How to create a strong faux flat-lock seam with an overlocker.
A cover stitch machine can offer a professional finish for sports and jersey garments. It can create neat hems and flat covered seams that are ideal for sports wear. However unless you plan to make a lot of sports garments or garments that require cover- stitch you may not want to invest in one of these machine as they are a pretty hefty investment price wise.
A cover-stitch machine will offer a super stretchy flat seam that is great for hemming, it can also be useful for covering seams as you can stitch through the centre of fabric. This can be really useful, preventing seams that rub your skin when you are working out. During the development of my latest pattern the Violet leggings I tested out an idea for creating smooth seams that look and like a flatlock seam.
A flatlock seam is usually flat, the two edges of fabric are butted up to one another without overlapping. There is a method of creating a more traditional flatlock seam using an overlocker. It involves using three threads, loosening the needle tension and tightening the lower looper tension. However it is a little tricky and not really strong enough for fitted active wear like leggings.
This method uses a regular overlocker and a standard sewing machine that has a zig-zag stitch. I have worn these leggings quite a few times, the seams have performed really well.
How to create a strong faux flatlock seam.
I highly recommend running some test pieces to check your stitching and make sure you have the correct tension and stitch sizes before working on your garment.
You will need to set your overlocker up with 4 threads and an average stitch length. Your sewing machine will need to be set up with a stretch or ball point needle.
- With wrong sides together stitch your pieces together. It is worth checking the differential feed here. The seam needs to be as flat as possible and definitely not stretched out in anyway. Also check that the tension is correct so that when the seam is pulled it will stretch as you would expect it to, without snapping. Sew the seam trimming to the correct seam allowance as you would if you were sewing the seam with right sides together.
2. Press the seam to one side. Set your sewing machine to a zig-zag stitch. Ideally the stitch width needs to be approximately the width of the overlocked seam. The length should be medium. Again test this on a piece of scrap before sewing the garment.
3. Stitch the seam flat so that the zig-zag stitch holds down the free edge of the overlocked seam.
The reverse of the piece will have enclosed edges offering a smooth seam.
The seam has good stretch suitable for fitted garments like leggings.