(the jacaranda trees are blooming now, to me the most visually arresting sight in queensland is the fleeting patches of purple that show themselves this time of year. They glow valiantly, purple torches in the tired green treescape…. They’re in the header!)
Last week in the Tiramisu Circus, I bit off more than I could safely chew when I sat down to write about sergers/overlockers. No matter how I tried, I couldn’t fit everything I wanted to cover in one post, so I broke it up into a series of posts. This is the first of several “features” posts, to explore the functions of a serger/overlocker, discuss, and learn.
It’s up to you whether you want to use/shop for these features or not, I’m just here to chat about them!
Understanding and using differential feed helps create a quick, clean finish for any garment. (Not just knits! Adjusting differential feed can help tame difficult wovens, too!) It’s a feature of some overlockers/sergers, and has to do with the way the fabric feeds through the machine.
Note on names: Sergers and overlockers are different names for the same machines. In America (where I learned to sew), we use the word “serger.” In Australia (where I refined my skillz), we use the word “overlocker.” Sorry if that caused any confusion! What do you call this machine in your country/language?
Close Up Look
I have a Husqvarna 905, and she’s a workhorse. (It’s a shame they discontinued the line, 905 and 910 are great machines. Get one secondhand if you can.) I removed the foot to allow a clear view of the feed dogs. Many brands of overlockers feature “Differential Feed”- I think this is arguably the most useful feature of an overlocker.
Basically, “differential feed” means the machine has two sets of feed dogs- front and back. The machine can be set so they work together at the same speed, or so they work at different speeds. This allows for greater control and manipulation of the fabric.
What does Differential Feed Do?
I used the same temperamental knit jersey from The Circus’ trials to illustrate differential feed. In the top example, the differential feed was set lower than average. This means the front feed dogs feed in the fabric slower than it is fed out of the machine, basically it’s the equivalent of stretching the seam as you sew. In the second example, I left the differential feed at normal. For the final sample, I turned the differential feed up. I did not touch any other machine settings between samples.
Tip for sample sewing: adjust only one aspect of the stitching at a time, and do it gradually.
Here’s a close up- notice that the loops are a little “free.” This is because the low differential feed setting stretches the fabric and it shrinks away from the blade. If you want to create a rippled edge but also want tighter loops, you could try tightening the tension on the upper and lower loopers. A little at a time, with plenty of testing.
Unrelated Tip:You can use this to create fluted edges. Turn down the differential feed, gently tighten the looper tension and go for it. Try this also on the “rolled hem” setting for a lettuce-leaf hem.
When I sew with a new fabric, I usually test the various stitches I’ll use in the garment to be sure I like the settings. I always start at “normal” or default settings and tweak from there. This finish would normally be unacceptable to me, I’d know to turn up the differential feed to finish my seams.
Also, during the serging, I would see that the fabric cringes away from the blade. Some woven linens do this, too, and turning up the differential feed helps eliminate this problem.
This is my differential feed turned up higher than average. That means the fabric feeds in more quickly than it is let out; the back feed dogs “grip” the fabric so it slips and stretches less. In fact, it’s the opposite of stretching the fabric. LinB mentioned a manual equivalent of this when we were discussing prevention of rippled seams:
I hope this helps clear up “differential feed”! I wouldn’t be without it, and understanding the mechanics behind the feature absolutely leads to cleaner, neater sewing.
Do you ever use differential feed? What do you call this machine where you’re from? Do you have any tips for using differential feed to add to the discussion?
Up Next: Sourcing Eco-Knits
And then: Finished Object- Blue Seersucker Negroni
Next in the Serger Savvy Series: Presser Foot Pressure and Threading/Tension Options
By the way, I’m refraining from leaking Cake developments to the blog posts, all of that is now channeled into the Cake newsletter- sign up now so you don’t miss sneak peeks of the Tiramisu Dress instructions, as well as weekly sniplets about upcoming Cake releases. Later on, this is also where I’ll introduce “hacks” and “mods” of my patterns. I’ll also be hosting a few fun games and giveaways only open to Cake Updates subscribers. Don’t miss out! It’s been slow up to now, but we’ll be cooking with gas very shortly.