|I'm new to sergers so everything is a learning experience with my Huskylock 905. Lettuce edges seemed fairly easy but it still took awhile my first time. I learned that there are a couple different ways to achieve a lettuce edge, which is really just a rolled edge done on stretched fabric.
I used a mid-weight jersey knit, a stretch needle in the right position only, regular thread for the needle and wooly nylon in both loopers. I changed the tension guides for the loopers to D for decorative thread. It helps the wooly nylon feed better.
For both techniques, the stitch finger needs to be in the R position (it moves out of the way so the thread rolls directly onto the fabric). I used these settings:
Cutting width - normal
Stitch length - 1 mm
RN tension - normal
UL - 1 (if using wooly nylon, otherwise set at normal)
LL - 6
This is where the difference in techniques comes in and I tried them both. When not using differential feed, I stretched the fabric in front of and behind the presser foot while serging. When the tension on the fabric was released, the tightly stitched edge created a ripple.
Then I tried using differential feed by dropping it to the lowest level. Mine goes to .05. This way I didn't have to stretch the fabric, just guide it under the foot. The DF creates the ripple and, I believe, it's a much nicer look.
In the picture, the lower ripple was made by my stretching the fabric and appears to have sharper rolls. The upper ripple on the sleeve was made with DF and looks more wavy and flowing.
It's a fun and very easy way to finish an edge.