fio. 121. console j'anotubular aluminum bakelite and plywood .
fig. 122. high stools of leather and nickel. welded joints .
AA Quality, A Quality, Number 1 Quality, Number 2 Quality, Number 3 Quality. Without entering into details of each quality, it may be said that the AA grade must be entirely free from major defects; only well-distributed, fine seed and small, fine hairlines when not grouped are permitted. Number 2 grade, for example, may contain the following defects: numerous scattered seed, occasional coarse seed, light reams, strings, light scratches, short finish if not torn, hairlines if not too densely grouped, and bulls' eyes if not visible from front inspection.
These classifications will give an approximate idea of the wide variation of permissible defects and will be of service to the purchaser. Window glass is considered too thin for furniture construction; but there is less expensive plate glass appearing on the market, although at present its maximum thickness is 9/64 of an inch.
While this book is not planned to describe constructive processes, nevertheless occasional suggestions may prove valuable. Figures 115, 116, and 117, Plate 15, emphasize the bending of metal tubing. First the tube is filled with wet sand, the ends plugged, and the filled tube placed in the position indicated in any one of the three figures referred to, engaging the channeled jig forms. These pulley-like forms are quickly turned on the lathe out of hard wood and are valuable for simple bends. Figure 117 suggests an elliptical form, producing elliptical bends of greater beauty and dynamic force than the arcs of Figures 115 and 116.
Aluminum, stainless steel, or monel metal tubing similar to the material used in Figure 121 is cut for corners as shown in Figure 118, while the tubing is held in place as indicated in Figure 119. Wooden plugs driven into the tubing are used in holding secure the T joint of Figure 120. The growing use of masonite and plywoods for construction make for
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THIS book is one of the series of Handbooks on industrial subjects being published by the Popular Mechanics Company. Like Popular Mechanics Magazine, and like the other books in this series, it is written so you can understand it. The purpose of Popular Mechanics Handbooks is to supply a growing demand for high-class, up-to-date and accurate text-books, suitable for home study as well as for class use, on all mechanical subjects. The textand illustrations, in each instance, have been prepared expressly for this series by well known experts, and revised by the editor of Popular Mechanics.