Ever Tried This on Your Serger? This Differential Feed Feature Will Amaze You

In this article, we dive into the world of differential feed, an essential but frequently overlooked feature of sergers.

A serger stitches with two sets of feed dogs, those tiny toothed metal bars that peek out from the machine’s throat plate. These feed dogs move the fabric through the machine as you sew. They can be adjusted to move at different speeds, either stretching or compressing the fabric as it goes under the needle. Now, the differential feed is the maestro of these feed dogs, conducting their pace. When you adjust the differential feed, you’re telling one set to either take larger steps or smaller steps compared to the other.

Speed up the front feed dogs, and the fabric bunches up. Slow them down, and the fabric stretches out. It’s this simple tweak that lets you manage how the fabric behaves as it’s serged.

Why bother with this setting? Well, imagine you’re serging a seam on a stretchy fabric without adjusting the differential feed. You might end up with a wavy, distorted edge that screams “oops” instead of “perfection.” Or perhaps you’re working on a delicate chiffon that puckers as you sew. Differential feed is your tool to smooth out these issues.  And when you want to add a bit of flair with gathers, it’s your go-to tool for easy execution.

Attention! If you’re someone who likes to see things in action, you might enjoy the video version of this tutorial on my YouTube channel. You’ll find the link at the bottom of this post. Watching the video along with reading this article can help you get a fuller picture, so I definitely recommend checking out both!

Setting Up Your Serger for Differential Feed

Before you can become a differential feed master, you need to know where to find this feature on your serger and how to use it. 

✅Related tutorial: Serger vs. sewing machine

Guide to Locating the Differential Feed Setting

1. Make sure your serger is turned off. Safety first!  We’re dealing with moving parts here, and we want all our fingers intact by the end of this.
   
2. Look for a knob or lever. Take a peek at the side of your serger. You’re looking for a knob, dial, or lever that’s usually marked with numbers and sometimes the letters N, C, or D. Found that knob or lever? Great! It’s typically located near the right-hand side of the serger.

3. Check Your Manual. If you’re struggling to find the control, consult your serger’s manual.

Understanding the Settings

Here’s a breakdown of what happens when you adjust the differential feed setting:

Setting the Differential Feed to N (Neutral)

• When the differential feed is set to N (typically 1.0), both sets of feed dogs move at the same rate. This means the fabric is fed through the machine evenly, without being stretched or gathered.
• This setting is generally used for most standard serging tasks where no stretching or gathering is desired

✅Related tutorial: The Self-Threading Serger – Yes, It Exists!

Increasing the Differential Feed (Setting Above N)

• Turning the differential feed setting up from N (to a higher number up to 2) causes the front feed dogs to move faster than the back feed dogs.
• Slightly increase this setting when you want to prevent lightweight or stretchy fabrics from becoming wavy as they are serged. The increased rate of the front feed dogs counteracts the natural tendency of these fabrics to stretch out under the presser foot.
• For example, when serging the edge of a stretchy fabric, a higher differential feed setting can help achieve a smooth, flat seam that retains the fabric’s elasticity.
• Maximum number (usually 2)  is ideal for creating gathers.

✅Related tutorial: All About Serger Needles

Decreasing the Differential Feed (Setting Below N)

• Lowering the differential feed setting (to a number like 0.7 or 0.6) slows down the front feed dogs relative to the back feed dogs.
• This lower setting is typically used to stretch the fabric slightly as it is being serged. 
• This technique is particularly useful for creating decorative effects like lettuce hems on knit fabrics. 

Keep in mind that the exact settings and their effects can vary slightly from serger to serger, so it’s always a good idea to do a test drive on some scrap fabric. Adjust the dial, run some fabric through, and observe the results.  

So go ahead, give that dial a twirl. 

Creating Gathers with a Differential Feed

#1. Increase Differential Feed: Set the differential feed to a higher number, usually 2. 

#2. Lengthen the Stitches: Turn up the stitch length to further enhance the gathering effect. Longer stitches mean more fabric is pulled through with each cycle, adding to the ruffles’ fullness.

✅Related tutorial: What is the stitch length and how to adjust it for different fabrics – a sewing tutorial

#3. Increase the Presser Foot Pressure (optional): You might need to adjust the presser foot pressure to achieve the gathering effect.

#4. Test Your Settings: It’s crucial to test these settings on a scrap piece of the same fabric you’ll be using for your project. Each fabric behaves differently, and testing allows you to fine-tune the settings for the best results.

It’s always a good idea to refer to your serger’s manual for specific instructions related to your machine model, as some models might have different settings or recommendations. The manual will provide the most accurate guidance for achieving the best results with your particular serger.

Sergers easily create gathers for lightweight fabrics. The serger’s differential feed makes it a simple task, and I am always amazed to see how quickly and beautifully some lightweight fabrics (chiffon, tulle, or a breezy georgette) respond, bunching up into soft, even gathers.

