What does a thread's start indicate?

The start of a thread refers to the specific point at which the threading begins on a fastener, such as a screw or bolt. This is crucial for understanding thread design because it indicates how many threads are present and how they are configured along the length of the fastener. When a fastener has multiple starts, it means there are multiple helical threads that wrap around the cylinder simultaneously. This allows for increased engagement, enables faster assembly, and can influence the load-carrying capabilities of the fastener.

In contrast, total thread length, diameter of the cylinder, and depth of the thread are metrics that describe different aspects of a thread but do not directly pertain to its starting point or the configuration of the thread. Therefore, recognizing that a thread's start directly relates to the number of individual threads provides clarity on how the fastener functions in practice.