tips and tricks for twin needle hemming


Our regular contributor, Shelley, is back today with some fantastic tips for twin needle hemming on knit fabrics. Let’s hear more from the lady herself.

Have you made any garments for your kids, or yourself, using knit fabrics? There’s been lots of inspiration for t-shirt sewing recently and I’ve realised that a lot of the tutorials and pattern modifications that I’ve shared here in the past have involved knit sewing. Today I want to tell you the story of my history with twin needle hemming. It’s part sewing evolution story, part cautionary tale and hopefully a bit useful. Please feel free to share any tips or tricks you might have as well in the comments below.

Tips and tricks for twin needle hemming

When I first started to sew knit garments for my kids I used a zig zag stitch on my hems, or experimented with a sewing machine lettuce hem and I was happy. For the most part. But I dreamed of a knit hem that looked like the shop bought t-shirts.

I heard about twin needles and set off to find out if my sewing machine could use them and to buy one.

Tips and tricks for twin needle hemming

I was happy to learn that pretty much any sewing machine can use a twin needle and so I purchased one. Just one twin needle for a beginner. I went home and immediately broke my new twin needle as my sewing machine was still set in zig zag mode after constructing my t-shirt. First lesson learned.

Twin needles come in various widths and needle types. I probably only need to have the stretch twin needles, but I confess to being a bit blasé about needle types, hence that Universal one has snuck its way into the collection. I tend to use a 4mm twin needle for kids garments and a 6mm for adult garments, purely because that’s what looks about right to me.

So I bought another twin needle, and a spare, and stitched my first double hems. They looked great from the front:

Tips and tricks for twin needle hemming

Although perhaps not quite right from the back.

Tips and tricks for twin needle hemming

It was only after a couple of wears that I noticed the kids were breaking the hems. The bobbin thread was snapping when stretched and the needle threads all “popped.” I realized that for the hem to stretch the bobbin thread needed to zig and zag more in order for it to have the potential to lengthen.

When the needle threads appear on the underside of the fabric like that, the sewing machine manual will tell you to increase your needle thread tension. So I did.

Here you can see, from left to right, the effect of increasing needle thread tension on the bobbin thread:

Tips and tricks for twin needle hemming

The problem with increasing the needle thread is that, while the bobbin thread zig zags nicely, the needle threads draw together and the double hem ends up creating a tunnel effect. Here are the same three hems seen in profile. The increased needle tension gives this lumpy seam finish seen on the right.

Tips and tricks for twin needle hemming

And still, they broke.

Now, that happens with shop bought garments too, but I wasn’t satisfied with my lumpy one-wear-hems. I posed the question of what to do on the forum and Liesl introduced me to Woolly Nylon.

Woolly Nylon

Woolly Nylon is a multi-filament nylon thread that is wonderfully strong and has a bit of stretch to it. You’ll find it in a few colors, but you can probably get away with just having one cone each of black and white, or perhaps even only grey.

By using woolly nylon for the bobbin thread you get a stronger, stretchier double hem. However, the woolly nylon has more “drag” than a normal thread, so the tension problems were exacerbated.

I figured if I couldn’t raise the needle thread tension any further, and I didn’t want to anyway because of the tunneling, I’d have to lower the bobbin thread tension.

How you do this will be different for every machine, but I’m sure it’s achievable for every machine. I imagine there are fancy machines out there with bobbin tension dials. If you have one, then lucky you. Dial down your tension, sew your hem, then dial it back up for regular sewing.

My basic machine has a bobbin casing, like this:

Tips and tricks for twin needle hemming

When you remove the footplate and take the bobbin casing out you’ll see a little screw that can be adjusted to change the tension.

TIps and tricks for twin needle hemming

I was a bit wary of fiddling too much with the screw, as I worried I might not get it back to a good setting for regular sewing. So I made a small financial outlay for a second casing. That one I dialled all the way out to “super loose”.

Thankfully, my new super loose bobbin casing doesn’t have the red arrow of my original, so I can tell them apart. A bit of nail varnish or correction fluid would work to mark which was which had they looked identical.

