Built in seam allowance

I’m on to the next issue to resolve… implementing a built in seam allowance option. Yes, currently there’s a “built in” checkbox, but it really doesn’t do anything more than hiding the seam allowance (cut line) and disabling all the other SA options.

While on the surface it seams (pun intended) that all that’s needed is to be able to use a negative seam allowance width - if it were only that easy. What really needs to happen is if the seam allowance is built in, a new main path needs to be created on the inside of the main path at the given node SA widths - WITHOUT the angle types at the corners. Then with the new main (which will now be the seam line) path it’s run through the routines as usual to create a new cutline with the appropriate corner types. Again easier said than done. I have decoded the corner routines and have been able to find the corner points inside the main path. Now I have to figure out creating the curves inside the main path, and connecting it all up for a new main path. :thinking:

Another issue I have to resolve is being able to add “makeup” to the seam allowance between designated nodes. For example… it’s common in many systems that the draft includes the seam allowance - my experience has been the included SA is 1/4", but requires additional width added at certain places. In the pic below an additional 1/4" is added as makeup from A to 17 to 20. In other words we need to be able to set the SA to 1/4" and add an additional 1/4" makeup from A to 20 so that when the pattern is printed the seam line is still printed at 1/4". Make sense? This was a issue I ran into making the vest patterns for Annie… I worked around it by adding a default 1/4" SA and 1/2 Sa from A to 20… then disregarded the printed seamline knowing there was a 1/2" SA all around.


Also I played around with the dialog, and what we really need is 3 options for the SA… None, Built In (I may change this to “Included”, and Added. And to be less confusing, make the Hide Seam Line… Show Seam Line where choosing none disables Show Seam Line and checks Show Cut Line as there is no seam allowance - so it’s just a cut line which has to be shown. With the other two SA options at least one of the show options has to be checked - otherwise nothing will show.


That’s all for now. :slight_smile:


Hmmm… Sounds very nice. I think that the original ‘Built-in’ was just to say that you don’t want SA because it’s already built into the pattern but that you still want the notches to show on the cut edge. Previously, we didn’t have the option to show the notches on the cut and/or stitch lines.

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Bei Teilungsnähten, beispielsweise am Armloch machen die Nahtzugaben einen Unterschied, wenn ich die Naht auseinander, bzw. in eine Richtung lege. Diese Möglichkeiten sollten manuell zu ändern sein.

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Correct. The obvious problem with that is there is no way to see the seam line or what the seam allowance is supposed to be for end users of a pattern. Plus like I mentioned there is no way to account for any additional makeup allowances other than adding additional drafting to account for it.


Does ‘Built In’ and ‘Added’ have more meaning than ‘Internal’ and ‘External’?
Does ‘Built In’ translate well?
Does the opposite nature of ‘Built In’ and ‘Added’ come across in other languages?
Also trying to improve the vocabulary of sewing in general to phrases that are less ambiguous.


I don’t like “built in” either… I prefer “Included” and “Added”. Most books I used will usually say to the effect “seam allowance included”… but I’m open to what ever the consensus is


Just for reference…

From Sew Magazine:

“Seam allowances are included in the patterns that you will be using to create your garment or piece of fabric. This means that you do not have to add them yourself, and they will be automatically added when you trace the pattern pieces on a separate paper.”

So… seam allowances are either included or added… not internaled or externaled.


Since we’re refining the vocabulary to be more specific, could we use ‘Internal’ and ‘External’ as radio buttons for seam allowances?

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We could, but who uses those terms in regards to seam allowances?

Tell any sewer that the seam allowance is “included” they know what you mean… say it’s internal and they’ll go huh?

I get the concept of internal / external in regards to the main path, but down the road even that could be confusing when I figure out how to add SA allowance to internals. For ex: A circular cut out… would the SA be internal or external?

Take a poll… see what other’s think.


Or how about Integrated Vs. Attach?

We all know, & agree, that Seamly is intended to revolutionize the fashion industry. Which doesn’t actually mean anything. That is to say that I can see two incompatible meanings without trying.

