How to Fix a Wavy Seam with your Serger's Differential Feed

 
You know how sometimes you just have a gross, wavy, seam? We don't want this. See how wavy and not nice that is?



Hello everybody, and welcome back to the shop. Today, I'm here to talk to you about sergers, specifically about the differential feed feature on your serger. So, if you are sewing some seams maybe on a knit fabric and you're getting this gross, wavy, stitch, and you just want your fabric to be nice and flat, that's something you can correct with your differential feed.

I'm going to show you what the differential feed is, explain what it does, and show you how to adjust it on a few different machines that I have here. If you have a serger, you may see some kind of a dial somewhere on the machine that has these two little shapes; this is pretty much universally the symbol for the differential feed.


So what does this mean? The differential feed dial is going to adjust how your feed dogs work. Unlike a regular sewing machine, some sergers have two sets of feed dogs instead of just one. This is why they can correct that wavy seam. You have two sets of feed dogs and they travel like a conveyor belt that pulls your fabric through. If you have two sets that can go at different speeds, that's called differential feed and that is what is needed to correct the issue of the wavy seam.

See photo below of the two sets of feed dogs on my Juki MO-735.


Differential feed is an amazing machine feature. It fixes a problem that really needed a solution.

Here is how to use it:
Look at your differential feed dial.  It always starts with a .7. I don't really know why.

It has an N, which means neutral maybe or normal. It's kind of like 1.

Usually there are some other numbers, like 1.5 and 2.

Let's break down those options:
If you set it to the N, it's going to make both sets of feed dogs travel at the same speed. It's going to be just regular, like there's not a differential feed. This is the settnig to use for a regular fabric, [no stretch]. Examples: quilting cotton, canvas.

Want to sew with knits and you're getting that wavy seam? Turn it up. Maybe to 1.5, maybe to 2. It's going to depend on your fabric. Super stretchy fabrics are going to require you to turn the differential feed setting up to 2. Only mildly stretchy fabrics might only need to be set to 1.5 to smooth out.

Test the stitch! Get a big, long, strip and test sew on a few different settings.  See which one flattens it the stitch out better. Then you'll know that's what setting you're going to use throughout your whole project.  I have some Art Gallery knit fabric here. I'm going to sew along it and we'll see what it does. This is at N.  See video.

Check out that wavy seam. You see what it did? This is when the machine was set to N. Basically, the feed dogs were moving at the same speed, just like a regular sewing machine would. That is just a gross seam. We don't want that. See how wavy and gross that is? I'm going to come over here and change the differential from N to 2, and we're going to try again.

With that change, you can see we got a nice flat edge. It looks so much better. This setting adjustment is just going to make everything lay so nice. If you've worked with knits and all your seams are just kind of wavy, this the solution for you.  If you feel like you can't do anything about it other than iron it, or use some kind of fusible adhesive product, you're going to be so happy once you discover the differential feed. I know I was.

You also might wonder what that .7 setting was for. That is actually to fix a puckering issue that occurs when sewing with tightly woven, thin fabrics. Examples: cotton voile, cotton lawn. If you're stitching and you see the fabric is puckering up all along the stitches, that can be remedied by turning the differential feed setting from N down to .7.

For this test I'm going to set my machine to a rolled hem, because that's what I'd typically stitch on this type of fabric. I want to make sure I can fix the problem in the way that I'll be using it.  To make the rolled hem I have to change a few settings on my serger, including the following: I disengaged that stitch finger. I turned the lower looper from 4 up to 8. I turned my stitch length down to 1.5. Now the machine is set up for a rolled hem. Let's send the fabric through with the differential set at N, just to show you what happens. 

Do you see the puckering here on this tightly woven cotton? See how it just kind of puckers along the stitches just a little bit? Now I'm going to take the differential and turn it down to .7. That's as low as it goes. I'm going to do the rolled hem again. 

Okay. And here is the second time with the differential feed turned down to .7.

It looks pretty flat and free of puckers. Compare to the first one we did.

See those puckers along it? See all that? Versus this one that we did with the differential set to .7.  You can see in the video how you can correct these issues by changing the differential feed.

All right, friends. I hope that helped you understand the differential feed on your serger. If you did try it, did anything happen?  If you have anything to say, leave a comment on the YouTube video. I would love to know more about your experience. If you have any other questions about sergers or sewing machines, or anything other potential video topics, feel free to leave a comment about that as well. Please give me a Like if you liked this. Please subscribe to the YouTube channel. Thanks for watching!