Design Nomenclature / Form & Geometry
Radius break
Also called break line, tangent line, the break, tangency line
This entry has not been translated yet and is shown in English.
The line where a fillet stops and the flatter surface it blends into begins — the tangent boundary of the round. A highlight terminates there, so the break's shape is read directly on the finished part: a wobbling break line reads as a wobbling form even when both surfaces either side of it are individually perfect.
In practice
'The break' or 'the tangent line.' A variable-radius fillet has one on each side and they rarely stay parallel; Class-A review is largely an argument about them. On a large radius it is the break, not the radius, that carries the shape.