  1. does it mean that Seamly is the premier FOSS option allowing disadvantaged schmucks to enter the fashion & costuming industry, or
  2. does it mean that Seamly is trying to completely re-write the industry by being a superior program which only industry outsiders can comprehend?

It is my impression that @Douglas believes the first option to be the true meaning, while RT believed the second option to be the true interpretation.

I say, let’s not go using industry incompatible phrasing just to be different. However, if upon consideration a different phraseology is clearly superior, by all means let’s adopt it, but never forget that Industry Standard does bear some weight in deciding.

I find Douglas’ defense of included over internal to be convincing. I also feel that my counter-suggestion of integrated is clearer than internal. I do also like it better than included, but acknowledge my completely non-standard linguistic heritage.

The main value I see in external is that it’s an antonym to internal. My recommendation of attach conveys the idea that an additional element is being tacked on, but I feel that add, an otherwise close second, has it beat on virtue of being an industry standard term.

Anyway, that’s my semi-serious, slightly silly take on the question.



My guess is that if I were new to sewing and pattern making, my first step won’t be to go straight to Seamly… I would start by reading some articles and ask other seamstress and designers for the basics. And by doing so, I would come to Seamly with some hints of the usual vocabulary.

To me, “Included” and “Not/Non Included”, as “Built In” and “Added” are interchangeable, as both would translate to “Inclus” et “Non Inclus” in french. That said, if I was to encounter the latter terms for the first time, not being a native english speaker, I would have to check what “Built In” really means,

“Internal” and “External” sound a bit confusing.The allowance would be internal or external to an actual pattern piece, but in the first case, it would be the sewing line, and in the latter the cutting line ?

I really don’t know about “Integrated” and “Attached”. What would be their counterparts ?

So. My preference to “Included” and “Not Included”.


Agreed. While as a draftsman I get the concept, like I said I don’t think that translates to your average sewer. Having employed sewers for nearly 40 years, most of them would go huh? If I said the SA is internal / external.

Except that “not included” does not convey that you are adding seam allowance to the main path of a given pattern piece.


My ha’penny’s worth… I think we have to leave a bit of space for SA on internal paths, which has been discussed a number of times and could possibly be in the pipeline for the future. So perhaps we should first decide how these will be named, to reserve them, and take whatever’s left for the main lines?

I’ve been waiting for someone else to mention this… and you’re making my point. Once we are able to have SA’s on internal paths is the SA internal / external… or does not included / added make more sense?


:thinking: Good point.

Well then, to me, Added/Not Included seam to be the less ambiguous terms.

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Another, slightly wordy, option would be “Drafted in” & “Not drafted in”

It seems that “Included” & “Add” are the best couple, possibly with “Seam allowance included in the basic draft.” & “Seam allowance needs added to the basic draft.” as tooltips.


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Yes… expanding the tooltips text to further explain is always helpful.

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I think we’ve all been thinking in terms of what to call the included and the added SA without regard to the None option.

My take is whether the piece HAS seam allowance… not WHERE the seam allowance is. To me it either HAS None, it’s HAS allowance Included, or it HAS it Added.

So question is… where does None semantically fit in with Internal and External?

If the UI was asking where to place the seam line - then it’s a question of WHERE, but that’s not what we’re looking at. You can only determine WHERE it is after you determine if it HAS seam allowance.


If adding a negative seam allowance is permitted, (which many people have tried before to much aggravation,) then I think that “Has seam allowance”, ditch “Built in” —notches can be assigned a location in the notches tab (if no seam allowance, they default to showing at their point, regardless of checkbox.)

I believe somewhere in this thread was mentioned the possibility of both extending a cut line out from the draft line & a seam line in from the draft line, which would necessitate something a little more complex. Possibly reassigning half of the dialog width to adjusting the seamline? I’m seeing room for it.

Anyway, I started replying before realizing that I hadn’t updated my installation for a month, so hopefully I got the outdated stuff scrubbed.


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Yrs, I like this idea to control the SA position with the +, 0 or -, rather than having little check boxes with names that could be misinterpretted. I’d even ditch the ‘has seam allowance’ unless it’s something that is needed for the labels.