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7-12 Adjustment of the thread trimmer
7-12-1 Structure of the thread trimmer mechanism
The thread trimmer mechanism of sewing machine is shown on the figure.
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<2>
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<1>: Knife mounting unit <2>: Knife bracket <3>: Trimming cam <4>: Air cylinder <5>: Stopper
<6>: Cam follower crank 2 <7>: Cam follower crank 1 <8>:Knife driving shaft <9>:Driving crank
<10>: Movable knife <11>: Stationary knife <12>: Thread guide
★A lower shaft cam method is incorporated for the thread trimmer mechanism. When adjusting the
sewing machine, if the thread trimmer air cylinder is in the operable state (state in which the cam
follower crank 2 arm is engaged with the thread trimmer cam) and the upper shaft is rotated, the
movable knife will collide with the needle and cause damage.
For avoiding this incident, always activate the air cylinder only in the regular trimming cycle which the
needle moves from its lower to upper position.
7-12-2 Assembling and readjustment of the thread trimmer mechanism
If take the trimmer mechanism apart and assemble it again, please refer to the following instructions
for the readjustment. For adjusting the trimmer mechanism, it is necessary to remove the sliding
plate.
7-12-2.1 Attaching the knife bracket and the knife mounting unit
(1) Knife bracket
Under the condition that the rotating hook and the hook positioner are removed, put the knife bracket
(No.1) on the lower shaft left bushing (No.2) and fix it with the two set screws (No.3).
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CAUTION
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