How to create grade rules 3
For the previous entries in this series, see here, here, here, here and here. Reminder: for purposes of explanation in the exercise of deriving grade rules, we’re using the CS151-50 (opensource). I’ve linked to it enough times in the previous entries so you should have it by now. And finally, we’re cribbing off the spreadsheet (in the forum) of needed grading changes from the CS151-50 to do the actual portion of this work.
Continuing from the girth rules done Tuesday, the lengths are easier. But first I want to show you something because now you have to keep track of grading notation. I don’t know how many have seen this. If you have my book, go to the grading section “how to map a pattern” pp 173 on. Otherwise, this will be familiar to old-school pattern makers. I don’t know how many people still do this today. I still do. Below is a pattern that is mapped with the measures derived in the girth exercise.
This manual pattern based system shows each point with crosses indicating the amount of grow at that point. The crosses indicate x/y coordinates. You’d shift the points the indicated amount using a grading ruler or grading machine. You can even use a 2×18 ruler for this.
Question: Those of you familiar with this system, how did you learn it? I learned it on the job but never found it in any books (a vast oversight in my opinion which is why I included it in mine). Later, I found similar guidance in the instructions that came with the Dario-grade-o-meter but I’ve since misplaced it. Anyone still have a copy of that lying around?
Anyway, there’s three -no four- basic ways to track and store your notation. I prefer to make notation right at the grow points on the pattern piece as I go along if I’m doing it manually. CAD systems do it differently. In OptiTex, you do it “on the fly”; it’s pretty cool how it works. Until I get good with the software, I plan to keep the grading notation on the hard copy for reference. Here’s a screenshot using the software. The grade (girth only) of point 2 (shoulder/neckline) is shown.
Another way to keep track of your grading points is in PLM/PDM software. I’m kicking the tires on StyleFile (won’t launch till 4/15) but I can’t figure out where to input that right now. The last way to do it is with a spreadsheet or a manual paper system.
Returning to the deriving the length rules from the CS151-50 sizing chart (cheatsheet in the forum) here’s a screen of the lengthwise size differences from which we’ll get the rules:
Right away, you’ll notice that the length differences are much more dramatic than the girth differences, especially when compared with adults. Kids are getting taller than they are wider. You may also notice that the rate of grow varies. As any parent can tell you, kids shoot up and then taper off. They’re still getting taller but not at the same rate as before.
Scye depth is first. This shows the armhole getting longer 1/4″ per size until size 6X which is kind of a half size of a still larger size (last size before the size break and you have to use a different pattern entirely for 7-14).
Shoulder and arm length. Nobody said grading was an exact science and I’m about to prove it. Remember Tuesday when I said that shoulder length was included in girth because it was a horizontal measure? Well, at that point we’d decided to use 1/8″ (half of the quarter of the total chest girth grade). Go back and look if you don’t remember. Today’s chart is showing a range of sizing differences of 1.5″ to 1″ (again, rate of grow tapers off in the larger sizes). Technically, you’d subtract what you’d added to the previous shoulder grade from this total measure, to figure out how much longer you’d make the sleeve in each size. I guess this is included in vertical (length) grades because the arm hangs down.
Cervicale to the waist. In adults, this is about two heads (2/8 of total height) long. This chart shows the CB waist lengthening by 1/2″ per size which is a pretty dramatic difference. In adults, it’s half that, about 1/4″ per size.
Waist height we can skip for now. In a previous entry, I’d described this measure as from the floor up to the waist so it won’t be useful for grading purposes for a bodice -what we’re still working on. It’s useful for pants though.
Waist to hip is useful and listed as 3/8″ per size. Still, this strikes me as too much. The reason is, the waist to hip equals a little bit less than another head, so you’d add half the CB grow (2 heads) measure to grow down from waist to hip (for tops). At least for adults. Following that rule of thumb -even for kids- it’d only be 1/4″.
Next time I’ll have to remember to add up all of those lengthwise grows and see how they match up to the reported total height increases for each size. I also have to create another pattern showing all the final notation because the piece I’m using as an example, doesn’t go past the waist.
I bet by now you really understand why folks tend to keep a lid on their grading, huh. I don’t expect you to believe this but it’s a lot easier than it sounds. And, I’d agree with the suggestion that a video would be helpful. It also wouldn’t hurt to get a grading book. This series is only intended to explain how one derives grade rules from sizing charts.