Square (carved ruler) - く

…(1) A metal ruler that also doubles as a right-angle ruler. In ancient China, a woodworking tool for drawing right angles was called a ku (square). It was made by bending a thin strip of metal at a right angle and marking the scale. It was also called a kane-zashi (square), a curved ruler, and written as kaku-shaku (square ruler) or tetsu-shaku (iron ruler). It consists of two branches, one long and one short, the long branch (nagate) being about 1 shaku 2 sun to 1 shaku 6 sun long and the short branch (tsumade) being about half that length. It is 5 bu wide and 2 to 3 rin thick. In the past, it was made of brass or steel, but nowadays it is made of stainless steel. …

*Some of the terminology explanations that mention "ku (curve scale)" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…(1)直角定規を兼ねた金属性のものさし。直角をだすための木工用の道具を古く中国では矩（く）といい，帯状の薄い金属板を直角に曲げた形に作ってあり，これに目盛をつけたものであり，かねざし，曲り尺ともいい，矩尺，鉄尺などとも書いた。長短2本の枝から成り，1尺2寸ないし1尺6寸程度の長さの長枝（ちようし）(長手（ながて）)とその半分程度の長さの短枝(妻手（つまで）)とから成り，幅は5分，厚さは2厘ないし3厘であり，古くは真鍮（しんちゆう）や鋼で，最近はステンレス鋼で作られる。…

※「矩（曲尺）」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報