Guides

6 articles on choosing and specifying fasteners — the reasoning that a dimension table cannot carry.

Selection

2 articles
SelectionHow to choose a bolt property class8.8, 10.9 and 12.9 are not simply better-fastener versions of each other. This covers what the numbers mean, when the upgrade makes the joint worse, and how to match the nut.SelectionHow to read a fastener part numberA part number like DIN 912 M6x30-8.8-A2A carries five separate pieces of information. This breaks the string down so you can check a specification against what arrives.

Threads

2 articles
ThreadsThread pitch, coarse and fine — what actually changesCoarse and fine threads of the same diameter are not interchangeable, and the difference is not just the pitch number. Here is what changes in strength, sealing and tapping.ThreadsTap drill size and thread engagementGetting the tap drill right, and knowing how deep a thread must engage for the bolt to be the weak link rather than the thread.

Standards

1 article
StandardsDIN vs ISO: when equivalents are actually interchangeableA standard being listed as equivalent does not mean the parts can be swapped without checking. This shows where the differences hide and how to verify a substitution.

Materials

1 article
MaterialsA2 vs A4 stainless fasteners — and why the strength number misleadsA2-70 and A4-70 look like high-strength grades but are weaker than a plain 8.8 steel bolt. Here is what the stainless grades mean and how to choose between A2 and A4.

Reference data

All specificationsStandardsThreadsSizesMaterialsProperty classesComparisons