Tips and tricks for twin needle hemming

And now I could sew a nice, flat, strong and stretchy twin needle hem.

Tips and tricks for twin needle hemming

Tips and tricks for twin needle hemming

You can see here that I’m using a cotton lycra with its notoriously curly edge. It’s a great fabric for sewing kid’s clothes, but trying to hem the unfinished edge can be a nightmare.

At this point in the story I was hooked on sewing knit garments for my kids (no ironing!) and I was now the happy owner of an overlocker. Finishing the fabric edge with the overlocker makes it lie flat, behave itself better, and adds some stability to the fabric to help prevent the dreaded tunneling.

Tips and tricks for twin needle hemming

I thought I had twin needle hems licked and then I started to sew more for myself. What was working on cotton lycra was not working with lightweight jersey fabrics.

To prevent tunneling when sewing a lightweight knit fabric you’ll need to stabilize the fabric further. Overlocking helps, but a thin strip of knit interfacing, fusible webbing, or a wash away hem stabilizer will do wonders. Where maintaining the fabric’s full stretch is crucial, the wash away hem stabilizer will be the best product for the job. Buy bigger sheets and use a ruler and rotary cutter to cut it into 1/4″ strips to make it cost effective.

Here’s a rayon jersey that’s hemmed with my final “perfected” twin needle hem on the left, and then again on the right, but this time with a thin strip of stabiliser underneath.

Tips and tricks for twin needle hemming

It takes me only a minute to swap over my bobbin casings and insert the twin needle. When I remember to, I also swap to a walking foot. This does help prevent the fabric getting stretched out as you sew, and stops me getting stuck on the side seam bumps. I’m not convinced it’s essential for hemming knits, rather it’s the icing on the cake.

Tips and tricks for twin needle hemming

Sometimes the needle threads get a bit twisty and knotted together. If you’re going to hem a dozen t-shirts in a row, you may have to stop and rethread your needles half way through. I’ve definitely noticed that using cheap overlocker type thread for the needle threads leads to a hot knotty mess quite quickly. Stick to good quality threads up top.

Does it make any difference which direction the two needle threads unwind in? I honestly don’t think it does. But, if things are getting knotty, you won’t do any harm in flipping over the second thread spool. I never remember to make a note so I can record any statistically significant difference….

I’m happy to say that when I rummaged through my kid’s wardrobes to find a t-shirt with a “popped” hem to take a photo, I couldn’t find any. They’ve all been outgrown and handed on now and become someone else’s mending problem!

Shelley.

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50 Comments

  1. Emily

    Thanks for this article – I’ve also had the problem with my kids popping the hems of their shirts! So frustrating. I’ll have to try out lowering the tension on the bobbin thread. I was just looking on Amazon and they actually sell a low-tension bobbin case for my Janome, specially marked with a little blue triangle.

    1. Oh that’s a nice solution Emily

  2. Enbee

    Thanks for this! I’d trawled through the forums and have implemented many of these tricks with my double needle hems. I will say that for my machine, a walking foot is *essential* for working with the double needle. If I forget to use it, the leftmost needle thread drops stitches like crazy.

    1. Best advice is always do what worked last time! Thanks for the kind comment.

  3. All great tips. I got so frustrated with my machine (which hates doing any sort of zig zag on knits) that I finally got a coverstitch. But before I did that I did find that my machine much preferred having both the threads come off the two spools in different directions when using a twin needle. Otherwise I would get tangles. But this may just be my machine’s personal quirks.

    1. I almost wish I hadn’t figured this out so I could justify a coverstitch machine! I recalled your winding direction troubles, so I’m not dismissing it as real…

  4. Marcy

    Thank you, awesome timing! I just bought a twin needle so I can hem the Maritime shirt I’m making for myself. I really appreciate reading all these tips before I try it out.

    1. Great! Glad to be of help, and I’m sure you’ll love the Maritime pattern.

  5. Sherry Kelly

    According to Nancy Zieman, the 2 thread spools should be unwinding in opposite directions. I tried it, no thread tangling!

