To test sewing knits with a sewing machine, I sewed 90 combinations of presser foot, upper thread tension, and stretch needle. Check out my findings to save you headaches when sewing with knits!

I am sergerless. At Van Handel Headquarters, I’m sewing knits with a sewing machine.

And, for the most part, sewing knits without a serger works just swell for me. I’ve sewn scuba knit, sweatshirt fleece, ponte, heavy sweater knit, cotton spandex, and more on my Babylock Elizabeth machine and been happy with the results.

And then I sewed my Bridgetown backless dress. And I scowled a lot.

The dress turned out great, and I’m not worried about it falling apart or anything. The problem was the experience sewing with a thin, stretchy, slinky, drapey fabric (a rayon-spandex blend). I fought my machine the whole time, no matter how often I changed presser feet, upper thread tension, and needles. The correct combo eluded me.

Throughout sewing Bridgetown, I thought to myself, “There’s no reason this should be this difficult.”

That’s when I came up with the following sewing experiment.

If you’re sewing knits with a sewing machine, keep reading for my evaluation of 90 (!!!) combinations of fabric layers, presser feet, upper thread tension, and needles. My takeaways from this exercise will help you sew stretchy knits with fewer headaches!

How I set up my experiment for sewing knits with a sewing machine

I tested the different combos on two fabrics: the rayon-spandex knit I used for my Bridgetown backless and a bamboo knit. They are similar in drape, weight, and stretch. They’re definitely not stable knits that handle like wovens.

I cut the knits into (approximately) 3-by-4-inch rectangles, and I tested the same stretch stitch on two, three, four, five, and six layers of fabric.

Here’s a look at the other variables:

I used a stretch stitch for sewing knits with a sewing machine.

I choose my favorite stretch stitch, the “lightning” stitch. The 2.0 width and 4.0 length are the default. I prefer the lightning stitch to the triple stretch stitch (see above) because I find it’s easier to unpick, should the occasion arise.

I used all-purpose polyester thread for sewing knits with a sewing machine.

For thread, I used two all-purpose, 100 percent poly options: pink for the top thread, white for the bobbin thread.

I used stretch 90/14 and 75/11 needles for sewing knits with a sewing machine.

I tested two stretch needles: 75/11 (smaller) and 90/14 (affiliate links). I bought these needles at Jo-Ann.

I varied the upper thread tension for my test sewing knits with a sewing machine.I varied between 3 (looser), 4 (medium), and 5 (tighter). The middle setting on my machine is 4. The upper thread tension goes down to 0 and up to 9.

When performing my test for sewing knits with a sewing machine, I used a stitch guide foot, a walking foot, and a zig-zag foot.

I varied between three feet:

Stitch guide, which is my everyday foot. It helps me get accurate seam allowances, and I love it so much for that. This foot came with my machine.
Walking. This foot did not come with my machine; I think it was about $50.
Zig-zag. This is the “default” foot for my machine, I think because you can perform the most stitches with it. It came with the machine.

I photographed the upper thread and bobbin thread on each test scrap, and next to each photo is a tag that highlights the needle, foot, and upper thread tension. (FYI, I goofed when making the tags; 5 is labeled “loose” tension and 3 is labeled “tight” tension. I scratched out the incorrect labels. Remember: 5 = Tight, 3 = Loose.)

Now that you’re up to speed on what I’m working with, let’s dive into the results! Under each collage I highlighted my key takeaway (look for “Takeaway” in bold; I know it gets kinda lost under these big images), and for each layer set, I’ve picked the needle-foot-tension combo that I think worked best. (Also: If you’re reading this on a mobile device, you might want to switch to a desktop monitor for the greatest detail.)

Sewing 2 layers of stretchy knit fabric

The results of sewing two layers with a stitch guide foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: The winner here is tight tension. Look at how much top thread you can see on the bottom when the tension is loose! For the record, you shouldn’t see ANY top thread on the bottom or bobbin thread on the top.

 

The results of sewing two layers with a stitch guide foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension wins. The top thread isn’t quite as bad on the bottom with the bigger needle.

 

The results of sewing two layers with a walking foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension wins.

 

The results of sewing two layers with a walking foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension wins.

 

The results of sewing two layers with a zig-zag foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension wins.

 

The results of sewing two layers with a zig-zag foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits! Takeaway: Tight tension wins.

