|KEY WORD : architecture / tools|
|A gimlet. A tool used to bore holes in timber by rotating the blade tip. Gimlets are divided into three types depending on the structure of the cutting tip and the way it is rotated. One type is the momigiri 揉錐 which is repeatedly rotated backwards and forwards. The other two types, the bourutogiri ボールト錐 and the kurikogiri 繰子錐, are rotated in one direction only. To bore holes the momigiri handle is gripped between the palms of the hands and rotated alternately left to right and the reverse. The handle is made from Japanese cypress hinoki 桧, or Japanese white pine himekomatsu 姫小松. The handle is about 240-360cm long and the diameter at the mouth nearest the blade motokuchi 元口, is approximately 15-21mm. The momigiri is given different names depending on the form of the cutting tip, for example the three pronged gimlet is called mitsumegiri 三目錐, the four pronged gimlet yotsumegiri 四目錐 and the rat's tooth gimlet nezumibagiri 鼠歯錐. The bourutogiri works on the same principle as a screw. Wood shavings are ejected from the hole by a diagonal cutting blade like the spiral ridge of a screw. The screw-shaped heads of the cutting blade are fitted into the handle to form a T-shape. The hole is bored by gripping the handle with both hands and rotating the cutting tip. The third type of gimlet, called kurikogiri 繰子錐 (also called a brace), consists of a sharp head, inserted in a chuck at the tip of a U-shaped iron rod. A regulating screw permits different types of cutting heads to be fitted into the chuck, depending on the size required. The round handle at the other end is held steady, and the middle of the handle is rotated. The kurikogiri is a relatively powerful tool, suitable for boring large holes. All these gimlets have been displaced by the spread of the electric drill.|
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