[7/13/2006 After some thought on this post, I have made some changes and additions. The first time this was I left out a few things, and a couple of my drawings were not as meticulous as they should have been All new additions will be in color blue]
This post was prompted by a question posted over at Stitcher's Guild about how to alter patterns for broad shoulders. I started to answer there, but realized pretty quickly that my post was going to get tediously long, and thought I would work out my response here instead.
In this post I am just addressing broad shoulders, a fitting variance that I am well familiar with. I am not addressing broad backs, straight shoulders, or other variations on this theme. My shoulders are wider than the average pattern, and are wider than average for my size. This has always been a problem with patterns and purchased clothes. Of course I am also tall, and my shoulders are not out of proportion to my height.
The goal is to increase the width of the shoulders without altering the shape of the armscye and its corresponding sleeve head, and without altering the shape or size of the chest. If alterations are needed in these areas they are accomplished through a separate process.
First: Trace your pattern (it is always good to keep an unaltered master pattern in case sizes change or you mess up):
Second, cut out your newly traced garment.
Third: Draw in the actual stitching lines, if they are not already present on the pattern and/or you did not trace them. I always do this on my patterns as I tend to make several alterations, and it is the stitching lines, not the cutting lines, that show you the actual change in shape of the garment. On my permanent patterns I tend to save only the stitching lines, adding the size seam allowance I want for each piece of a garment. But this just works for me, there are many good arguments for keeping the seam allowance on the pattern as well.
Now we get into the fun part! There are several methods of actually altering the pattern at this point and I will describe the three methods I am familiar with. I am not an expert on any of these,and hope I understand them adequately and do not leave anything out.
PIVOT METHOD
I have several books that use this method, and this is the method I have most often seen Sandra Betzina use in her sewing seminars.
Remember the goal is to increase the shoulder without changing the armscye. To do this you start with something called the Pivot Point, which is, as I understand it the point around which the sleeve and shoulder will move with arm movement. I don't think I am describing it well. The pivot point is just above the notch and I have no idea how to determine it exactly, none of my books discuss this. On the lower part of the armscye below the notch, your arm doesn't move much. Try spinning your arm around. See all the motion is above the area of the notch, in the area that is typically eased in garment construction.
Lay your newly traced pattern on top of the original pattern.
Hold the patterns together at the pivot point, or pin it there. Now slide the new pattern piece out so that the shoulder seam gets longer, rotating the pattern so that the pivot point stays together but the armscye moves. I am increasing my shoulder widths by 3/4 inch, assuming that this person is 1 1/2 inches wider through the shoulders than the pattern allows. Carefully place another piece of paper on top of the two superimposed pattern pieces and trace the new armscye. Do not trace the rest of the pattern yet.
Notice that the the armscye is the same length, so you will not have trouble putting in your sleeve, but the position has changed slightly. I have traced over the original pattern in blue, very badly I might add, my photoshop drawing skills are minimal at best to show you the comparison.
You can now remove the first copy of the pattern piece you made, or
align it back up with the original pattern piece. Finish tracing the
new pattern piece, the one with the new armscye curve and the wider
shoulder. You will have to extend the shoulder from the original piece
and perhaps blend the shoulder and side seams a little bit to get them
to line up right.
You have now altered your pattern piece for a broader shoulder. Be sure to remember to use the same process and alter the corresponding back piece as well, making sure that the shoulder seams match when you are finished.
Added on 7/13/2006
You will notice that this method alters the width of the shoulder but also alters the bottom of the sleeve opening as well, making the garment a little smaller at the underarm. This is the first way I was taught to make this alteration. It actually does work for me because I often need to take up my garments in just that area, but this would not be true for every person.
Since learning this technique I have modified it. I make no claims that this modification is original; I am sure it is in books, it is just not the way I originally learned this technique. Angle the new pattern piece out from the original as shown above, anchoring the two pattern pieces together at the pivot point Trace the new upper armscye seam from shoulder to pivot point then trace the original pattern piece from the pivot point down to the side seams. If you want to check that this works try realigning your pattern pieces to see that they match.
