge lines on each side of the upright pieces (see Gauge) and intersect these lines at regular distances by others squared across and around three sides of the uprights, thus determining the places for the holes for the pins which hold the bar in position. These can be bored from each side with a 3/8" bit (see Boring).
Fig. 265.