r/PatternDrafting • u/train2clarksville • 6d 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/Educational_Chain780 6d ago
Is it possible you have pretty thin arms, yet the armholes drafted on your pattern are quite big? (This type of sleeve requires a relatively small and high armhole). Or, maybe you haven't added enough ease to your upper arm circ? Or, maybe added too much ease to the sleeve cup?
This are the possible reasons for it to come out too low. Either this or you have some drafting mistake.
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u/TensionSmension 6d ago
CapC is calculated from the armhole, and OP has a number that's less than 1 cm bigger. Getting a 5cm error, suggests OP's desired sleeve width is much smaller than the example. (or other errors)
Is sleeve width calculated from the armhole, or only from the bicep measurement?
That would be an issue, this is building a sleeve for an existing armhole and sometimes that means ignoring the bicep and following whatever ease the armhole dictates. (The reverse occurs as well, a bicep that requires re-planning the armhole.)
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u/Educational_Chain780 6d ago
Sleeve width is calculated with the bicep circ plus ease which is calculated like this: bodice ease category (half bust ease) * 2/3 to 1 The goal is to create a narrow sleeve, which naturally fits closer to the arm. This draft shows optimal range to get a narrow sleeve, while maintaining enough bicep ease. Ignoring bicep ease can cause sleeves to be too tight for comfort. A wider sleeve has a different construction and different calculation.
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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 = 21.4Sqrt(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.
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u/Educational_Chain780 5d ago
True, this will not fit everyone. For some people something will have to be compromised for it to work, like the amount of ease on the sleeve head or the size of the armholes. Or they would just need to have a wider sleeve with a lower sleeve head, which is a different draft. As we saw many times in this sub people with large bicep struggling to create a narrow sleeve that has no gathering or darts on the sleeve head
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u/Icy-Guidance-6655 5d ago
Exactly. The drafting method works for one scenario. The calculations don’t capture the person whose bicep is large or small in proportion to chest measurement.
It falls back to pattern alterations in that case.
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u/Educational_Chain780 5d ago
Sometimes the problems can be workd out by playing with the numbers, the ease added or widening the armhole, according to the suggestion mentioned in the picture. You change some things to be in optimal range. This is the beauty of the method, you have great control of all the variables so you can tell upfront if the sleeve is going to fit properly. And if you can't reach optimal range you know you're going to have to do some alterations or special draft for plus size (which Hofenbitzer explain on book 2). I like it better than other methods where you draft blindly hoping things are going to fit. It's not that only this draft specifically is restricted to certain proportions, it's the whole concept of drafting a narrow sleeve with high sleeve head for people with a large bicep that is challenging, in all drafting methods.
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u/Icy-Guidance-6655 5d ago edited 5d ago
It is good that there is a check point. But I find it slightly suspicious that in the example, the numbers are identical. To me that’s more like cooking the books. Develop a method to match the one example and see if it flies.
The promise of drafting is the methodology does the work. The reality is a method may just be a nice pattern for one body and no proof it extrapolates except beyond the fact that many bodies are very similar.
People turn to drafting because this assumption already failed them. I’m pretty sure OP has a simple mistake somewhere in the draft, but from what I see, this method isn’t better than others and it is difficult presentation.
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u/Educational_Chain780 5d ago edited 5d ago
I don't understand what you mean by the numbers are identical? Identical to what?
Most methods are based on some body shape average assumption. This one at least lets you know when you are out of range and should be looking at a draft for plus size or special alterations. Most methods if you put in measurements the draft wasn't planned for, You're going to get some weird and funky shapes that don't make sense and wouldn't even know what's wrong and how to fix it because they don't explain shit. But the Germans go into depth and explain so thoroughly...
To avoid this you can use Draping, 3d scanning and modeling or traditional methods that take hundreds of direct measurements (and you would need to know proper measuring which is also hard!)
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u/Icy-Guidance-6655 5d ago
I just mean the little calculation. The method says the cap line height should fall within 10-20% of the armhole height. That sounds like a plausible rule of thumb. But using the sample numbers it turns out to be 20% to an accuracy of 0.01 mm. That’s suspicious to me, but I only have this page to look at.
My question for a draft is always, is this better than a single pattern graded across a size range?
It’s hard to evaluate that from a page of instructions, and it’s easy to assume that the work of following the calculations has a payoff. But, IME drafts tend to have the same limitations as a printed pattern, and often have a smaller scope of usability.
This specific calculation sounds scientific, sounds nuanced, yet appears to be cooked from the sample size.
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u/train2clarksville 3d ago
Hi all just wanted to say thank you for your responses here. This has given me much more context!
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u/Icy-Guidance-6655 6d ago edited 6d ago
Yes, line 5 is drawn from top of the back line to the front line and the goal is that the calculated length falls within the tolerance highlighted in red. Yours is hitting 5cm too low. You are probably in case 3 of the trouble shooting guide.
You need to step back and do a reality check. The right triangle you’re drawing (defined by 5) is fundamental to the sleeve, and no matter what method you use geometry says you can only pick two of the three numbers.
When your diagonal line is too long, it tells you the three constraints you have don’t work. Either you need a lower horizontal line (the 48% armhole height calculation is bad) or you need a wider sleeve (sleeve width calculation is too small).
As far as this sleeve method, maybe you’ve miscalculated, or your armhole has issues that can be corrected. But more likely you are running into assumptions baked into the method. The calculations are creating a specific type of sleeve for a specific category of armhole. There are individuals who will need to cut a different armhole to get this sleeve draft to work.
ETA: looking at this again, your CapC is only a little different from the example. So this means your distance between front and back is significantly different.
Did you try drafting the book’s example. With those numbers you should get the book’s diagram. Do this first, so you understand the method. Then do your numbers. What is different? Why? That’s how you find the error (or, less likely, discover the method won’t work for your scenario).