(57) The invention relates to a buttonholing machine (10). The buttonholing machine (10)
includes a needle bar turning base which is arranged inside an arm portion (2c) of
a frame (2), and a looper base (47) and a turning mechanism (60) which are arranged
inside a bed portion (2a). The turning mechanism (60) includes a turning motor (61)
which serves as a turning drive source, a driving pulley (62) coupled to the turning
motor (61), a first driven pulley (63) coupled to the looper base (47), a transmission
shaft (64) which transmits a rotational force to the needle bar turning base inside
the arm portion (2c) from the inside of the bed portion (2a), a second driven pulley
(65) coupled to the transmission shaft (64), and a timing belt (66) which transmits
the rotational force from the driving pulley (62) to each of the first and second
driven pulleys (63, 65). A rotation ratio of two of the driving pulley (62), the first
driven pulley (63), and the second driven pulley (65) is other than 1:1. An origin
detecting means (68, 69) for detecting an origin position of the turning motor (61)
is provided on each of said two pulleys.
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