This is an example to show what we are trying to achieve with the steps relating to Figure 3 of the Sleeve Instructions.
In this example, the front and back armhole measurements are significantly different: front = 9.38-inches, back = 10.31-inches.
- The shape drawn in red shows the sleeve that is created using the symmetrical method.
- The shape drawn in black shows the sleeve that is created distributing the back and front armhole measurements separately.
The two shapes are lined up at the mid-shoulder point. You should see that the sleeve with the correct distribution (according to the armhole measurements), is larger in the back and smaller in the front.
The usual 'fix'
If you used the symmetrical sleeve as is, there would be more ease in the front of the sleeve than in the back. To solve this issue, some block making instructions direct you to 'walk' the front and back armholes from the underarm point and mark where each ends. The mid-point of the excess is then marked as the shoulder point. i.e. The end result is that the shoulder point is just moved forward.
However, the shape of the sleeve created using this 'fix' is different (and not as good as) creating the curve around the correctly distributed measurements. (See Image 3C).
The symmetrical sleeve has had the mid-shoulder line moved forward, and now not only the mid-shoulder points are lining up, but it can also be lined up at the bicep line.
The symmetrical sleeve has a different shape to the sleeve created based on the actual distribution of the armhole measurements either side of the shoulder point.