Tutorial - Flat-felled seam

I’ve seen many flat-felled seam tutorials around the web, but sadly not one of them mimics industrial flat-felled seam.

When you look at the flat-felled seams on your store bought jeans you see two rows of stitches on both right and left side; cutting edges have been nicely tucked between two details on the outside and on the inside and the back center is right between those two rows of stitches.

And here is how you can do same looking flat-felled seam at home on your commercial sewing machine.

Step 1: Adding seam allowance before cutting

First you need to figure out how wide you want your flat-felled seam to be and how wide apart the two rows of stitches are going to be. I figured I will mimic the inseam on my favourite pair of jeans where the stitch rows are about 0,7 cm apart.

So you will multiply the width of your two seam rows by two.

I got 1,4 cm and decided to add 1,5 cm of seam allowance. (Really, 1 mm is not that big of a loss)

Step 2: Cutting and ironing

Now that you have added the seam allowance you are ready to cut your pieces out.
After cutting, you will iron back 1 cm of your seam allowance as follows: on one piece, lets say seat seam, on to the right side of the fabric, on the other piece to the left side of the fabric.

Step 3: Folding your seam allowances into each other and pinning the pieces

Step 4: Sewing

Now sew your pieces together from the right side making the first seam about 0,1 cm from the folded edge and the second one around 0,7 cm from the first seam.

Flat felled seam from the right side

and from the left side

Option Two:

Step 1 - add seam allowances as mentioned before

Step 2 - mark 1 cm on one piece from the cutting edge

Step 3 - place second piece on top of the first one, so that the cutting edge of the second piece is aligned with marks on the first one. 

Pin those two together and sew as shown below.

Step 4 - Fold the seam as shown below, baste if needed and iron it gently.

Step 5 - sew from the right side, making the first seam 0,1 cm from the folded edge and the second one about 0,7 cm from the first one.