19 August 2014

Converting Big Honkin' Darts Into Shoulder Princess Seams (long & pic heavy post)

Anyone of ample boob size who's had to make an FBA dreads the inevitable BIG HONKIN' DART (haha thanks Debbie) that results; well, at least I do.  I make anywhere between a 1 and 2" FBA just to get the centers front almost close.  The result of this adjustment is usually a large dart that is next to impossible to sew or keep neat.  I got so frustrated with the BHD that I stopped buying patterns that had darted fronts. 

Having had recent success with fitting shoulder princess seams and converting back bodice darts to princess seams, I decided to attempt to do the same with the front.

I'm going to describe how I got New Look 6407 to fit reasonably well by doing an FBA, tackling the big honkin' dart, and changing the front and back to have shoulder princess seams.

The pictures below are my second attempt at the process and are not the pattern pieces I used to construct the actual shirt.  I was so engrossed in the process the first time around, I neglected to take any pictures!  Oops.  I'll explain the differences between the two versions as I go along.

One caveat:  I am by no means an expert.  I did what I thought made sense.  I tried searching the interwebs for guidance, but I am terrible at doing that.

FBA then conversion to princess seams
I couldn't find any information on which to do first, so I tried it both ways.

1.  I started with a traced version of the pattern.  I only had one copy and wanted to preserve the original in case I messed up.  Before you start to do anything, copy the grainline somewhere in the area that will eventually become the side front.  I always forget to do this and have to backtrack to figure out where the grain is.

2.  The horizontal bust dart looked a little high, so I redrew it to point closer to the vertical waist dart.

3.  Next I used the slash-n-spread method to make a 2" FBA.  In the first version, I only made a 1.25" FBA because I thought I would have enough room based on the finished garment measurements.  I ended up having to add 1" seam allowances at the bust area

Notice to keep an even width down the front, a super large dart is needed.  My dart measured 4.5" (11.4 cm) at the widest point.

4.  To re-establish the vertical dart, I kept the right dart leg and copied the left leg from the original pattern.
I don't know if this is right or not, but I realize that redrawing the dart like this takes away some of the additional width that's added by the FBA.  The additional is taken away at and below bust level. I'd have to think about it more should I attempt to do this again.

5.  To find the shoulder princess line, I measured the width of the shoulder, minus seam allowances and divided the result in half.


6.  Next I drew a straight line from the middle mark to the top of the vertical dart.  Then I used a curved ruler to soften this line so that the seam curves gently over the upper chest.

7.  Before doing any cutting, make hash marks for notches above and below the bust curve.  Again, this is something I forget to do until after the fact.  I end up having to "walk the seam" to find decent match points.  Things are much easier if you identify these points now!

I cut along the curved line, stopping at the top of the vertical dart.  Then I cut the bottom leg of the horizontal dart also stopping at the top of the vertical dart.  Doing this turns the top of the vertical dart into a pivot point.

8.  Next, I closed and taped the horizontal dart.  This created a shoulder dart and the shoulder princess seamline.

 9.  To separate the panels, I continued cutting along the vertical dart.

Notice that the side front panel has an unsightly point at the bust.  I used a curved ruler to round the area.

Here are the side front and front pattern pieces:

I marked "Add SA" everywhere along these seams as a reminder to...um...add seam allowances. =)

In Threads #170, Connie Crawford suggests adding 1/2" of ease at bust level on the side front panel only.  I didn't do that on my first version, but did so on the second version.  I haven't sewn a muslin of the second attempt, so I don't know if this extra ease is needed. 

Below is a picture of the first and second versions.  Doing a 2" FBA as opposed to a 1.25" FBA appeared to not create that much more bust space.  I find that very odd.

(first attempt on top)

Notice how angled the armhole is on the second version.  Hmm.

Using the pattern pieces from the first attempt, 1" seam allowances at the bust, and 1/2" seam allowances everywhere else, here's how the blouse fits:

These are pictures of my for-real fabric.  I liked the muslin enough to proceed with cutting out my fashion fabric.  Not too bad, eh? I could probably use some more tweaking somewhere.

Princess seam conversion then FBA
Doing it this way was less successful, in my opinion.  The resulting armhole on the side front panel was so skewed it looked almost alien-like. 

