Adjusting the Basic Conic Block for an Athletic Shoulder or Curved Back

I’ve been doing some background work for a project, and I had to do up a Conic Block for Lizzle. Her body is a leeeetle bit stylized, and she’s particularly got a relatively wide shoulder and upper back (like a swimmer), and she has a distinct curve at her upper back (a swimmer who spends too much time hunched over a desk, maybe?). Anyway, here’s an adjustment to the Basic Conic Block draft for situations where the upper back is significantly larger than the back bust measurement.

You will need the following measurements:
  1. Bust, Front/Back Bust
  2. Front/Back Shoulder to Shoulder Width

Most of the time, your Back Bust is larger than your Back Shoulder->Shoulder measurement. That’s because the bust measurement is taken around the curve of the body, whereas the Shoulder->Shoulder measurement is (usually) pretty much flat. If Lizzle were human size, her back shoulder->shoulder would be 2 1/2″ larger than her back bust measurement. I realized I was in some trouble when I started drawing in straps and the back strap was inside the armscye. If you find yourself in this situation, here’s how to modify the block.

(Note: for this demo, I went ahead and drafted the block with the back strap about 1/8″ to the back of the side line. I am modifying the back of the block form there. If you’re drafting, you can make this alteration as you draft the back. I am working on a new printer-friendly version of the directions!)

Here’s the problem:

problem caused by wide upper back

When I line up the block on Lizzle, it meets her center back at the waist, but angles away by the shoulder.

I’m using half the block for visual clarity. If you’re using a full block, this problem will manifest itself by making the entire block sit at an upwards angle on the body, and there’s really no chance of it meeting at Center Front. If you see the waist/bust lines drifting visually upwards, and your Back Shoulder->Shoulder is the same as, or larger than, your Back Bust, then this is probably what’s happening.

If your block is already made up: slit it down the back. You can either re-draft with the following steps, or cheat. To cheat, you’ll need a partner in crime, or some major double-jointed-goodness, some more poster board, two brads, a marker, and tape. Ready? Cut down the new sheet of posterboard so that it is no wider than the existing back of your corset, and about two inches taller. Draw a vertical line up the middle. Use the brads to attach the waists of the back pieces to the posterboard, at the vertical line. (You’re using brads so that the pieces can pivot and be adjusted easily.) Put the block on, and tape the front shut. Your cohort should be behind you, and can adjust the pieces of the block against the new piece of posterboard to make an even rectangular insert. Tape the backs in place so the tops are the same distance from that center line. Remove the block. You’ve now got the extra triangle you need in the back.

Now, here’s the draft modification:

unfolded block

Take your draft, and unfold all the foldies (side back, side, and side front).

block cut up side line

Cut the block up the true (vertical) side line. We'll only be working with the back, so set the front aside for later.

the basic grid

Draw your basic Side/Bust/Waist grid, using your Bust->Waist length, as you did to start the Block.

If you are currently crafting your block, start at the following point:

redrawing the back using the shoulder measurement

From the Side line, measure out 1/2 the Back Shoulder->Shoulder distance. Draw a vertical line here. Draw a second vertical line at 1/2 that distance from the Side Line.

I’ve got my original back lined up on the half-point of the back draft, so you can see what’s changing.

location of the fullness of the shoulder

Now, the fullness of the shoulder is really up higher than the Bust line - closer to the neck. I've sighted about where it is by looking at my doll. You could measure if you're feeling scientific.... ;)

finding the back width at the bust line

If you connect the widest point of the shoulder (along the center back line) with a point that is 1/2 the Back Bust away from the back midline (ie, the normal back width of the block), you will have about the width of the back at the Bust Line. Mark a tick on the Bust Line, then one on the waist line DIRECTLY below the bust mark.

marking points from the side back

From the midline of the back (in this case, the ticks half way between the back and side lines), mark a tick close to the sideline that is the same distance from the midline as the tick from the last step.

Quadruple the measurement you used to mark that tick. This is your new Adjusted Back Bust.

Basically, all of your geometry is now based off of the adjusted Back bust. This is going to change the size of the back and side-back triangles, and create more curve in the finished block. These additional curves will specifically be in back, and will help mimic the effects of your wider upper-torso. It sounds a little goofy, because we both know you took your Back Bust measurement correctly (and probably repeatedly, if things are going wrong), but geometrically it’s sound….

I’ve traced off the back strap, because I had it. If you’re drawing it later in the draft, you should start it at about ((1/2 Adjusted Back Bust) – 2″) in from your side line instead of using the shoulder->shoulder measurement.  If you have a wider upper arm, you might need to subtract more than 2″ from the bust measurement. You will angle the strap at the midway point during the fitting to get it to hit the right place on your shoulder.

finishing the back

Connect the outermost ticks to make the new Center Back line. At either side of the midline, and to the inside side-back tick on the waistline, measure 1/6 of your (Adjusted Back Bust - Back Waist) and mark.

comparing the two back drafts

Mark in the normal triangles around the back midline and the back side of the side line. This results in a different back draft than you got with the original directions.

Now, if you’re paying close attention, you’ve probably noticed something that escaped me until I went to fit the block again: 1) I connected to the wrong side tick on the waistline. I meant to use the inner one, which has the adjustments in it. I still do these things….  Le sigh…. At least it’s easier to take paper out than to put more in. ;)

test-fit of the new back

I cut the back out, folded out the triangles, and checked it against the doll. It's lined up with her Center Back seam...

fit-check at side

And wonder of wonders, it hits her side seam! Yay! Mischief managed!

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