    1. Great, glad to hear it works for you. We need a randomized, double blind trial of spool winding directions! 🙂 I flip one if I’m getting tangles, but I can say conclusively if it makes a difference for me….

  6. Su

    Thanks for this very clear article. Good to have the info in one place.

    Shelley can you answer something for me please?

    I’ve seen that you should wind woolly nylon onto bobbins by hand, so it is not too tight… but how do you judge how loose/tight to wind it?

    1. Su, I just heard that a day or two after writing this article. I guess if you hand wind the bobbin it will be lower tension so you may not need the altered bobbin casing tension. I wind mine by machine. The big spools don’t fit on the machine so I hold the bottom of the spool, keeping my fingers clear of the thread, and hold it horizontally as if it were on the machine.
      Hope that helps.

      1. Su

        Oh wow, that’s much tighter than I imagined! That’s a very helpful guide – been trying to find the answer to that for a while, so many thanks 🙂

      2. Leaving this here for future readers – I found out the hard way today that if you thread your bobbin by machine with this stuff, you should use a metal bobbin! I should post a picture somewhere – my popped, expanded plastic bobbin is pretty impressive.

      3. Wow, Enbee, that’s crazy! I haven’t had that happen with plastic bobbins (yet?) and my machine certainly doesn’t like sewing with metal bobbins.

  7. Wooly nylon thread has just been added to my shopping list. Great article Shelley. You always make me laugh!

    1. Anna I’ll swap you a few pre-wound bobbins for that tote bag tutorial! 🙂

  8. Great post, Shelley. I’m all too familiar with the ‘tunnel’ effect… definitely going to try that stabiliser tip!

    1. Cheers Marisa. I think Anna buys hers online from stitch56 if you need a local source. (I chop up the Spotlight sheet stuff)

  9. my tip is: buy the twin needles when needles are on sale, they can be pricey :o)

    1. Very good advice Colette!

  10. Renee

    Thanks Shelley! I’ve been looking at my kids’ popped hems. Now I know what to do next time.

    1. I hope it helps Renee. I no longer mind so much if my kids tuck their knees up under their t-shirts!

  11. Great post, Lightning. I flip one of my spools when I double-needle hem and have found that it really does help to prevent tangling.

    1. Looks like the flipping advocates have the numbers. I’ll have to start paying more attention to my methodology!

  12. Great Post! I learned a lot from this, I am off to buy some woolly nylon now! 🙂

    1. Thanks Maaike!

  13. sarah

    I’m unclear on something. If I need a stretchy hem, will a regular twin needle using the straight stitch result in a stretchy stitch? Or do you need a “stretch twin needle” for the hem to be stretchy? Thank you!

    1. Sarah the stretch comes from the zig zagging of the bobbin thread and it’s ability to straighten and lengthen when stretched. That happens regardless of what type of twin needle you use.
      The “type” of twin needle is more to do with the sort of fabric you’re sewing. A “stretch” or “ball point” needle is used for sewing knit fabrics to avoid damaging the fibres of the fabric and holes appearing along your seams.
      I hope that helps.
      I assume that twin needle use in woven/non stretch fabrics would be purely decorative (eg perfect parallel topstitching). I’ve never done it that way, so I don’t know why one would use a Universal twin needle, or why I ended up buying one… 🙂
      Hope that helped.

  14. Thanks for the tips in hemming knits with double needle! I’ll have to definitively try the Woolly Nylon.

  15. Lots of great snippets! I’ve been struggling with mine and given up on my twin needle in a bit of a huff. Will try your suggestions!

  16. HannaLouise

    A universal needle is handy when stitching poly cotton or a polyester with slight give as it is between a sharp and a ball point needle.
    Wind woolly nylon onto the bobbin by slowing down the rate of winding if you have this feature available – not all machines accept metal bobbins.

  17. Maria

    What brand of “walking foot” do you use? I just purchased a mid priced Juki and in the shop where I bought it, we tried two brands and neither one would allow the twin needle to pass through the bobbin plate. I do like your solution using the secondary bobbin case with a reduced tension.

    1. Maria

      I’ve also used knit stay tape in the hem of stretchy fabrics prior to using the twin needles. But it still changes the lay of the hem line. I bet the walking foot would help this.

