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20. Setting of the needle bar and of the hook shaft position (Fig. 20, 21)
Caution! Danger of injury!
Switch off the main switch! Before starting the setting operation, wait until the motor stops!
After a larger repair of the machine it is suitable to check up the mutual position of the needle bar in its central position and that
of the hook shaft. The axis of the hook shaft is shifted to the left from the axis of the needle bar. Proceed to the respective setting
after having loosened two screws (3), which secure the clamping joint between the bedplate and the hook gearbox. In its correct
position, the hook gearbox is pushed to the riser of the bed plate and the axis of the hook shaft is parallel with the plane of the
bedplate. Secure the box position in tightening both screws (3).
Notice!
In case of dismounting the hook gearbox it is necessary to respect, when remounting it, the parallelism of the axis of the hook
shaft with the plane of the bed plate. This parallelism is measured e.g. by means of two shafts, which we place on the top surface
of the bedplate and on the machined surface of the gearbox. We check up this parallelism in measuring the value (B).
21. Time setting of the control cam of the thread cutter
(Fig. 22)
Caution! Danger of injury!
Switch off the main switch! Before starting the setting
operation, wait until the motor stops!
For a safe and correct thread catching under the throat plate it is
neces-sary to set the correct position of the control cam which is
placed on the bottom shaft. From this cam, the movement of the
thread wiper derived for catching the upper and bottom thread
including its cutting, and the mechanisme of the tensioner. With
the machine switched off, tilt the machine head and, using the
hand wheel, set the take-up lever into its top position. Loosen
two screws (1) of the cam (2) and set the loosened cam in such a
way, so that we set the gauge mark on the cam (marked with
colour) into the axis of the pin (3) and secure the cam anew by the
screws (1). This position is to be taken as a basic setting of the
cam and it is necessary to eventually reset it according to the
thread or sewn material type. The start of the thread wiper
movement is to be set in slight turning of the cam on the bottom shaft. Push the lever (4), in this way the pin (3) is put into the
straight course of the groove. In turning the hand wheel in the direction towards the sewer (in counter-clockwise direction) check
the start of the movement of the thread wiper from the starting into the rear position.
Check the correct position of the thread wiper as follows:
At the moment when the loop of the upper thread and the bottom thread will leave the knocking-over slide of the hook and form
so a characteristic triangle, the point of the thread wiper should be in its close vicinity. When further turning the hand wheel, the
point of the thread wiper must pass through the triangle (one branch of the upper thread loop, bottom thread on one side of the
thread wiper and the other upper thread loop branch on the other side of the thread wiper). The thread lying on the side of the
wiper provided with a cutout, must fit into this cutout.
After having loosened two screws (1) on the cam (2) set the start of the thread wiper movement. In turning the cam in the direction
of the bottom shaft rotation the start of the thread wiper is accelerated and, inversely, it is delayed. After having set up the cam,
check whether the pin (3), after pushing on the lever (4), fits easily onto the straight part of the cam (2) groove. Push the carrier
ring (5) to the cam set up in this way and tighten it up with the screws (6) on the bottom shaft.
Fig. 20
6
5
8
9
8
1
2
3
3
Fig. 21
7
12
13
11
10
4
Fig. 22
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