Sometimes, I even gather medium-weight fabrics like quilting cotton. I can usually get a nice amount of gathers, perfect for a summer dress or a skirt with a bit of body. The cotton doesn’t bunch up as much as the lighter fabrics though but I can achieve a pretty satisfying result. 

However, I’ve never been able to gather heavyweight materials effectively with my serger. Fabrics like denim or upholstery material are just too robust and don’t seem to gather nicely. For those heavier fabrics, I usually have to resort to the traditional method of basting and pulling the threads by hand to get the gathers I need. It’s more time-consuming and less efficient, but sometimes the old ways are the only ways when you’re dealing with the tough stuff. 

Creating a Lettuce Hem with a Differential Feed

Creating a lettuce hem with a serger is one of my favorite techniques to add a playful, wavy edge to knit fabrics. It’s a detail that really showcases the capabilities of the differential feed.

Here’s how I go about it. 

#1. Prepare the Serger: I set up my serger for a rolled hem, which usually means changing the settings to a narrow stitch width and a short stitch length. The exact setup can vary depending on the serger model, so I always check the manual to ensure I’m doing it right.

✅Related tutorial: How to Make a Rolled Hem with a Serger:  Get Professional Results

#2. Adjust the Differential Feed: Next, I reduce the differential feed to a lower setting, often between 0.6 and 0.7, depending on the fabric and the serger. This is what gives the lettuce hem its signature look.

#3. Stitch and Stretch: As I serge, I stretch the fabric in front of the presser foot. This added tension enhances the wavy effect of the lettuce hem. It’s a bit of a balancing act – you need just enough stretch to create the waves without distorting the fabric too much.

#4. Test on Scrap Fabric: I always test on a scrap piece first. Different knit fabrics can behave uniquely, so it’s important to adjust the differential feed and the amount of stretch I apply until I get the perfect wave.

#5. Serge Away: Once I’m happy with the test results, I go ahead and serge the actual hem, keeping the fabric stretched evenly to maintain a consistent wavy edge.

Using Differential Feed to Prevent Wavy Seams on Knit Fabrics

Wavy seams on knit fabrics typically occur because the material is stretched during the serging process. The elasticity of knit fabrics means they can easily be distorted if not handled correctly.

✅Related tutorial: All About Sewing Knit Fabric

#1. Increase Differential Feed: To prevent stretching, increase the differential feed slightly above the neutral setting (N). This adjustment helps counteract the stretching of the knit fabric by moving it through the machine more quickly, thereby preventing the fabric from becoming wavy.

#2. Test on Scrap Fabric: Always start by testing on a scrap piece of the knit fabric you’ll be working with. Adjust the differential feed as necessary to achieve a flat seam without any waves or puckers.

#3. Fine-Tune Tensions: Check also your thread tensions. If they’re too tight, they can contribute to the wavy effect. Adjust the tensions to ensure they’re balanced and appropriate for the weight and stretch of your knit fabric.

#4. Do Not Stretch the Fabric: When serging, avoid pulling or stretching the fabric. Let the feed dogs move the fabric through naturally, guiding it gently with your hands.

#5. Use a Light Touch: Keep your hands light on the fabric, especially when serging curves or corners. Too much pressure can cause the fabric to stretch and result in a wavy seam.

Mastering Differential Feed: A Practical Guide to Altering a Pleated Chiffon Skirt 

Now let me share more about my experience with differential feed in my recent alteration project. So that the tips I shared above are not just theoretical but tested and proven in actual sewing projects.

I had this beautiful pleated chiffon skirt that was too long and had a waistband that was too tight for comfort.

My goal was to make it shorter and replace the elastic to ensure a better fit. After removing the waistband and cutting the skirt and its lining to the desired length, I faced the challenge of aligning the now-too-wide pleated chiffon with the narrower lining. Because once I cut the pleated chiffon, it turned out to be significantly wider than the waist of the lining.

To address this, I turned to my serger. I set the differential feed to 2, which is perfect for gathering lightweight fabric. As I serged along the top edge of the chiffon, the increased differential feed gathered the fabric, bringing it down to the same width as the lining.

So the differential feed did exactly what it’s designed to do, creating even gathers and bringing the fabric to the desired width.

Once the gathering was complete, I attached a new elastic waistband with my coverstitch machine but this part of the process is a story for another tutorial.

Now the skirt fits me just right. The length is exactly where I wanted it, and the new elastic waistband is comfortable and snug without being too tight. I’m really pleased with how it turned out. Not only does the skirt fit nicely, but I also enjoy wearing it. It’s a great feeling to be able to breathe new life into a garment and make it work for you.

I hope you see now that understanding your serger’s capabilities can have a direct and positive impact on your sewing projects.

If you prefer a visual guide, take a look at my YouTube video. It’s perfect for those who’d rather watch a handy tutorial on serger differential feed than read about it.

Did you find this tutorial helpful? If so, save this pin (see below) on your sewing board so you can come to this tutorial later when you are ready to use differential feed on your serger, and follow me on Pinterest for more tips, tutorials, and inspiration!

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