What is Differential Feed?

Have you ever experienced sewing with knits only to find your seam longer and wavier than before? Don’t worry, you’re not alone in this. Fortunately, most overlockers come equipped with a feature called differential feed, which can help you achieve the perfect seam finish. Not only does it rectify stretched-out seams in knit fabrics, but it can also be used to create gathers and scalloped lettuce edge finishes. Once you grasp the basics of how it works, you’ll find endless possibilities for employing it in your next project.

Understanding Differential Feed

Differential feed is often mistaken for dual feed or presser foot pressure. However, it is neither of these. When adjusting the Differential Feed knob on your machine, you are actually modifying the rate at which the front feed dog moves, while the back feed dog maintains a consistent rotation. This concept is illustrated in a schematic drawing found in the overlocker manual.

By setting the Differential Feed to 2, the front feed dog rotates at roughly twice the distance of the back feed dog, resulting in a greater fabric movement. This eliminates the stretched-out wave that occurs when sewing most knit fabrics. Conversely, when the Differential Feed knob is set to 0.7, the front feed dog makes a smaller rotation than the back feed dog, causing the fabric to stretch as it is sewn. Additionally, the Differential Feed is variable and adjustable, allowing you to fine-tune it while sewing, which is particularly useful for working with bias edges and inset sleeves.

Choosing the Right Setting

Determining the appropriate Differential Feed setting depends primarily on the fabric you’re working with. Woven fabrics generally achieve a flat seam along non-bias cut edges when set to 1. On the other hand, knit fabrics often stretch and create a wavy edge seam when set to 1. In this case, adjusting the Differential Feed setting towards 1.5 can help produce a flat and even seam.

If you’re looking to create ruffles, setting the Differential Feed to 2 is highly effective. The front feed dog pushes more fabric through at almost twice the rate, resulting in beautiful gathers. Pair this technique with a rolled hem edge finish for ruffles on items like pillows, bags, and children’s clothing.

For a scalloped lettuce edge finish or to eliminate unwanted puckering, adjust the Differential Feed to 0.7 while using a rolled hem. This setting works particularly well with stretchy spandex knits, enhancing the lettuce edge effect.

Conclusion

Understanding the uses of Differential Feed and how to apply it to your projects is crucial for achieving expert finishes. The overlocker is a powerful tool that can make a significant difference in the outcome of your sewing projects. So, embrace the Differential Feed feature and let it work its magic. Happy serging!