Pingbanfang Dajiao (平板枋十字刻半搭交): How the Bracket-Set Plates Cross at a Corner

The plate

The plate (平板枋) sits on the outer tie-beams and carries the bracket sets. Ma Bingjian gives its section as 2 by 3 doukou (the bracket module): 2 high, 3 wide.

Cross-halving

Where the plates meet at a corner, each is cut away by half its height at the crossing. The plate on the front of the building is cut on top, and the plate on the side is cut underneath and laid over it: the side elevation sits on the front. Outside each cut a lip is left, one tenth of the plate’s width deep, so the joint closes neatly on the face.

Pins

Hidden pins join the underside of the plate to the tie-beam, two to four in each bay, and the top is drilled for the pins that hold the cap blocks of the bracket sets.

A rule from the Qing manuals

Where two lengths of plate meet end to end over a column, the Yingzao suanli (營造算例) joins them with a dovetail key (銀錠扣) at each end, half the plate’s own width long, and only a quarter of the width reaches past the column centre line.

Proportions in the model are illustrative.