If you don’t own a coverlock machine, using a twin needle is the perfect alternative to achieve a professional-looking seam. At first, it can be a little tricky, but when you nail the technique, using a twin needle will save you about half the time when you want topstitching on your garment.
If you don’t have a coverstich machine, the solution to a professionally looking topstitching is the twin needle. There are a few things to consider when choosing what needle to use, so let’s start with the basics.
A twin needle is composed of two needles attached to one shaft, making it possible to sew two identical rows of stitches simultaneously.
It’s commonly used for topstitching around the sleeve edges and hem. But you can use it for some of your sewing machines’ decorative stitches, too, as long as you have the throat plate and presser foot to accommodate for the width of the stitch and the two needles.
You can use a twin needle on both knit and woven fabrics. If you look closely at the seam, you see the threads are crisscrossing on the back of the fabric. This makes the seam stretchy and ideal for hemming garments in knit fabrics like jersey, ITY knit, and stretchy knits for activewear.
Twin needles come in different sizes and widths, from size 1.6/70 for fine fabrics like chiffon and silk to 6.0/100 for heavy-duty fabrics like denim and lofty wools.
Check your sewing machines’ throat plate and presser foot width (use the ones you use for a zigzag stitch).
You do it by “walking” the stitch manually, completing a couple of stitches with the handwheel on your machine. This is especially useful if you’re sewing a decorative stitch with some width.
The point is to make sure the needles fit into the opening of the presser foot and throat plate through the whole width of the stitch, so it’s wide enough that the needle won’t touch the presser foot when you sew.
Insert the twin needle with the groove facing you and the shank’s flat side facing away from you. Make sure the needle is attached all the way up in the needle bar. A stable needle gives the smoothest stitches, and you don’t want the needle to slide out during sewing, safety first!
If your machine has an extra spool pin, you can use it for the second spool of thread. If not, you can either use the bobbin threader pin or sew with two bobbin spools with matching threads on the same spool pin unwinding the thread in opposite directions.
Thread one spool at a time, as usual, except for the last step, where you let the second thread run outside the last thread holder, making sure the two threads don’t tangle.
If you want to have a more detailed look, here’s a handy video on how to thread a twin needle by Threads Magazine.
Make a couple of back stitches at the beginning and end of the seam.
Sew with the right side of the fabric facing you.
Sew slowly and steadily, and do not stretch the fabric. A magnetic seam guide can do wonders and function as a “third hand.”
You sew a curved seam the same way as a straight seam.
Keep an extra eye on the outside edge of the fabric, so you make an even seam.
You can’t get an exact angle on the row of stitches when you turn a corner with a twin needle because the threads will cross each other. Nevertheless, there is a way to sew a corner if you’d like;
Sew the first line of stitches all the way to the end and off of the fabric. Cut the threads, turn your work and stitch the next row, crossing on top of the first one at a 90-degree angle.
There are 3 common errors when using a twin needle:
The fabric between the stitched rows forms a ridge.
Fix by loosening the thread tension, and sample the seam on scrap fabric until you’re happy with the result.
The upper and lower threads don’t catch each other. Fix by using stabilizers like fusible tape or interfacing. Make sure both needles stitch through the enforced fabric, or you’ll end up with a ridge.
Uneven and crooked seams. Try using a fabric guide. To keep an even distance to the fabric edge, you can use a magnetic fabric guide or the quilting arm that came with your sewing machine. You can also place a piece of tape at the right distance from the needle and guide the fabric with your hands. With the tools, however, it’s much easier to get a great result.
It’s practical to pre-press your hem before you sew especially if it’s a rounded edge, but it’s not always the case. Test your seams on scrap pieces of the same fabric you’re sewing, and you’ll be sure what works best.
Use a stabilizing tape the same width as the hem and fuse it right at the fabric’s edge. Then it’ll be easy to simply fold the tape under and topstitch from the right side following the edge of the tape.
It may seem complicated to get those seams perfect from the start but have faith. Go slow, and test every seam on scrap fabric first, and you’ll master the twin needle in no time.
Self-made garments that look like Ready-To-Wear makes them all the more enjoyable to wear, and your confidence working the twin needle will grow by the garment.