Observations about sewing 2 layers

Most of the time, you’re sewing two layers of fabric. It’s like 95 percent of all the sewing you ever do. These combos are IMPORTANT!

The tight 5 tension worked best with all feet and both needles. And it looks like I could have cranked up the tension a bit more. The top thread was comparable across all combos.

To my eye, the 75/11 needle-walking foot-5 tight combo is best for two layers. The 75/11 needle-zig-zag foot-5 tight looked good, too.

Sewing 3 layers of stretchy knit fabric

The results of sewing three layers with a stitch guide foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension wins. Man, the top thread gets loopy on the bottom when the tension is loose!

 

The results of sewing three layers with a stitch guide foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension wins. The bigger needle handles the loose tension better than the smaller needle.

 

The results of sewing three layers with a walking foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension wins, but medium tension is close behind.

 

The results of sewing three layers with a walking foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension FTW.

 

The results of sewing three layers with a zig-zag foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Clearly it’s tight tension.

 

The results of sewing three layers with a zig-zag foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension (starting to feel like a broken record).

Observations about sewing 3 layers

Tight tension is the winner throughout. You can start to see the growing impact of the loose tension on the upper thread as it’s pulled to the back in bigger loops.

For my money, I think 90/14 needle-walking foot-5 tight combo was the best for three layers.

Sewing 4 layers of stretchy knit fabric

The results of sewing four layers with a stitch guide foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: I think medium tension looks best here. The tight tension swatch looks like it’s stretched out of shape.

 

The results of sewing four layers with a stitch guide foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: The tight tension swatch looks most balanced.

 

The results of sewing four layers with a walking foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension might be slightly better than medium, but it’s a toss-up.

 

The results of sewing four layers with a walking foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension. The upper thread is nearly invisible on the bottom side of the swatch.

 

The results of sewing four layers with a zig-zag foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension.

 

The results of sewing four layers with a zig-zag foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension, yet again! We’re starting to see the upper thread stitching on top start to look less than wonderful.

Observations about sewing 4 layers

With four layers, loose upper thread tension is even more pronounced than with three layers. The top thread goes loopy, and the bottom (bobbin) thread goes straight, making it more likely to break.

I think the 90/14 needle-walking foot-5 tight combo is slightly better than its 74/11 counterpart for sewing four layers. Four layers of any fabric is a lot to sew through, so it makes sense to pick a bigger needle.

Sewing 5 layers of stretchy knit fabric

The results of sewing five layers with a stitch guide foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension looks slightly better than medium tension. Loose ain’t even in the game.

 

The results of sewing five layers with a stitch guide foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension again. The 90/14 needle looks nicer than the 75/11 needle.

 

The results of sewing five layers with a walking foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension wins.

 

The results of sewing five layers with a walking foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension.

 

The results of sewing five layers with a zig-zag foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension.

 

The results of sewing five layers with a zig-zag foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: In a twist, I’m going with medium tension over tight tension, only because you can see on the top side of the tight tension swatch how much the line of stitching pulls the fabric. There was too much pressure.

Observations about sewing 5 layers

Five layers becomes a struggle, and we know this because the stitching starts to pull the fabric. It’s tough for the layers to travel under the pressure foot.

I think the 90/14 needle-walking-5 tight combo is our winner for five layers. The zipper and stitch guide feet put more pressure on the layers than the walking foot.

Sewing 6 layers of stretchy knit fabric

The results of sewing six layers with a stitch guide foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Medium tension takes it. I had a hard time controlling the line of stitching for tight tension, and it waves. Loose tension = yikes.

 

The results of sewing six layers with a stitch guide foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: The line of stitching with medium tension distorts the fabric the least, but they’re all pretty bad.

 

The results of sewing six layers with a walking foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Tight tension has it. The upper thread stitching on the top side of the medium swatch is uneven.

 

The results of sewing six layers with a walking foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: This is a race to the bottom. Of the three, tight tension is the least bad. The stitching for all the swatches is uneven, which means the feed dogs struggled to keep the fabric layers moving evenly.

 

The results of sewing six layers with a zig-zag foot and 75/11 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Medium tension wins. The stitching is more even than tight tension. Loose tension is a hot mess.

