Thank you so much! I have been using the same links that you have referenced, so I’m glad I was able to find good references. The PDF made showing the Shin method is a great starting point. For example in the PDF A5>A9 - the amount used here may vary; I’m not certain how this is derived and the book doesn’t explain it. I’ve had good luck using 5% of InnerBustArc+OuterBustArc, as another book and website suggests 5% of horizontal measurement is a good rule-of-thumb for extending curves.
- Is this the math method you were suggesting ? Posted by KeithFromCanada on Sep '17 I see a huge amount of math and trigonometry… Unfortunately I never got past algebra in college 10 years ago so I have no idea if I would be able to digest this! I tried using the other post Curves with Formulas but it is very chaotic…
I wish there was something easier. It’s easy to get discouraged from a project if it takes a significant amount of time for a few reference lines out of many. I do have another patternmaking book and may try her method and see how easily things proceed compared to Shin method.
I was able to hack a solution and eventually saying “Close enough”. If the curve measurement ends up just a bit smaller (like 1/16"-1/8") in the curve than the reference measurement, it isn’t such a disaster when sewing and wearing the finished product. This assumes there’s as few “Close enough” situations as possible. There’s a little bit of forgiveness since the body isn’t rigid. 
My notes are at home but I will make a mental note to get some screenshot showing what I did and the formulas used. I believe I used reference lines such as [(InnerBustArc*.33)*.55], using a 1/3 point as control point and bezier curve math.
- Yes - Dotted lines EVERYWHERE! (Although I wonder now if you can select a few lines and change the style and color at once? One-by-one is tedious and sometimes I get carried away and forget to set this when making the lines). I love the Groupings. They are such a great feature to remove clutter.
The difficulty is in making the underwire curve to begin with and have it end up looking reasonably similar to the underwire used in the end product. I am actually using flexible underwires so I’m not in such a critical need of the pattern being close or not - but if it is a standard underwire, it has little-to-no flexibility with splay. If the pattern cradle doesn’t match well, the wire and bra will be wonky.
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I’ll try this! Thank you!
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That seems very risky… but it’s good to know if it’s a minor change that there may be an option. Thankfully I save often after some silly mistake crashed an early pattern attempt
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Good to know! I will try and see what works best.
Thanks again for your help!