The process is pretty much the same:
  • find the shoulder princess mark on the shoulder 
  • draw the princess seam line from this mark to the top of the vertical dart
  • cut along this line and along one of the horizontal dart legs
  • close the horizontal dart
  • separate the panels by cutting along the vertical dart

I made a 2" FBA again using the slash-n-spread method:

For comparison, the first attempt (FBA then conversion) is on top of the third attempt (conversion then FBA).  As you can see, I definitely have enough room at bust level, however look at the angle of the armhole - that just does not look right. Additionally, the front panel is much longer than on the first two attempts. 
I think doing the FBA first and then converting the result to princess seams is the way to go.  Even though I had to add an extra wide seam allowance, I was able to get the top to fit reasonably well.  As such, I am a bit more motivated to try darted fronts now knowing that I can make this conversion.  I'm not going to go searching for darted fronts because working with already-established shoulder princess seams is so much easier.  However, if I find a design that I like, I am not afraid to tackle it.
I hope this was helpful!  If you have any questions, feel free to ask in the comments.
Up next:  I need to finish the blouse!  My iron started smoking and going crazy yesterday, so sewing is stalled until I get another one and/or setup my gravity feed iron.  Did I mention I bought a gravity feed iron? =)


  1. Lynn is is a fabulous tutorial. You made it look easy. Well done!

    1. Thanks KMQ! I hope what I did is understandable. =)

  2. You amaze me! This is another tutorial that is getting stored for future use. VERY nice.

    I realized that I was "hating princess seamed tops" but the MAIN problem was that the bust point was too high and you taught me how to fix it! Yay! :)

    1. Thank you! I'm glad you got the fix for lowering the bust curve on princess seams. They really are flattering when that curve is in the right place. =)

  3. Thank you! Thank you! Thank you! The "FBA first or conversion first?" question is one of the reasons why I've only thought about doing this but have yet to try it.

    1. You're very welcome! Give it a try Michelle. I think you'll be pleased.

  4. I hate those pointy BHD's too! Being a G/H cup, darts are a necessary evil. Princess seams used to remind me of old lady dresses. Not until I started taking sewing seriously did I begin to realize the beauty and fitting ease of princess seams. If I can find a way to avoid BHD's, I do so. Thanks for tutorial. I am in the process of completing my armhole and shoulder princess sloper to use for my patterns.

    1. I'm a G cup with a small band, so getting stuff to fit has always been a challenge. Princess seams are so kind to full busts. I would love to see your princess sloper and how you use it to adjust patterns.

  5. splitting the HUGE dart into two is another option that works well. make the second dart below the first and angled upward toward the apex. that eliminates one giant dart and allows you to change bra styles because the 'cup' fit is more forgiving.

    1. Ah yes, that is a way to handle big darts. I tried that and never seemed to get them pointed in the right direction. Plus sewing them was always a challenge.

  6. Great tutorial! You can always smooth the resulting wonky armhole after any kind of FBA ... just sayin' since it's not always an obvious thing.

    I don't think it matters which is done first. If you had done the same 2" on both versions, I think you would've ended up with nearly the same pattern pieces. Hopefully I'm reading correctly that the FBA-first version was 1.5" and the princess-first was 2" ?? And ... you can also rotate part of the BHD to the waist dart instead of all toward the shoulder... depending on if you need to remove more of the resulting extra width from the waist. With my waist (or what's left of it), I don't. Hahahaha!

    Your resulting blouse fits so nicely! Well done. :-)

    1. Thank you! For the first version, I did a 1.25" FBA. For the second and third versions, the FBA measured 2". I forgot that we could rotate part of the dart to the waist. I have to try that.

  7. Thanks for this post Lynn. Very helpful and informative. Great info. And I love the fit you have achieved.

  8. The princess seam was invented to do just what it is supposed to do - fit any curve on a woman's body. If you have a fuller figure, it's the only shaping to use - darts just don't contour enough. And you can take in the back - as you have already said in another post, full fronted girls often have smaller back, so as you are discovering, this is the only way to really fit a garment for your sort of shape. By the way, the blouse looks fantastic - no pulling over the chest, and the back looks good too :)

    1. I totally agree. I've had minimal success with bust darts because, as you said, they don't contour enough. Since I have a full bust, princess seams help get the right curves/fit.

      Thanks SL!

  9. I get anxious just reading your fba....that's why I use pattern software. Thanks for making me appreciate it all over again.

    1. LOL. You're welcome. I have yet to try pattern software. I'm mixed about it because I've read reviews where people create a draft using software and still up making FBAs. In my perfect world, FBAs don't exist. =)

  10. Great tutorial... Thanks for sharing.

  11. Great result, looking forward to the finished blouse.

  12. I like how you think. The blouse fit looks great and following what makes sense to you is the way to go. Just look at the fit on that blouse.
    PS. My iron got replaced this week too.

    1. Thank you Maria! Making stuff up as I go along works for me. =)

      My iron cooking itself was the best. It forced me to put my gravity feed iron together. Holy hot steam!

  13. What a great tutorial.. I am a G cup and princess seams do fit better. I was a little scared about converting large darts but you made it so easy..


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