The Differential feed on an overlocker or serger is like a teamwork feature for the machine's front and rear feed dogs. It lets you adjust how these two sets of teeth work together.
The differential feed is a feature found specifically on overlockers / sergers and certain specialty sewing machines. So if you're new to overlocking / serging it may be a new concept for you.
The purpose of the differential feed is to control how the fabric is fed through the machine.
By adjusting the feed ratio between front and back, you can prevent issues such as stretching or gathering of the fabric, depending on the fabric type you are working on. You can also achieve specialist effects such as gathering.
A differential feed setting of 1:1 (neutral) means that both sets of feed dogs move at the same rate, while settings lower or higher than 1:1 cause the front and rear feed dogs to move at different speeds, resulting in stretching (1:2 or lower) or gathering (2:1 or higher) of the fabric.
A Differential Feed Setting of 1:1 (Neutral)
1:1 (Neutral): In this setting, both sets of feed dogs move at the same rate. It's suitable for most standard sewing tasks and woven fabrics where you want the fabric to be fed evenly without stretching or gathering.
A Differential Feed Setting of 1:2 (Stretching)
1:2 (Stretching): When you set the differential feed to 1:2 or lower, the front feed dogs move more slowly than the rear ones. This causes the fabric to stretch as it's fed through the machine. This is beneficial for knit fabrics and lightweight materials, preventing them from puckering or waving during sewing.
A Differential Feed Setting of 2:1 (Gathering)
2:1 (Gathering): Setting the differential feed to 2:1 or higher makes the front feed dogs move faster than the rear ones, resulting in the fabric gathering or bunching as it's sewn. This is useful for creating decorative gathers or ruffles in your sewing projects.