I decided to create a separate entry rather than respond to the first entry in comments because some people don’t read those. If that describes you, half the valuable content on this site is in comments.
I have been measuring each seam – carefully! – notch to notch, with a tape measure on its side. Why do you recommend walking the seams rather than measuring? What have I been missing out on by doing it this way?
When we say to “walk a pattern” we mean to check it. It doesn’t exactly mean walking pattern piece seam lines together but is a combination of various methods. In fact, I don’t walk patterns in CAD at all, I measure the lines and compare the lengths. There is no reason you can’t measure seam lines if you’re checking manually. One caveat; tape measures aren’t the best tool for this. I recommend a 2×18 B-95 ruler instead. Tapes can stretch so calibrating them is required. There is also a section of this video where I show how to walk with a ruler so I’ll have to dig that out too.
Mia mentions a long standing problem, that of oak tag pattern paper curling so much you need to iron it. This is surely annoying. The way I deal with it is as Sarah_H says: when I get a new roll, I cut it into >48″ long sheets and store them flat and covered. You can also buy flat sheets but the cost is prohibitive, on the order of three to five times more than rolls.
Ann K asks:
why a 3/8″ seam allowance rather than 1/2″? Would side and armscye seams also be 3/8″ then?
The type of material, desired seam type and seam location governs seam allowance width. Since this seam was a single needle butterflied (SSa-1), and on the interior of the garment, it takes 3/8″.
To the second part of your question, the shoulder seam doesn’t rely on another seam’s width, each seam is determined independently. If the other seams are sewn just like the shoulder, they would be the same (3/8″). However, if the side seam is safety-stitched, it would be 1/2″. If the armhole didn’t have a sleeve at all but just a facing and was single needled, it would only be 1/4″. The allowances of the side seam and armhole have nothing to do with the shoulder seam of this style. See The rules on seam allowances and pt.2 for more.
What happens to the seam allowance after this point? I was my understanding that the seam allowance had to match so that cut pieces matched exactly. How do you handle that? I usually end up making a new front pattern so I can add half the back seam allowane that is too big to the front and cut half of the excess off the back.
I’m not sure I understand your question so please clarify. As I interpret this, it doesn’t hold that the two cut fabric edges should match in length. If they did, you couldn’t sew convex and concave curves together. The only thing that matters is that the seam line lengths match. The way seam allowances should match is explained in the production pattern making section of my book.
Lisa Blank said:
It was interesting to me to see that you took the difference off the back rather than splitting the difference between front and back.
You saw the shortcut. It doesn’t necessarily mean you would always shorten one side as I did in this video, favoring the shorter side. It really depends on the seam shaping. You need to overlap the pieces so you can see the neckline shape (as in this case) to see if the back should be shortened, the front lengthened or divvied up between the two. What isn’t obvious in this video is that I deliberately created errors in the pattern beforehand so I knew which ones to correct. I designed errors to make examples of the most common kinds of changes that people need to make.
I always walk my patterns instead of measuring. When I walk, I imagine what the seamstress will be doing, in the correct sewing order. I check notches, pattern shapes when they are connected, to be sure that they are accurate for the seamstress. Measuring will not achieve the same result that walking off does. Talk to a seamstress. She will tell you.
A hallmark of a well designed pattern is keeping sewing order in mind. That said, one can only control for so much due to various types of handling between operators. I think it is better to hit a point of exact lengths (however it is you get there) and use that as the litmus test and have individual operators adjust to it than vice versa. The alternative just isn’t possible; you can’t make patterns for individual stitchers. If an operator is missing the mark, they probably need more training with respect to handling. The other reason I think this is important is because one’s machine may be mis-feeding and needs adjusting.