Set - In Sleeve

This is the fourth post on types of sleeves preceded by kimono, dolman, and dropped sleeves.

Usually "set-in" refers to the traditional, high-fitting sleeve. The shoulder/sleeve seam sits right at the crest of the wearer's shoulder socket. The sleeve must be cut with a high cap and enough ease to provide an attractive curve over the deltoid.

Maximum freedom of movement for the arm (without disturbance of the rest of the garment, that is) is achieved when the base of the armhole is high under the arm. Note that if you own close fitting t-shirts or active wear, they all have high armholes and sleeves with deep caps.

There are several things to be aware of when dealing with set-in sleeves.

• They can be inserted "in the round" or "flat."

For the former, left, the underarm seams of body and sleeve are completed first, and the tubular sleeve is sewn into the resulting "hole" in the bodice.

Flat insertion, right, is done mainly in industry or very casual clothes. The sleeve is sewn into the armhole before the body's side seam and the sleeve underarm seam are sewn. So, the garment is "flat" when the sleeve is attached. Then, the underarm seam is sewn from wrist all the way to the garment body hem.

• Set-in sleeves are not symmetrical. What I mean is that there is a definite front, and back, to the sleeve.

Think of sleeves as hands. If you have fitted leather gloves you have only one way to put them on. They are not interchangeable. Set-in sleeves are the same. There is a right and a left sleeve. They are mirror images, not super-imposable.

Often students will mistakenly cut two right or two left sleeves. Remember you need one of each. If hands were sleeves and the backs of your hands the right sides of the fabric and the palms the wrong sides of fabric, the only way you can lay them together is in mirror image, in prayer position. Sleeves have this same property.

The reason that sleeves are asymmetrical is because the front of the sleeve is shaped differently than the back.

Think about your arm now. It's definitely not the same in the front as in the back. The arm is tilted forward at the shoulder. Also, it is more concave in the front, convex in the back. The sleeve needs more coverage in the back, less in the front. That is reflected in the sleeve cap pattern - there is more fabric (width and length) in the back of the cap.
Front and back armholes are not the same either. The front of your chest is sort of hollowed out, concave, where it meets the arm. At the same level on your back, your body is full and convex. So...the armhole is more scooped in the front, and is flatter and longer in back to accommodate the outward curve there.

• Conventionally on American patterns there is one notch on the front sleeve cap and two on the back. There is a dot at the point where the top of the cap meets the shoulder seam.

• There are also smaller dots between which the sleeve is meant to be eased. I almost always find it better to just ease the sleeve all along the sides of the cap. You can get more ease in this way and it looks smoother.

Here, the wobbly line indicates where I usually ease the sleeve, rather than between the two small dots.

There are several ways to ease in a set-in sleeve. I almost always just stitch around just outside the seam line of the cap with a larger than normal stitch length and maybe slightly tighter tension. I do this before or after I sew the underarm seam, it doesn't matter. And because I am sewing through only one layer of fabric, the tension of the stitching causes the fabric to draw up a bit. Which is exactly what you want. But more on easing sleeve caps in a future post.

• Some set-in sleeves on very fitted dresses have elbow darts. It is also very common in fitted jackets for sleeves to be cut in two pieces (remember, seams can act as darts) to achieve shaping.

• There are a jillion style variations on the set-in sleeve. And you will find an excellent discussion of these (with much better illustrations) here: Modern Pattern Design. Be sure to scroll down far enough to see all the types of sleeves.
  

In fact, this entire book is available here along with other sewing books that are past copyright protection. VintageSewing.info Definitely worth checking out.

Next time - Raglan sleeves. The heck with physics.