isukatsugi いすか継

A halved rabbeted (oblique) scarf joint *sogitsugi 殺継. A simple scarf joint, often called a crossbill scarf because it resembles the open bill of a bird. The so-called 'female end' is spliced obliquely with half the width of the timber cut off from the top and the other half cut off on the underside. The 'male piece' is cut into exactly the same shape except that the oblique surfaces are reversed to allow them to fit together perfectly. Because this is a rather weak joint, a key *shachi 車知 is inserted into the double-faced joint a little over half the thickness of the timber. It does not reach through the lower face. Stub tenons are cut in proportion to the width of the joint. Called the sumikiri isukatsugi 隅切いすか継, it is used in buildings like monks' dormitories where appearance is unimportant. Also used to join the ribs *gōbuchi 格縁 of a coffered ceiling, *gōtenjō 格天井. More complex scarf joints include the one called the Miyajimatsugi 宮島継 which is a triple-faced, halved, rabbeted, oblique scarf joint with a key. It differs from ordinary triple spiced scarf joints in that it has a triple-faced cone shape at the end of the obliquely cut surfaces. One type of halved rabbeted oblique scarf joint has four faces. It looks simple but is very difficult to make. Isukatsugi joint and all its variations are made in the direction of the grain. Examples: Okadera 岡寺 (1612) in Nara, used on the eave purlin *dashigeta 出桁 of the gate, Niōmon 仁王門; Itsukushima Jinja Ōtorii 厳島神社大鳥居 (1875), in Miyajima 宮島, Hiroshima Prefecture. The Miyajimatsugi is used on this gate, from which it derives its name.