Joggling and flaring

In a busway housing the three or four phase bars are stacked, so their joint faces do not naturally lie in a common plane. A joggle is the offset bend that brings them into one — a short, controlled step formed at the joint end of each bar. Flaring then opens the joint end to accept the joint block. Both operations are repeated at every joint along a run, which is why they are worth automating: the tolerance that matters is not the accuracy of any single joggle but the accumulated pitch error across a six-metre housing and then across a run of them. Fish plates, the joint plates that clamp two sections together, are punched, stretched and sheared in a fixed sequence at better than ±0.1 mm/m for the same reason.