#assembly

Worst-case against root-sum-square, when each one is honest, how to build a stack loop that does not lie, and why a design that only works on paper fails on the line.

How the ISO 286 system of shaft and hole letters and IT grades produces clearance, transition and interference fits, what H7/g6 and H7/p6 actually mean on the bench, and how to choose one.

What a bolt actually does, how property classes 8.8, 10.9 and 12.9 are defined, why most of the torque you apply never reaches the joint, and why angle and yield control exist at all.

Why bolts come loose, the difference between losing preload and actually unwinding, what the Junker test proved about spring washers, and which locking methods work for which mechanism.

Interference fits and how much torque they really carry, shrink and cryogenic fitting, why splines beat keyways for reversing loads, and what a circlip is and is not allowed to do.

Why weld shrinkage moves a part in three different ways, how a fixture locates rather than forces, why sheet metal needs N-2-1 instead of 3-2-1, and how weld sequence is used to make distortions cancel.

Reference point systems and master locating points, why the same holes must be used from press shop to final assembly, and how functional build differs from building every part to nominal.

Poka-yoke that prevents rather than detects, why a torque tool that only beeps is not error proofing, what broaching and part marking are for, and how traceability turns a recall into a contained one.