Using a twin needle can seem a little intimidating at first, but once you get the hang of it, it’s a fantastic technique to have in your sewing toolkit. Twin needles are great for finishing hems—especially on knit fabrics—and for adding clean, decorative double lines of stitching.
Don’t worry if it feels a bit tricky at first. Like with shirring, practice makes perfect, and soon you’ll be confidently hemming your garments with a polished, professional look.
What is a twin needle?
A twin needle (sometimes called a double needle) has two needles attached to one shank. When you sew with it, the machine creates two straight stitches on the top side of the fabric and a zigzag-style stitch on the bottom. This allows the fabric to stretch a little, which makes it ideal for hemming stretch fabrics like jersey or ribbed knit.
Twin needles come in different sizes and widths, so be sure to check what works best for your fabric. The number on the package usually looks something like “4.0/75,” where the first number refers to the space between the needles (in millimeters) and the second is the needle size.
Photo: Bernina
How to thread a twin needle
Most modern sewing machines can use a twin needle as long as they have a zigzag setting and a wide enough needle plate. Here’s how to get started:
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Install the twin needle just like a regular needle.
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Thread your machine with two spools of thread. If you don’t have a second spool pin, you can place one spool in your bobbin stand.
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Thread both needles separately but follow the same threading path. When you get to the needle, simply guide one thread through each eye. Look at the below photos for support. You can see that one thread does every step except for the tension area by the needle.
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Use a straight stitch setting. You can only use a straight stitch with a twin needle —don’t use zigzag or decorative stitches unless your manual says it’s safe.
Make sure to test your stitch on a scrap piece of fabric before sewing on your actual garment.
Finishing your garment
When using a twin needle for hems, fold up your fabric and press it in place before stitching from the right side. This gives a neat, professional-looking finish on the outside, and the zigzag underneath allows the hem to stretch without breaking.
Important: You cannot backstitch with a twin needle. This will tangle the thread. To prevent the stitches from getting untangled after sewing and to get the most professional finish, you can slightly overlap the stitches when you finish. Then with a hand-sewing needle, pull the front facing thread to the 'wrong' side of the fabric. Now you can create a knot with the threads to prevent untangling.
Remember, the double stitch appears on the top of the fabric, so always sew with the right side facing up.
Using a twin needle takes a bit of patience at first, but once you get the hang of it, it opens up a lot of new possibilities—especially for finishing knit garments at home.
So don’t be discouraged if it’s a bit fiddly in the beginning. Keep practicing, and feel free to reach out with any questions you might have!
Troubleshooting: Preventing Tunneling
Tunneling happens when the fabric puckers between the two lines of stitching, creating a raised ridge. It’s a common issue when using a twin needle, especially on lightweight or stretchy fabrics. To prevent tunneling, try the following tips:
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Use a stretch or ballpoint twin needle for knit fabrics—they’re designed to glide between fibers, not pierce them.
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Adjust the upper thread tension—lowering it slightly can help reduce puckering.
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Use a stabilizer—placing a piece of water-soluble or tear-away stabilizer under the fabric can keep it flat and smooth while you sew.
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Try a walking foot—this can help feed the fabric more evenly.
Play around with these settings on a scrap piece before sewing your final hem. With a bit of experimenting, you’ll find what works best for your fabric and machine.
Photo: reddit