Differential Feed
Differential feed on an overlock is a two-part feed dog
which feeds the fabric at different ratios. The front part
of the feed dog feeds more or less fabric under the foot
than the rear part of the feed dog does. This feature is
useful when sewing knits which have a tendency to
stretch and result in waves when sewn on an overlock
machine. Differential feed is also good on sheer fabrics
which tend to pucker when sewn. Use the 0.5 setting
for eliminating puckers. There are two kinds of
differential feed: negative and positive.
Standard Feeding
The front and rear feed dogs work as a single unit. The
fabric feeds in and out with the same ratio.
Positive Feeding
The looser and stretcher the fabric, the more the front
part of the feed dog must feed in and the less the rear
part of the feed dog must feed out. Waves are
eliminated.
Negative Feeding
The front part of the feed dog feeds in less fabric than
the rear part feeds out. The fabric is held taut by the
feed dogs. Puckering is eliminated.
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