A Manual of Engineering Drawing; For Students and Draftsmen

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1911 Excerpt: ...up of more than one plane, particular care must be exercised in preserving the relationship by selecting one as the starting plane and working from it. In such a figure as the link, Fig. 255, the front bosses may be imagined as cut off on the plane A-A, and the front view, i.e., the section on A-A drawn as the front of the oblique projection. On axes through the centers C and D the distances CE behind and CF in front may be laid off. When an object has no face perpendicular to its Fig. 257.--Piping system in oblique drawing. base it may be drawn in a similar way by cutting a right section and measuring offsets from it as in Fig. 256. This offset method, previously illustrated in the isometric drawings, Figs. 239 and 240, will be found to be a most rapid and convenient way for drawing almost any figure, and it should be studied carefully. Fig. 257 is an illustration of a piping lay-out, showing the value of oblique drawing in explaining clearly what would be very difficult to represent in orthographic. Circles in oblique drawing may either be plotted, or may be drawn approximately, on the same principle as Fig. 241, by erecting perpendiculars at the middle points of the containing square. In isometric it happens that one intersection falls in the corner of the square, and advantage is taken of the fact. In oblique its position depends on the angle of the cross axis. Fig. 258 shows three oblique squares at different angles and their inscribed circles. Cabinet drawing is a modification of oblique projection in which all the measurements parallel to the cross axis are reduced one-half, in an attempt to overcome the appearance of excessive thickness produced in oblique drawing. The cabinet drawing Fig. 259 may be compared with the oblique drawing Fig. 255. Axono...