For someone who’s always touting one should keep an open mind -keeping their indoctrination at arm’s length- I have a lot to learn. I truly believed the nest quiz (pt one, two) questions were obvious at a glance. Other than the match stripe of course, not every one has worked with those and I was pleased that Todd correctly stated the grader was attempting to simplify the nest by lining everything up there. I don’t think the given grader was used to match stripes either. Maybe that was the crux of the problem.
Now I’m going to explain why the baseline lies at the AH (armhole) line, it is for reasons beyond traditional standard practice. First though, I’m going to show with some scans I did this morning, that all of the books show that line as the baseline. It is ubiquitous. By the way, if you don’t have a grading book, it might be time to buy one. I’m genuinely perplexed this appears to be so confusing because grading is much easier (and much less expensive) than pattern making.
Handford’s grading book (my preferred text) illustrates below:
An accompanying nest from the same text (below):
The Fairchild book (which I don’t like as well) shows the baseline to be slightly higher than Handford but this difference is immaterial (below). Fairchild has emphasized the point by describing this as the “cross control line”.
The Cooklin book (which I also like but is not shown) shows it slightly higher (in the armhole itself) than both Handford and Fairchild but again, this doesn’t matter. The actual movements either up or down, take place north and south of these baselines. These are all correct.
Not to go off topic, but all garments have a baseline. As the trouser scan from Cooklin (below) shows, the zero point for pants is at the fork.
Lastly, it is immaterial for whom the product is intended. Below is a scan of a child’s top, again from Handford.
Summary: All of the pattern and grading books show this AH line to be the baseline of grading between the upper and lower portions of the garment. The reason it is also the stack point of a nested grade, is so that it is easier to check the accuracy of the grade. If your pattern is growing both up and down from that point, it is much easier to see problems. Even home sewing patterns use this as the stack point of graded patterns.
The reason you can’t stack from the CF/CB neck point is that the body grows in two places north of the AH baseline. It grows up (or down) from the shoulder and midway through the armhole. If you stack on the AH baseline, it’s easier to check both in one glance. If you stack at the CF point, you can only check the upward shoulder growth at a glance. To check the growth midway through the armhole, you have to measure -and because this affects total garment growth at the bottom, you have to subtract the difference from the total length at the hem. That’s a lot more math and measuring. If you stack at the AH baseline, there’s no measuring and no subtracting because it’s (in my opinion) obvious.
Besides, if the AH baseline is the dividing line between growing up and down, isn’t it logical to stack the nest on that line? I don’t understand why one would stack the nest at a point (CF neckline) that moves.
Returning to the original polo nests, here is a side by side comparison of the two. Nest #2 is to the left, nest 1 on the right.
As it happens, the two nests looked so different from each other that judging from comments, people thought these were two different pattern sets and/or two different grades! How can one check accuracy of a grade if people think they’re looking at two completely different patterns? While the patterns of each were technically correct, the grades were not. Stacking nest #1 at the CF neckline, obscured the faulty grading. The proof was in the pudding; once I explained why the grade was wrong, it was much easier to see the faulty grade in nest #2 than in nest #1. You could do see that on screen. In real life, you’d need a ruler and some math.
In summary, error prevention is the reason why the AH line is the zero or stack point for a graded nest. Also see the step by step process of grading illustrated in my book, pages 170-175, complete with exploded views involved with mapping a pattern, preparing it for grading.
Related: In entry 2, JC remarked:
I was instructed to pick a stable point (i.e. least amount of movement or distortion) of the body – like: C7, sternal notch, or sacrum – and emanate the graded pattern off that point.
Is it possible you were instructed to draft (not grade) from that point? An archaic practice, particularly in MTM tailoring, was to draft from C7. If you review page 164 of my book, you already know the value I see in that. In drafting, the sternal notch or C7 doesn’t move. Personally, I wonder if that baseline of AH was established because it marks the center of gravity of men and as most of us know, it was men’s apparel that was refined for mass production first, establishing precedent.