Deriving Patterns from First Principles

[DengLinPiano]

Are there any resources available on how to derive the pattern of a piece of clothing from its original concept? How do I learn the rationale behind each step of a draft? Right now, it feels like I'm just mindlessly following instructions. Something that provides a commentary for each step of a draft for a suit jacket would be nice.

Thanks,

From a complete beginner. 

[Schneiderfrei]

How far back do you want to go DengLinPiano?

Which drafts have you attempted?

It is true that the draft is simply an algorithm, but finding background on particular draft systems can be difficut.

There is a historical perspective to consider overall.

you might try this, it has a reasonable explanation of the draft.  It was published in the early 70's

https://movsd.com/BespokeCutter/index.php?topic=508

There are some very alterative approaches in the wider literature as well.

G

[Gerry]

When I was first learning to cut, I felt the same frustration. The most intuitive book on the subject that I know of is Don McCunn's How to Make Sewing Patterns. It's not comprehensive, and doesn't include all the tricks that tailors use, but it's a good foundation; and (for me) it made those more obscure books on cutting easier to comprehend.

At some point, though, those old, cryptic books do need to be studied. They contain a wealth of information that is mostly missing from modern publications.

[LindyBalboa]

I am no pro and I don't have a specific resource in mind, but I can tell you how I am currently thinking of trouser patternmaking. There are a few critical measurements, and the rest is just growing out from those points.

The most important measures in a trouser draft, as far as I view them, are:

• The hip circumference
• The hip height from floor
• the distance of the front grainline to CF at hip height
• the distance of the rear grainline to CB at hip height
• crotch depth (front to back)
• crotch height from floor

The hip height/circumference is absolutely the most critical to the fabric just sitting on the body somehow. There is a reason the "scale" of drafting systems is based on the hip. I view the points CF-at-hip-height and CB-at-hip-height as the origins of my draft, even if they aren't the first thing I draw.

The grainline to CF/CB at hip height is an idea that I discovered from this post: https://handmadephd.com/2021/03/13/crease-line-placement-at-the-hips/. I find that most drafts place the grainline 1cm too far in or out for me from what I have measured on myself (with the help of my most patient girlfriend). It has a direct influence on how deep (laterally) the front and back crotch curves are, and how much the side seam protrudes and is rounded at hip level. Once this distance is established, the remainder of the hip measure extends to the side seam.

The crotch depth is another measure that is critical to the pants fitting on the person. This defines the sum  length of the "horns" between CF and CB. The distribution of this measure front to back seems to vary quite a bit and is usually calculated from the scale (hip dependent). Rory Duffy's draft for flat-fronts is 1:1.75 (front:back) and the Müller and Son HAKA flat-front draft is 1:2.6.

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I view the seat angle and the waist circumference/height as the next most important.

The seat angle determines how much fabric is available for the bum to fit into at CB. I don't know of a dead-on way to measure this-- you just have to pick something in a "standard range" and fit it. Rory Duffy adjusts the angle based on how much "drop" there is from the hip measure to the waist measure. As the waist gets smaller than the hip, the angle becomes less steep aka further away from vertical.

The length of CB isn't super critical. You can measure it directly from hip to waist, or use one of the drafting systems' methods. Again, it just needs to be close to correct and fitted on the wearer (thank goodness for inlays).

The top of the side seam (waist height) defines the guideline upon which the front waistband falls--- from side seam to center. The guideline of the back waistband is defined by the top of the side seam and CB.

For a normal figure, the job is to obtain the waist measure by reducing the hip measure either through darts, pleats, easing, and/or curved seams, such that the waist is close to inline with the hip when cut out. How this is achieved is largely up to the cutter and the style desired. One simply starts from CF or CB and adds the features along the guideline until the desired waist measure is obtained. It is usually recommended to plan your darts, pleats, and easing so that the top of the side seam (as marked and cut) falls close to vertically above the hip or just inside of it.

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The knee and hem width are the least critical, are largely a matter of style, and are symmetric about the grainlines for normal figures. Knock knee and bowlegged are a whole other can of worms that I have no experience with.


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I know you asked about jackets, but hopefully you find this "first principles" focused description useful. I'm sure some of what I wrote is probably confusing because I've never written out these ideas before, so feel free to ask for clarification.

[Greger]

Here is an old methods, of which there are many that have passed on.

Single Breasted -  https://www.youtube.com/watch?v=B7MzAziwgeU

Double Breasted -  https://www.youtube.com/watch?v=854sjZvK51I