At all openings that will hug the body, (ie the leg openings) I use swimwear elastic to help the fabric maintain its elasticity. In the picture located in the supplies section, I am stitching elastic to the upper bodice of the swimsuit. Instead of measuring a piece of elastic, cutting it and pinning it in place, I simply serge the elastic onto the wrong side of the seam allowance, keeping an even tension on the elastic.
When I get to the end of the stitching, I serge off the edge of the elastic and trim the elastic to size. I find it easier to maintain a consistent tension on the elastic if I am not working with a smaller piece which is why I prefer to cut the elastic off the roll after stitching it on. One thing to remember is that the elastic isn't meant to be tight or squeezing the body, but to simply hug it so there's no need to pull the elastic much while stitching. The stretch should be in the FABRIC and the elastic will just be there as a helping hand to keep everything snug and in place once the fabric is wet or been worn for awhile.
Here is what the upper bodice looks like after stitching the elastic to the edge. (I was assembly line sewing a few suits for my girl so the fabric will change periodically in this post.) You'll notice that there aren't any puckers in the fabric which means the elastic has just the right amount of tension. Trim away the excess elastic from the ends.
Now we're getting to the fun part. Turn the elastic down to the wrong side and either pin or finger press it in place. Again, I don't bother with pins for this part as I find it's easier for me to control the tension in the elastic without having to start and stop for pin removal.
Insert the turned over seam right side up (the outside of the swimsuit) underneath the presser foot of the CoverPro.
Remember that with the coverstitch you need to start your stitching on the fabric and not off it like with some regular machines and sergers. Begin stitching along the edge, using the edge of the presser foot as a guide. Continue to maintain the tension on the elastic while making sure it is folded under right along the edge. Stitch all the way across.
Again, remember that you'll need to end your stitching on the fabric and not off the edge (though the picture above looks like it was off, I assure you it wasn't) and raise the needles to their highest position.
Lift the presser foot and using tweezers or some thin implement; pull the needle threads from under the presser foot above the fabric out toward you.
Snip the two needle threads.
Pull the fabric back behind the presser foot which will pull all three threads to the underside of the seam.
I prefer to make a small knot with the three threads on the wrong side of the fabric, just to ensure they won't be pulled out with wear and tear. Once knotted, I run the threads through a needle and hide a bit of a tail in the seam for extra precaution. All of the edges with elastic should be completed this same way - securing the elastic to the wrong side first (serging works best), turning the elastic over and coverstitching the elastic in place.
Occasionally, you'll reach a thicker section like a seam or where the straps are attached and I've found that the Seam Tightening System inherent in the CoverPro 1000CPX is perfect for this case. Stitch the regular part of the seam with the light-weight setting on the front of the machine (the picture of the camisole with the switch toward the right) and stitch to the right before getting to the thicker section.
Push the switch toward the left for the thicker section which will adjust the tension of the stitches. Stitch over the thick section and when you get back to the regular thickness, pause and push the switch back to the right. Continue stitching the rest of the seam per normal.
Another place I love to use the CoverPro is for the straps as I know it'll help keep things secure for all the wear and tear that will be put on a swimsuit.
Start by lining up the circle of strap fabric right side together with the swimsuit and serge elastic to the edge through the two layers of fabric. You'll see that the elastic is stitched to the wrong side of the strap fabric in this case, but it will be on the right side of the main swimsuit.
Turn the swimsuit right side out, pushing up the strap fabric over the elastic.
This it what it will look like from the inside. You'll be covering up that stitching with the strap fabric in the next step.
Now continue to fold the strap fabric over to the wrong side so it covers the elastic completely.
Again, this is what it will look like from the inside of the swimsuit. Don't worry about there being extra fabric as it will be trimmed off later.
Coverstitch from the right side of the swimsuit through the wrapped around strap fabric, sandwiching the elastic and main swimsuit seam. You can see in the picture above that I don't bother pinning this step either. I simply wrap the fabric around as a stitch.
When coverstitching a circular seam, I like to pause when the starting stitches make their way around to pull the needle threads through to the underside.
Knot those threads together, leaving a tail. I find it's easier to do this before stitching completely around the circle and potentially over those starting threads. After knotting, continue to stitch around the strap, using the method described earlier to pull the ending threads to the wrong side as well.
Thread the knotted threads through a needle and hide the tails in the seam.
Look at how nice that strap looks! Trim the excess strap fabric from the wrong side so it won't be seen once worn. Swimsuit fabric won't fray easily so trimming like this works well.
See how nice all of those seams look? I made a size larger for my girl since I'm hoping to get at least a year's worth of wear out of it and she's at an age where she's growing super fast!
As you can see, she loves her swimsuit and I hope you'll use some of these tips to dive into your own swimsuit sewing adventures.