Hello everybody !
I'm a french sewer and I want to use SE 2D to draft patterns.
The aim is to obtain a pattern which varies automatically according to different standard sizes (36, 38, and so on).
So I created an excel sheet with variables including measurements, linked to the SE file.
But I have now an issue and I find no answer to solve it.
I draft a bodice pattern, which implies to draft a dart. It's a little triangular opening which is created between the shoulder and the chest. To place definititely this triangle, I must rotate a previously drafted triangle center of rotation = chest;
origin = line from shoulder to chest;
destination point = a certain distance which varies according to the chest measurement. As by hand we use a layer to do this, I created a circle whose radius varies according to a formula based on the chest measurement, and the destination point is tangent to the circle.
The problem is, when I use this method, it works very well for the size I indifferently work at (in the example of the file : 38), but when I change the size afterwards in the excel sheet, the dart is rotated but not well placed anymore. It is not fixed on its origin point on the chest and not fixed on the circle anymore.
Has anyone an idea to solve this issue ?
I think I have perhaps to constrain or connect my triangle to the center of rotation on the chest, but when trying, I don't know how to do and it doesn't work ...
Moreover, I just realized that after rotating, the lines don't keep their original lenghts. So the parametrical relation is not applied when rotating.
But I have maintained the relations all the time while drafting, I don't understand why it doesn't work.
I don't know anything about sewing, so I'm pretty sure that I'm not following everything you're saying, but I'm assuming you're talking about the triangle in the upper right corner and the smaller of the two circles located in the same general area. I notice that nearly all of your dimensions are pulled from your excel sheet, and that most of the exceptions to that rule are located in that upper right corner. In that corner you have three different locked dimensions, and no tangent relationships anywhere that I can see.
Locking those dimensions mean that they won't change even as the rest of the dimensions do, and that might be part of your problem. If they need to adapt to values that are functions of other dimensions you already know, you can either put a relationship into the dimension itself or add more items to your spreadsheet, put the functions in there, and then make the SE draft dimension read from your spreadsheet. If they need to adapt, but you don't know what their values are going to be, you'll have to unlock them for them to be able to change as other dimensions do...but if they're unlocked, you'll want to provide additional constraints via relationships to make sure that those changes are the ones that you want. And that brings me to the final comment I have...
If tangency is something you require, you'll have to use the tangent relationship to force that tangency to remain as dimensions change. Right now, nothing in that portion of your drawing has any reason to remain tangent with any other part of your drawing, so I'm not surprised that you lost tangency the first time you made a change. You may need to change some of your connect relationships to "point-on" relationships (again, I don't know enough about what you're trying to do to be sure), but you'll definitely need to add tangency relationships to whatever you have that needs to be tangent.
Thanks a lot for your reply !
In fact, you have well assumed what I try to draft, and the problem I have.
It's wonderful that the issue has a solution, and the only problem is my unappropriate knowledge of CAD softwares.
I'm going to see it all over again and try to understand how the tangency relationships work, it's not really intuitive for me.
I'll post the result.
Right now, you've got things drawn up such that your line is touching the circle, but that's the only thing it knows it has to do. As a result, when the circle moves, the line will shift to make sure that it's still touching, but there's no reason for it to shift such that it is 1) touching AND 2) tangent. Adding a tangent relationship will tell it that it must also remain tangent to that circle. Just remember that SE pays attention to EVERY relationship and dimension, so if you accidentally overconstrain your sketch it still won't work the way that you want it to. Finding how a sketch is actually overconstrained can be challenging...I've spent a lot of time on a few occasions trying to figure out why I'm not allowed to place a relationship I know I want, and sometimes the reason is pretty convoluted.
Yes, I've read again the manual according to your indications, and I begin to understand what you mean.
In fact, the software is so powerful and full of functions that it's sometimes difficult to even imagine all the possibilities.
But right now I think I'm going to find the solution and I'll post.
Thank you !