Drafting custom sewing patterns

Let’s take a look at the drafting patterns to the individual measurements.

I have two books on this subject – one I have bought in a Russian bookstore when I visited with my friends in Chicago, and the other one is “Finally It Fits”, by Ruth Amiel and Happy Gerhard, published in the US first time in 1973. I have 1976 edition, it is out of print. The Russian book was published in the Soviet Union in 1988, it is a kind of a textbook for middle school home economics class and is very close to what I have been taught in school, but much less than what I had when I took pattern drafting and sewing classes. Both books describe the pattern drafting process in very similar terms, and arrive to very similar results. My personal experience is that these directions for drafting the custom pattern are very good. If measurements were taken accurately, very little corrections are needed during fitting.

The measurements used are a little different. In Russian book to arrive to the armhole depth an elastic tape is put around the neck from behind, then the tape goes to the underarms on front and then around the back at the lowest points of the shoulder blades. To determine the armhole depth you measure from the highest point of the neck where neck connects with the shoulder down the back to the level of the elastic tape. 

In American book they measure from the waist to the armpit on the place of the side seam.

Then the pattern for the very basic sheath dress is drafted. First pattern for the back is built, then for the front. It looks like this, with the skirt front and back overlapping, so we can draw the armhole as one curve:

The side seam is moved toward the back, but it may be positioned at the middle of the armhole. 

Next the pattern for the sleeve is drafted. For the sleeve we need to determine the height of the sleeve cap.

First, let’s see the instructions in the Russian book. We are instructed to connect the shoulder points of the pattern with a straight line; then divide this line in half and square down to the armhole depth line. This is the pattern armhole depth, Measure it on the pattern. The sleeve cap height is armhole depth minus 2.5 cm (1 in). 

 In the “Finally It Fits” book we are instructed to square down from the back shoulder point to the armhole depth line and measure this distance on the pattern. Then square down from the front shoulder point to the armhole depth line and measure this distance. Then calculate the sleeve cap height: add together front and back armhole measurements of the  pattern, subtract 2 inches and divide the result by two.  

The Russian way:

The American way:

 

Essentially both methods are the same – the average of the front and back armhole depth minus 1 inch. In Russian way we calculate the average by means of geometry; in American way we arrive to the average by means of arithmetic: (ab+cd-2):2=(ab + cd):2 -1”.  

If we apply this reasoning to the simplified knitting diagram we get the sleeve cap height to be the armhole depth minus 1 inch. Since these are directions for the woven fabric, the ease to sew the sleeve cap into armhole is taken into consideration. For hand-knit garments we don’t need ease, we can make the height of the sleeve cap less and estimate it at armhole depth minus 1½ - 2 inches. And this is what I have been always doing.  And I didn’t have any problems with the fit of my hand-knit sleeves.

The standing question remains – Where 3" difference between armhole depth and sleeve cap height comes from? 

I keep asking this question on an assumption that ready-to-wear patterns are drafted basically in the same way as custom patterns, but to the statistically average sets of measurements. So they have to arrive to the same, or very similar, results.