      1. A walking foot does seem to be the icing on the cake when it comes to knit hems for me. But I know other people for whom it’s more like the eggs in the cake, as their machine just hates knits without it. The important thing is to find a walking foot that fits your machine. They’re not always cheap, but it’s safest to buy the same brand as your machine. A generic model might fit, or it might be a waste of money…

  18. Paula Beaudet

    What about using the stretch stitch selection with the twin needle and the walking foot?I have just begun to sew. will this tackle the problem of hem breaking?

    1. Hi Paula, sorry for the late reply. You MUST use a straight stitch as any type of stitch that moves the needle side to side will smash your twin needle into the foot plate (done that by accident). If, by stretch stitch, you mean the forwards a bit, backwards a bit, triple stitch; I suspect it would turn into a hot mess of bobbin thread tangle. I’m lost tempted to experiment on your behalf…. 😉

  19. Laura

    Question in regards to twin needles use as a top stitch/hem… I’m starting to get into top stitching neck bands and I can’t figure out how, if possible to make the top stitch two parallel straight lines and the bottom zig zag.. i know I need to get wholly nylon thread for my bobbin to help make the neckline stretch without breaking the thread but I swear I’ve seen ppl use that option but can’t seem to get any help from my owners manual. Help!

    1. Laura that is exactly what you get as soon as you use a twin needle: two parallel lines of needle stitching with the bobbin thread zig zag going back and forward underneath. Just insert the twin needle, thread both eyes, select a straight stitch and there you go. Everything else I’ve described is just tinkering to make it a more, durable hem. Good luck!

  20. tess66

    Thank you! thank you! thank you!!! You saved my nerves… <3

  21. loopner

    I have used twin needles in the past, with good results. I now own a newer Janome and use a walking foot almost all the time.
    I am not having luck with the ball point twin needle and am baffled as to why. It seems to stitch well for a bit then begins knocking and stitching badly. I always have the two thread spools coming off in different directions. I am beginning to think it is my walking foot in combo with the twin needle that is the problem. Any hints would be appreciated

    1. That happens to me with my walking foot too sometimes (also a Janome user) and I find it’s because the screw holding the walking foot to the bar comes loose after stitching for a bit. It never comes loose with the regular foot, so I always forget about it potentially happening. Could that be it?

  22. Jos

    Thank you! I found your tips and bought another bobbin casing, something I would never have thought of. It took me quite some time to find a good balanced stretchy hem. But it worked in the end! Your article is the only one that discusses technical problems with the twin needle in such depth. I am so glad you took the time to write it down!

    1. Thanks Jos, that comment really made my day! I’m so glad you’ve got the double needle thing working for you now.

  23. Tangled threads

    I’ve used your twin needle / woolly nylon method with great success turning my 40 yr old machine into a great stretch fabric
    hemming tool. I’ve ordered some of the texturized polyester thread to try out next.

  24. Tangled threads

    Update on my previous comment. I received the textured polyester thread and it appears to work similar to the woolly nylon.
    If so, this would be a good choice due the better temperature tolerance of polyester over nylon. Also, right now the polyester
    textured thread is available at a great price. I bought a cone of 8500 yrds for $3.00. Even at the usual price of $13.00 it’s probably the last time I’ll have to purchase it.

    1. That’s great to hear. I guess if you hot wash, or tumble dry garments then heat could be a concern.

  25. Karen

    Thank you! I was trying to use a twin needle for the first time and having no good results. The combination of the walking foot, mounting the thread spools in the reverse of each other, cleaning out my bobbin and tension areas with a fine brush all helped. But I did not really have success until I hand wound some fuzzy/textured thread on the bobbin. Still had one bobbin thread break, but really, beautiful results. Whew! (it was a hem I was doing for my mom)

    1. Nothing like sewing for your mum to increase the pressure! Glad you got a hem you were happy with.

  26. Judy

    Thank you! And yes, having the spools unwind in opposite directions was the tip that is absolutely essential for some machines, mine in particular (jamming and bird’s nest form on bottom side every inch otherwise.)

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