New user - using seamly and making precise curves and underwire questions


I recently found this software about a week or so ago and have been spending a lot of time learning all about it. I’ve never used patternmaking software, and have only been making my own patterns for the last 3 months. My latest test pattern from this actually worked out reasonably well!

I had a few questions while I continue learning. I would share my files but trust me they are nightmare material for the devs and seasoned patternmakers :joy: I am working on making a cleaner better second pattern draft.

Right now my projects are for bra making, following a few different books as needed.

  1. I need to make sure my curves are precise. Inner bust arc, outer bust arc, horizontal bust, wire length, apex… I am really struggling with easily making curves that are the right measurement.

It takes a lot of tweaking and adjustment to get close enough. I have seen other tutorials but most assume you are making an underarm curve with 7 points which is far more than I have to do.

For example the bottom inner cup top edge seam needs to be (InnerBustArc-1/8"). I need 90° joins at corners that join other pieces (Eg, at Apex point of both bottom inner cup seam which will match the Apex point of bottom outer cup)…

  1. To add to this, how the heck should I be drafting the underwire + splay, to get a reasonable approximation of the shape with the precise measurements. I feel like I’m trying to hack the matrix with all my reference lines and scooting curves all over to get the end result ok. The underwire I have has no pdf references available although I could scan and pdf the scan… But can I even use this in seamly?

My example is: 4.75" width 8.25" long 3" deep

  1. The Shin method of drafting has you draft the underwire, then measure up something like 1/8" on the inside of the underwire, and then continue drafting using this new line. This is to accommodate the seam allowances and channeling seam. Is there an efficient way to make this happen with the software? It’s trivial with paper and pencil but not so much on a computer.

  2. if I make a pattern piece, I can’t refer to a newer pattern pieces measurements. For example, I made bottom cups and started the top cup, then moved to making the band+cradle. The top cup needs measurements from the cradle, but I cannot refer to that newer pattern piece when I go back to the older upper cup. I know this now… but it would be good to be able to somehow have an “update” button to make the latest measurements available for older pattern pieces.

  3. during the details and layouts phase, what is the recommended method for seam allowance, so I get the edges of pieces squared better? My first try resulted in the bottom inner and outer cup having rounded edges which gave me difficulty when sewing. I am used to making the edges straight so I can more easily see and match the 1/4" edge.

Thank you!


Hi and welcom @Ailurus

I’ll try to reply to you:


This is a chat that helped me to make very acceptable curves: Another "very mathematical" way of making curves!

And this one, too: Curves with Formulas

I haven’t tried the methods on the small bra pieces, so I wish you luck :slight_smile:


Haha, yes, it gets like that. I suggest making these lines in yellow and dotted so they’re not in your face all the time. I did the free online tutorial which I posted the results of and the link in this chat: Bra pattern? - it’s about half way down the page but it may help you to read most of the chat :slight_smile:

And you can place them in a group once you’re done with them and close the ‘Eye’ on the bottom right of the screen to hide them from view.

And here is @AVI’s tutorial using the Kristina Shin method: Kristina Shin Basic underwire bra tutorial with all the discussions.


You can try using the Move tool which will create a copy of the selected and move it to a new location. image


Hmmm, yes… You’ll have to delete what you did on the top cup and start over after you’ve done the cradle.

There is a method of selecting a point in ‘History’ and inserting a few lines and points before the parts that need reference to them, but it’s very finicky and could end in an error, so I do suggest you save often and even, perhaps save the file to a new name before even attempting this. Here’s a link to where I explained it previously: Hacking Points in Pattern Files


My preferred angle setting is ‘By Length’, which I used in my trial in the previous reference. However, you should play with the settings to get it the way you want, as explained in this chat: Unexpected behavior when altering seam allowance between two points.

I hope these help you. Please don’t hesitate to ask if something isn’t as clear as I expect it be. Above all, have fun. I’m also loving this program :sunny:


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.

  1. 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. :slight_smile:

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.

  1. 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.

  1. I’ll try this! Thank you!

  2. 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

  3. Good to know! I will try and see what works best.

Thanks again for your help!


I seriously suggest at least reading what is posted on this site:

Mainly because they explain exactly how to re-create the shape of the underwire and all the different ones that you get. It may explain a lot to you with regards to some of your questions. You are also very welcome to download the pattern and the measurement files that I posted on the forum that I created from this site. They may help you to see what I did with regard to the measurements and the pattern. I haven’t actually made up the pattern, since I did it out of curiosity more than anything else, since, like you, I’m also only learning how to create my own patterns (I only started after I found this program :slight_smile:).

If you mean this line: image

How I read it is that to create point A9, use the tool Point at Distance and Angle from point A5, the distance (length) is 1cm and the angle is AngleLine_A3_A1+90 degrees. This is the amount that the curve needs to curve outwards to create the cup shape.

Yes, basically, you create lines from one point to the next that are outwards and downwards from the points used in to create the curve. Then you use those lines *.55 as the formula for the curve handle lengths and the angle of the line + or - 90 degrees for the direction of the handles. It really does work beautifully for the armhole shapes and the sleeves but I haven’t tried it on something as small as a bra cup. I used the same trial & error method that I think you have used.

Haha, that’s wishful thinking. No, I’m sorry, not yet. Perhaps sometime in the future.

Have a browse through the link I posted above.


Thank you for all your help Grace! I will be spending some time reading through all the information and taking notes. This software is really a great resource to have. It cuts down on so much time and trouble I have in drafting by hand. Knowing that if my measurements change at some point, the pattern can be recreated quickly with the new measurements, that’s just wonderful!

I have that same link for the Pattern School bookmarked! What a gem - I found it recently, maybe through here at some point. (Sidenote - I wonder what other useful craft knowledge has been lost through time on the internet…)

I have been playing around more recently and I found some reasonably good methods since then that may work for creating the underwire - I still have to spend more time playing around and see how it goes.

Finally I realized the only thing I’m really missing is the ability to “walk” seam corners together on my pieces. For example, matching the top seam of the inner and outer bottom cups in order to make a smooth join line. This isn’t a dealbreaker at all, I just know that after printing my pieces I need to take a minute to do this with the pattern pieces before using them.


Yes, that site was taken down for quite a while and then they put it back :slight_smile: I’m also ever so pleased.

@slspencer told me long ago somewhere on the forum that the handles need to be at 90 degrees to something that you wish to line up, to create your straight sewing line. To do this, you can play around with the one side of a line being at -90 degrees and the other side of the line being +90 degrees. You can also have the one side being 180 degrees (or more, or less) of the angle of the handle of the previous one.

It’s an amazing program. I started off by creating multi-measurements that fit a range of sizes, create my pattern, checking that the curves work nicely by changing the height and bust size of the person, and once I’m happy, I load the individual measurements.

Doing this, I’ve been able to make basic patterns (easy-fitting) for a few people using the same pattern, only changing the measurement files. But, hey, that’s my learning curve and I’m absolutely loving it. :slight_smile:

And there are some very nice tutorials in the wiki, including reference manuals in pdf. I don’t know if you’ve found them yet: User Manual - Seamly2D - The link is actually at the very top of the page “User Manual”.


Hi @Ailurus! Thanks for the feedback about “walking” seams. It’s possible to do this manually, but it would be nice to have a utility which matches seams together, and flags them if they don’t match.