Industrial Arts Design / A Textbook of Practical Methods for Students, Teachers, and Craftsmen

by William H. Varnum

Plate 17

Requirements for Appendage Design
Freehand Curves

It is the unexpected curve that is welcome in all designing, provided it supports the structure and conforms to established rules. After completing a design involving appendages it should be checked from three points of view; (1) service, (2) unity between the primary mass and the appendages, and (3) variety of curvature. On this last point it is needless to say that compass curves are not desirable except in rounding small corners or in using fillets. It is well known that compass curves are difficult to assimilate into pleasing tangential effects. They are inclined to be monotonous and regular with a "made by the thousand" appearance to them. One should trust to freehand sweeps, drawn freely with a full arm movement when possible. All curves should spring naturally from the primary mass. Blackboard drawing is excellent practice for the muscles used in this type of designing. In a short time it will be found possible to produce the useful long, rather flat curve with its sudden turn (the curve of force) that will make the compass curve tame and commonplace by comparison.

Appendages in Metal

[Figures 55], [56], and [57], [Plate 18], show the close bond between the appearance of the appendage in clay, and the one in metal. While it is technically more difficult to adapt metal to the rules governing appendages than is the case with clay, the final results are, in most instances, equally pleasing to the eye.

In most of the figures showing examples in metal, the appendages have to be secured to the primary mass by screws, rivets, or solder, whereas in clay they may be moulded into the primary mass. This tends to secure a more unified appearance; but in metal, the junction of the handle and the primary mass is often made a decorative feature of the design and gives added interest and variety to the project.

The simple primary mass, [Figure 58], has a horizontal space division in the lower portion of the mass. This point of variation of the contour has been used in the primary masses in [Figures 55], [56], and [57], also as the starting point of that dominant appendage, the handle. Springing tangentially from the body, it rises in a straight line of extreme value in service, then with a slight turn it parallels and joins the top of the bowl, thus fulfilling the design functions of an appendage from both points of service and beauty. The spout and lid, [Figure 55], may be likewise analyzed.