 

The results of sewing six layers with a zig-zag foot and 90/14 stretch needle. Check out my findings to save you headaches when sewing with knits!

Takeaway: Medium tension takes it, because the stitching distorts the fabric less than tight tension.

Observations about sewing 6 layers

The winner here for sewing six layers is the 75/11 needle-walking foot-5 tight combo. Also observed: Sewing six layers of fabric is a pain in the keister. To ensure even stitches, you have to sew slowly — and even then, it’s likely the sewing machine will struggle. It’s a tall order for the feed dogs.

Sewing knits tips: What 90 combinations of needle-foot-tension taught me

I hope you’re still with me, fellow sewists! Here’s a high-level recap (aka TL;DR) of what we’ve learned about sewing through different numbers of fabric layers:

2 layers

Best choice: 75/11 needle-walking foot-5 tight. The zipper foot also performed well on two layers, which is good news for sewists who don’t have a walking foot.

3 layers

Best choice: 90/14 needle-walking foot-5 tight. With three layers, loose tension starts to become an issue.

4 layers

Best choice: 90/14 needle-walking foot-5 tight. Loose tension on the upper thread results in the bobbin thread going straight — making the stitching more prone to breaking.

5 layers

Best choice: 90/14 needle-walking foot-5 tight. With five layers, pressure from the presser foot starts to pull the fabric as it’s stitched.

6 layers

Best choice: 75/11 needle-walking foot-5 tight. With six layers, it was tough to get even stitches, which means the feed dogs were challenged. It’s also worth noting that for four of the six combos, 4 medium tension produced the best result.

What does all this mean?

Sewists sewing knits on a sewing machine should walk away with four big insights from my experiment:

1.) Consider investing in a walking foot. The walking foot produced the best results, period. The walking foot, with its own set of feed dogs, gently guides fabric layers without stretching them. It also seems to apply less pressure to the fabric (which brings me to insight No. 2).

2.) Consider adjusting your presser foot pressure. The more I sewed these swatches, the more I realized that the pressure coming down on the fabric contributed to it stretching. I didn’t want to add another variable to this experiment, so I didn’t touch my pressure dial. (I plan to do a similar experiment where I vary presser foot pressure! Stay tuned.) If you feel like your foot is pushing your fabric forward (I found this happened when sewing many layers of fabric), test reducing foot pressure.

3.) Increase the upper thread tension. Sewing these combos showed me the importance of balanced tension between the upper and bobbin threads. If the upper thread doesn’t have enough tension, the bobbin thread is likely to break (and kill your seam). I’m going to pay greater attention to tension and not assume the middle 4 setting is right for every project.

4.) Don’t freak about needles. The smaller needle worked best for two layers of fabric — and six layers of fabric. Plot twist! To me, this experiment shows the foot is more important to than the (stretch) needle size when you’re sewing knits.

What could have been better

Two things stick out to me that could have improved this experiment:

1.) Use contrasting thread. The pink upper thread looked fine on the teal stripe knit… but it got lost on the printed knit. Sorry, guys. I should have sewn with yellow or something else bright and contrast-y.

2.) Sew on the grain. When I cut all the scraps, I didn’t consider grain. Sewing on the cross-grain may have made a slight difference in the results, especially for the swatches that stretched out.

WHEW, I am exhausted! I hope you’ve enjoyed this tome on sewing knits with a sewing machine. When I was doing keyword research for this post, I came across the question, “Is sewing knits hard?” My answer is: No! There are plenty of wovens that give sewists fits, too. Experiment with your sewing machine (PROTIP: Read the manual! Seriously! It’s filled with secrets!) and take your time. The best part of sewing knits is coming away with comfortable clothes with minimal fitting issues. Stretchy rules!

Over to you: If you’re sewing knits on a sewing machine, what are your top tips? What’s your winning needle-foot-tension combo? What surprised you most about this epic sewing experiment? Do you have additional takeaways? What feedback do you have for ME on how this post went down? I’m all ears; please sound off in comments. And thanks for reading.

P.S. Here are some other sewing resources for you:

How to press scuba knit and more: Tips for working with scuba fabric
Sewing patterns for yoga clothes: 4 yoga sewing patterns, side by side
53 gifts for sewists: The ultimate guide to gifts for sewing lovers

P.P.S. ICYMI, my last blog post was about why I canceled my Seamwork mag subscription, and I got a lot of great comments about it on social media.