differential feed

Differential feed is a mechanism on sergers and some sewing machines that uses two separate sets of feed dogs moving at different speeds to control how fabric is guided under the presser foot.

By adjusting the ratio between front and back feed dogs, sewers can prevent stretching on knit fabrics or create intentional gathering and lettuce edges.

I set my differential feed to 2.0 for the stretchy jersey so it wouldn't wave at the seams.

The feature is essential for professional-looking results on difficult fabrics.