It is often said that set-in sleeves are the best fitting type of sleeve. That's probably why T-shirts and polo shirts are constructed with set-in sleeves. A set-in sleeve sweater will not have the extra fabric at the underarm like you get with drop shoulder and modified drop shoulder sleeves and also in yoked sweaters.
So let's take a look at how a sweater is is constructed with set-in sleeves. The traditional way is to knit four flat pieces of fabric, namely the front, the back, and two sleeves. These pieces are then seamed together.
And that is the first problem. You may or may not be very good at seaming straight edges up the sides of the body and up the length of the sleeve. But then you get to that place where you have to fit the sleeve into the hole left in the body. This is considered the most error-prone seam in knitting. Many times it takes more that one try to get it right. How frustrating it is to get the seam finished and then realize it is stretched in some areas and puckered in others! So you tediously take out the seam and try again.
But that's not the only problem with this construction. What if you have a pattern that is very difficult to work on the wrong side. Some people have a lot of trouble working Fair Isle in alternating right-side and wrong-side rows, for instance. Or perhaps you want to use a complex Alpine style pattern, which unlike most Aran patterns, works cross-overs on every row. It can be very confusing to get the cross-overs in the right direction when working on the wrong side. Or maybe you just hate to purl and now half the sweater in Stockinette Stitch has to be purled. For any of these reasons and perhaps a few more, knitters may want to do as much of the sweater as possible in the round.
It is possible to modify the traditional approach by working the lower body in the round (and maybe also the sleeve. But everything above the underarm still needs to be worked flat since the sleeve is knitted separately. And you still have that pesky shoulder seam to sew.
If you Google the phrase 'seamless set-in sleeves' you will find a number of books and articles. Most of them will suggest a top-down approach that works something like this. The top of the sweater is worked flat from the shoulder to the underarm, leaving shoulder holes as usual. Then the lower body is completed in the round. Finally you pick up stitches around the armhole in the body. But you can't just start knitting in the round because the sleeve needs to be given a shoulder. So you then have to work a number of short-rows, working flat, back and forth, until you finally get to the point that you can finish the sleeve in the round. Look how much of the sweater is still worked flat, even though now don't have any seams to work.
With that construction, it is still difficult to work complex patterns above the underarms where you have to alternate right side and wrong side rows. It can also be difficult to work the shoulder area if you want to have a complex pattern there as well.
So I have developed a method and enhanced it over the past year to construct a sweater with set-in sleeves that is seamless and is done almost entirely in the round. Of course nothing is really new in the thousand year old craft of knitting so I am sure this has been done somewhere or some time before. In fact, the general idea was suggested by Barbara Walker in her book Knitting from the Top. But her suggestion did not produce a sleeve cap that is bell-shaped as would properly fit the shoulder. See the sleeve cap in the traditional sweater construction above? It is shaped like a bell. Not like a witch's hat with a flat brim, two flat sloped sides, and a flat top, as JC Briar pointed out in her class on set-in sleeves.
What I developed was a computer algorithm to use properly spaced increases down the sides of the cap to generate a five-sectioned curve that closely resembles a bell-shape that perfectly fills the sleeve hole with the proper depth and recess to replicate the traditional set-in sleeve construction. An early version of this algorithm was published in an article in TKGA's Cast On magazine in the Fall, 2018, issue. By all means, you should subscribe to that magazine for only $25 per year and not only get every new issue that comes out, but also access online to their entire archive of issues, including the one with that article.
Take a look at the construction of a sweater using Phrancko's Seamless Set-in Sleeves:
I have published a pattern using this technique in every issue of Cast On magazine since the Summer, 2018, issue. An article I wrote specifically describing an early version of the algorithm appeared in the Fall, 2018, issue. In the next blog entry, we will take a look at those patterns to see what you can do with Phrancko's Seamless Set-in Sleeves that is more difficult with other means of construction.
Once I realized the algorithm would work for almost every realistic sweater size and knitting gauge, the idea occurred to me to create Phrancko.com to create custom-fit sweater patterns using the technique. Even though the sweater pattern is for a plain sweater, you will see in the next entry how the pattern can be modified to create all kinds of sweaters that would be difficult in any other type of set-in sleeve construction.