https://mechcalc.net/blog/en/tags/thread-classification/ Recent content in Thread Classification on MechCalc how-to Guide https://mechcalc.net/blog/og-default.png https://mechcalc.net/blog/og-default.png Hugo en Sun, 22 Mar 2026 22:58:00 +0100 https://mechcalc.net/blog/en/posts/bolt-basics-01-thread-geometry/ Sun, 22 Mar 2026 22:58:00 +0100 https://mechcalc.net/blog/en/posts/bolt-basics-01-thread-geometry/ The bolted joint is one of the most widely used connection methods in mechanical engineering. Starting from the inclined-plane nature of a thread, this article sets out thread geometry and classification: the lead angle, the pitch, the pitch diameter d2, the minor diameter d3 and other key geometry parameters; common thread profiles and technical standards such as metric ISO coarse/fine, pipe threads and trapezoidal threads; and the functional distinction between fastening bolts, motion screws and sealing/adjusting bolts — laying the geometric groundwork for the later bolt strength calculation and pre-selection.