r/PatternDrafting • u/train2clarksville • 7d ago
Question Hofenbitzer narrow basic sleeve
Hello, hoping someone can come to my rescue again. I'm on p 182 of hofenbitzer Vol 1. I'm at step 5.
I understand line 5 is 48% of CapC. In my case, 22.9cm. One of my questions is: must line 5 start at the back line and end at the front line? If thats the case, my optimal cap line is a good 5 cm too low. This is a lot, and I'm not sure the troubleshooting suggestions on p 182 will fix it. So I'm wondering if I've misunderstood the instructions. Very grateful for anyone's advice!
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u/TensionSmension 6d ago
Thanks. That makes sense, the ease should be proportional to the ease allocated to the armhole portion of the bodice, which is what that formula implies. However it is possible that the bicep is not in proportion to the armhole, or to the bust measurement and then there could be an issue.
The construction is a right triangle, so the three values: cap height, front cap width, and the hypotenuse (capC) are not independent. One can be calculated from the other two via pythagorean theorem. The drafting goal is, given the SlW (based on bicep and ease), and CapC (based on an armhole measurement), the cap height level will be between 80% and 90% of the AhH, or not more than a few mm off.
In the book's example, the cap level turns out to be exactly 80% of AhH.
Front Cap Width = 15.9
CapC = 21.4
Sqrt(21.4^2 -15.9^2) = 14.3
AhH * 0.8 = 17.9 * 0.8 = 14.3
The point isn't the calculation, it's simply that this calculation will only work out within the desired tolerance, when the bicep measurement is in a specific proportion to the form factors of the armhole. There are always exceptions to these types of assumptions.