Chapter 8 Tube Parts - Alignment- The Finder

The Mirror Cell. The wooden cell described here is easily made and permits of ready adjustment. The materials required are: two well-seasoned hardwood boards, one 6" square and :¾" thick, and the other about 8" square and 1" thick; three WSO round-head stove bolts, 3" long, and nine washers to fit; three very stiff compression springs, ¼" to ½" long and large enough in diameter to fit freely over the stove bolts; three ¼-20 wing nuts; three 10-24 round-head machine screws %" long: three 10-21's 1" long. Clips for securing the mirror to the cell can be cut from brass angle shapes obtainable from the 5 & 10. On the small board inscribe an equilateral "triangle" in a (V circle as in Fig. 57a. Mark the holes for the stove bolts 2.1" from the center.

On the large board lay off the equilateral "triangle" inscribed in a circle of the same diameter as the inside of the tube (Fig. 57b). Drill center holes in each board, the size of a dowel stick or bit of rod that may be on hand, and saw out the triangles; the corners must be cut to exactly the proper radius and be made concentric.

Center the triangles on each other by passing the dowel stick or rod through the center holes, clam]) them, and drill out the stove-bolt holes with a ¼" drill. Before
separating the triangles, mark them so that they can be returned lo the same respective positions. Then enlarge the holes in triangle b with a 9/32" or 5/16" drill to permit free movement over the stove bolts. Drill holes in the angle clips with a No. 12 drill, and elongate them slightly with a small round file. The clips are
fastened to the corners of triangle a with the ⅝" screws, first drilling holes for them into the wood with a No. 24 drill. The machine screws will have ample holding power and are preferred to wood screws where frequent removal may be necessary.

Before placing the mirror in the assembled cell, file a small flat area on the heads of the stove bolls, and cement to them thin pieces of felt, cork, or leather, on which the mirror will rest. The small on the heads of the stove bolls, and cement to them thin pieces of felt, cork, or leather, on which the mirror will rest. The small dotted circles in the center of each triangle may be cut away with a scroll saw to give ventilation.

The Mirror Cell part2