Differential feed is when the upper and lower layers of the material are fed at different speeds, or as in overlockers when the front and rear of the feed dogs are moving at different speeds. The result is that the sewing gets stretched or gathered, either all of it or just one layer relative to the other. Anything to make ruffles. 🙂
Differential feed in your overlocker
Let’s start with the overlocker as this is actually more straightforward.
Many overlockers have differential feed which can stretch or gather your sewing. It was originally developed in an attempt to even out the sewing, not to deliberately stretch or gather it. It will still do that, it all depends on the fabric.
The feed dogs are divided into two individually driven parts: front and back.
When the front feed dog moves faster than the back one, the material gathers under the foot, so the sewing gathers. This is the same as trying to manually stuff extra material under the foot as you sew.
When the front feed dog moves slower than the back one, the material is pulled back, so the sewing stretches. This is equivalent to manually pulling or stretching the material as it goes under the foot.
Here is a flounce that I made using differential feed.
The rolled hems are done with a bit of a stretch to give them a flare. The top is sewn with maximum gathering (factor 2.0), and as you can see, this is not spectacularly full. So it needed further gathering when attaching to the skirt.
The gathering foot
This foot is meant for gathering up one layer of the material while attaching it to the other. This foot exists both for sewing machines and for (some lucky) overlockers. It has a characteristic slot underneath for separating the two layers.
The bottom layer that touches the feed dogs, gets gathered while the top layer is pulled through.
This works well if the top layer that goes into the slot, is non-stretch. Otherwise instead of being pulled through, it is being stretched out and the machine chokes on more and more gathers that are being fed under the foot but not pulled out.
To regulate the fullness of gathers, you change the stitch length: shorter stitches usually result in fuller gathers (depends on the material). On an overlocker you can also add the differential feed.
The overlocker foot puts the ruffled and the plain material in one seam that is also immediately overcast. Best use the 4-thread overlock stitch here.
The sewing machine foot also allows to stagger the two layers. You could also have your ruffle lie to the right of the needle and the main piece to the left, attaching the ruffle to a finished edge from below. This makes a very neat stitch.
But I want to attach my ruffle to jersey, and that doesn’t work very well with either of those feet. Actually, both machines choked because the top layer was so stretchy.
Ok then, bring out the big guns. And I mean BIG!
The ruffler works in the opposite manner to the gathering foot: it gathers the top layer and attaches it to the flat bottom layer, with or without extra lace, facing and/or piping, with gathering, ruffling or pleating, constantly, in groups or not at all, while expertly performing Ravel’s Bolero on the piano. Anything to make ruffles. 😉
But I just want to sew my flounce to the hem, staggering the edges. So, I insert the flounce between the blades and the skirt underneath it all. It will be moved by the feed dogs, so it doesn’t matter that it’s jersey – this is like regular sewing.
The fullness of gathers is regulated by a screw (C) on the ruffler and no longer depends on the stitch length. Sort of. The gathers can be done on each stitch, every 6 or 12 stitches, or not at all (use contraption D-E).
This is absolutely brilliant! Behold the finished flounce.