Here is a picture of the new pattern piece, drawn by the alternative pivot method.
SLASH METHOD
I have really only used this method when I am altering a garment or muslin on the body, but I suppose it could be used for flat pattern adjustment as well. I am going to show the basic principle on a flat pattern as I don't happen to have a muslin to work with right now.
When you are fitting a garment on someone and the shoulder seam is to short, you proceed by cutting open the shoulder seam and then making an angled cut through the fabric down toward the pivot point of the arm.
You would cut the seam open, and then cut down the dotted line to the armscye.
If you were doing this on a person you would move upper portion of the armscye out until it was in the proper position and fill in the gap with extra fabric.
The end result would look something like this:
We are now going to do the same thing with our paper pattern:
Cut the pattern straight down from the shoulder. I usually cut from near the notch. You want a vertical cut that goes down to the level of the pivot point.
Next cut crosswise, from the vertical cut you just made to the stitching line at the pivot point.
Now you are going to move the outer pattern piece out until you have a 3/4 inch wide gap between the pieces. Carefully put pattern paper on top of your superimposed pattern pieces and trace a new pattern piece, blending in the angles of the shoulder seams to form a continuous line.
I had trouble photographing these steps so there is only one picture of the completed new pattern piece superimposed over the first two. I think you can see and understand the steps.
Remember to do the same thing to the back as well.
SEAM ALLOWANCE METHOD
This one is my favorite although I will use whatever method I need to at any given time to achieve the desired goals. I learned this quite a few years ago at a seminar taught by Judith Rasband, and it is used in her book Fabulous Fit .
Take your traced pattern piece and cut a diagonal line from the outer tip of the shoulder seam allowance down to the stitching line. Cut along the stitching line down to the pivot point. Cut the shoulder seam allowance off as well, leaving a bit attached along the neckline to provide a fixed point for reconfiguring the shoulder seam:
Your pattern will be in pieces. Angle the armscye shoulder seam allowance out 3/4 on an inch. Notice you will probably have to take a tuck in the seam allowance itself, but this will not alter the length of the actual stitching line. Match the outer corner of the shoulder seam allowance to the armscye at the stitching line (the inner corner of the seam allowance piece). Notice the shoulder piece is too short and might be angle up a bit. That is OK.
Your pattern pieces will look something like this:
Now, carefully place fresh pattern paper over this without disturbing the arrangement of the pieces and trace the new pattern piece.
In the following photo I have traced both the old and the new stitching lines so you can see the difference.
I like this method because I usually cut the seam allowances off my patterns anyway once I am done with the alterations. I like playing with them to make the alterations, and I find it easier to visualize what I am actually getting.
I am not sure it really matters which technique is used for making the alterations. Use the one that works best for you. The results are very similar, although not exactly the same, for each method as you can see from my three superimposed new pattern pieces pictured below:
7/13/2006 My original sketches were not particularly meticulous as I was in too much of a hurry to post this. Usually I spend a huge amount of time checking and rechecking my patterns when I am altering/redrafting them.
Since this has plagued me since the original post I have redone the drawings: As you can see, it really does not matter much which method you use. The three drawings line up almost perfectly on top of one another, as they should.
If you click on the picture you should be able to see a bigger view. All patterns are stacked on top of each other. The original blue is on the bottom. Then the three new patterns, slash in purple, seam allowance method in green, and pivot in pink. You can see best by looking at the dashed stitching lines on the pattern. Notice that the pink, (pivot method) does not exactly line up. No matter how hard I try I never get this to match perfectly, the armscye curve is always a little deeper into the shoulder, and I always lose a little bit at the side seam. But they are very similar.
The green and the pink are superimposed at the top, the pink and the orange at the bottom. I am sure the differences might prove significant for some people. We are all, after all, slightly different.