I am working on a reversible quilted jacket. I've been able to flat fell all the seams (shoulder, collar, and under sleeve) so far, but now I have reached setting the sleeve into the body. I have to turn under one of the flat felled seams as a fold over edge. Every other seam I was able to use the seam allowance that did not have a felled seam in it for the turned over edge. Do your books have any instructions on how to trim or turn a felled seam? Thanks for any help you can provide.I can share a few sources that I found helpful. These include what I consider my sewing bible the Reader's Digest Complete Guide to Sewing. I'll also share from the Singer Sewing Skills Reference Book and Great Sewn Clothes from Threads Magazine.
But before I do so, I will mention that there are flat fell seam foots. I personally sew on a Janome and for my machine I can sew flat fell seams using the top stitch foot and guide for my machine. I don't own these in my collection of presser foots. I found that I was able to achieve my flat fell seams without them. But I'm sure it could have made the task go easier. Other brands might refer to the foot used to make flat fell seams as a lap foot. Using a speciality foot suitable for your machine may prove helpful around those curved seams around the armhole.
The Singer Sewing Skills Reference Book suggests that
[t]he full seam allouwance is taken with the first stitching. The seam is pressed flatly as stitched, pressed open and then pressed with both seams together (20).That's a whole lot of pressing! It continues,
[t]he inside seam edge is blended to slightly less than the width of the finished seam, the upper seam edge is turned evenly and is top stitched (20).
The Singer Sewing Skills Reference Book did not specify at any point how much to trim, as you can see it didn't even suggest trimming one side of the seam. I did trim one side of my seams because of the weight of my fabric.
The Reader's Digest Complete Guide to Sewing does specify specific amounts to trim and goes into greater detail.
With wrong side of fabric together, stitch on the seamline. Press seam open, then to one side. Trim the inner seam allowance to 1/8". Press under the edge of outer seam allowance 1/4". Stitch this folded edge to the garment. Be careful to press like seams in the same direction (150).This was the trimming amount that I used for the Vogue 1263 jacket and that was also recommended in my copy of Vogue Sewing. The Vogue pattern instructions for the Donna Karan design jacket, Vogue 1263, suggested that I trim the seam allowance to 1/4" but they also instruct that you stitch right sides together. Whether you stitch with right or wrong sides together depends on if you are trying to create an inside or outside flat fell seam.
Great Sewn Clothes contains instructions for sewing flat-fell seams using a felling foot.
With right sides together, wider allowance folded over narrower, make a few stitches with foot on top. Stop with needle down, and raise foot. Lift fooled edge over blade. Finish seam. Open seam and press flat. Stitch second row same as first. Underside looks like welt seam (106).I'm not sure I would like to use this method for the armhole but I do like the thought of using a felling foot for this area to keep the width even and just adapting instructions with the trimming and press steps mention in the previous sources that I quoted from.
Carla, I hope this helps. If anything I discovered while sewing Vogue 1263 and flat fell seams is that there are many ways to achieve a professionally looking flat fell seam. Good luck and I hope this post helps. I would love to hear how it turns out for you.
Colton, Virginia, ed. Reader's Digest Complete Guide to Sewing. New York, The Reader's Digest Association Inc., 1978. Print.
Singer Sewing Machine Company. Singer Sewing Skills Reference Book. U.S.A, The Singer Manufacturing Co., 1955. Print.
Threads Magazine. Great Sewn Clothes. Newtown, Tauton Publications, 1991. Print.