A compact reference guide for machining threaded holes is an essential tool for any machinist, particularly those working in smaller workshops. This guide typically provides information on tap sizes, drill bit sizes for corresponding threads, and recommended cutting speeds and lubricants. An example would be a laminated card displaying data for common thread standards like Unified National Fine (UNF) and Unified National Coarse (UNC). It might also include metric sizes and specialized threads like pipe threads.
Access to this concise information streamlines the workflow by eliminating the need to consult multiple resources, reducing errors, and saving valuable time. Having readily available data on appropriate drill sizes for different tap sizes is crucial for creating accurate threads and preventing tap breakage. Historically, machinists relied on extensive handbooks or memorized values, but these compact guides offer a more convenient and efficient solution. This efficiency becomes particularly critical in smaller shops where resources may be limited.
