What is thread size and why does it matter?

Bolts and, their often, associated nuts are a staple in modern engineering. Yet there seem to be lasting misunderstandings about describing bolts and their characteristics!
This article aims to clarify the different annotations used to describe metric bolts.

Metric bolts follow a standard way of describing their sizing, this is done in the following format:

We can dissect the formulation of metric bolt notation like follows:

- The letter "M" stands for the fact that this bolt is notated in the metric form.

- The number directly behind the "M", indicates the width or diameter of the bolt in millimeters.

- The number 1.5 refers to the pitch of the bolt. Pitch means the distance between threads in millimeters.

- The number 30 is the total length of the bolt in millimeters.


© 2022 Thomas Schenk