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Boring machine (carpentry)
A carpenters boring machine is a hand driven machine to bore holes in beams such in the process of making a mortise or making holes for the wooden pegs which hold mortise and tenon joints together.
==History==
Before boring machines were invented carpenters used hand powered augers to bore holes. Most common were T-handled augers. The shape of the drill bits changed over time with the spoon bit and shell bit being common before the invention of the spiral or twist bit in 1771〔Joseph Hutchins, “The American Screw Auger” ''The Chronicle'' 64 no. 3 2011:89-107〕 which removes the cuttings as it turns. The exact origin of this invention is not known but the earliest patent is in the United States in 1830 by J. Beckwith and was as tall as a man and operated by a large wheel from the side.〔Greg Burket. ''Joiners Quarterly'' #17 (1991)〕
Boring machines use twist auger bits usually ranging in size from 7/8" to 2". The machines hold the bit perpendicular (square) to the face of the timber and are operated with both hands while the operator sits on the base to keep the machine from moving. Some machines can be set at an angle.
American manufacturers included “…Boss, Ajax, Snell Manufacturing Co., Sweet, Jennings, Saunders, R. Ball & co., Roswell Buck, Phillips, Millers Falls, Riley Smith, James Oppenheimer, and the Square Hole Auger Company. Some companies made 10 or 12 different models…”. 〔''Timber Framing'' #22 December 1991. 12.〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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