Singer 321C - Adjusting the Differential Feed Rate; Stitch Length Adjustment

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High Speed Overlock Machine | Instructions Manual and Parts List
3.7
Adjusting the
Differential
Feed Rate
Adjustmentofthedifferentialisthe
dragging proportion between the
mainfeeddoganddifferencialfeed
dog.Whenthemovementofmain
feed dog is less than that of the
differencialfeeddog,theclothwill
befrilledduringsewing.Otherwise,
theclothwillbestretched.
3.8
Stitch Length
Adjustment
The stitch length
adjustment is
made according to
the sewing fabric,
differential feed ratio
and other factors.
Important
Pressbuttontotheendandkeepit
pressedasshownongure15.
Turn the wheel until we have the
desiredstitchlength.Itisshownon
thewheelscale.
Figure 15
Figure 14
Releasenut‘1’ ongure14,andturn
screw‘2’ clockwisetostrechingthe
clothorcounterclockwisetoshrink
it.Retightendthenut‘1’.
Adjust
Differential
Scala
1 2 3 4 5
1 : 3 - 1 : 0.7 1 : 0.9 1 : 1.1 1 : 1.3
1 : 2 1 : 0.7 1 : 1.0 1 : 1.4 1 : 1.7 1 : 2.0
1 : 3 1 : 1.0 1 : 1.5 1 : 2.0 1 : 2.5 1 : 3.0
1 : 4 1 : 1.1 1 : 1.6 1 : 2.3 1 : 2.8 1 : 3.3
When the surface of
level ‘3’ adjustment
is on scale 2, the
differential adjustment
is 1 : 1, and if it is
on the scale, its
proportion may be
adjusted up to 1 : 0.7.
Note
Dragging
Proportion
Type of
Machine
Wheel Scale
1 2 3 4 5 6 7
1 : 2.0 Seaming 1.0 1.5 2.0 2.5 3.0 3.5 3.8
1 : 3.0 Shirring 0.7 1.0 1.4 1.7 2.0 2.3 2.5
1 : 1.3 Serging 1.6 2.3 3.1 3.9 4.7 5.4 5.9
1 : 4.0 Special 0.6 0.9 1.2 1.5 1.8 2.1 1.0