TABLE OF CONTENTS There are hundreds of applications for threads. One of the most common uses is machine bolts and other threaded fasteners. Threads are also used in applications to adjust, clamp, control, measure, and move various items. Threads are generally made of steel, but can be made of other metals and plastics. Some machine components have threads as an integral part of their design; spark plus and oil filters are examples of parts with built-in threads.
Threads are used in many different forms, such as screws, bolts, studs, nuts, and inserts. Threads are generally made to industry standards and also to special requirements. Although there are many different types of threads, most of the terms that are used are universal. The purpose of this chapter is to review the terms that are normally used with threads. The way threads are shown and identified on prints will be examine. Four popular threads will be described: Unified, metric, Acme, and pipe. Other types will be similar. Additional data on these threads and information on other types of threads are shown in Machinery's Handbook.
Threads may be shown on prints in three different ways; they may be shown in graphic, schematic, or simplified form (Fig. 8-1). The graphic method shows threads as they actually appear; the schematic method resembles threads to some degree; and the simplified method uses solid and dashes lines to represent threads. The simplified form is the one generally used on industrial prints. Sometimes more than...
