How do I work with/ replicate splines on multiple pattern pieces

[Tracsri]

I’m new to the forum and fairly new to using Seamly although learning fast.

I’ve drafted my first pair of pants and it’s going well. I’ve uploaded the file here.

What I really want to know is what is best practice for reusing the curves on a spline across multiple pattern pieces or slices?

Here’s the scenario:

I have a pants side seam.

I have a main spline that connects the waist to the pant base starting at WF2a and ending at LnF5 (the base of the pant). I’m using this as a backbone.

I have a variable that drops the waistline from the true waist by a custom amount, say 2cm. This is WHFa- constructed as a point on SplPath_WF2a_LnF5 (not an actual control point, just a point on).

I have a pocket. Its length runs from WHF2a to PF3- a point also constructed as a point on SplPath_WF2a_LnF5 (name not shown on diagram).

All great until I’m trying to piece. To get a separate piece for each of the pant front and pocket with the notches correct, I need to draw two new splines- one for the pant front with the dropped waist and one for the pocket. But then trying to keep all three in sync and on top of each other seems to be impossible and very fiddly.

I feel like this must be a common problem as it’s quite normal to want to reuse curves by cutting them up. Do you have any tips or suggestions for managing this?

MarilynSDForStetchWovenPantsSD003a.sm2d (98.6 KB)

TracySept2025.smis (2.5 KB)

[Douglas]

@Tracsri

What I really want to know is what is best practice for reusing the curves on a spline across multiple pattern pieces or slices?

Just reuse them. You can make as any many pattern pieces from the points and curves in a draft block as you want. There is no need to draw curves over one another.

@Tracsri

All great until I’m trying to piece. To get a separate piece for each of the pant front and pocket with the notches correct, I need to draw two new splines- one for the pant front with the dropped waist and one for the pocket. But then trying to keep all three in sync and on top of each other seems to be impossible and very fiddly.

Ok.. one issue I’m finding is… when you create a new piece and you want to include notch points on a curve you have to click the curve, the notch point, and the curve again. The app knows how to break the curve / spline into segments based on any points on curve you’ve included. For example:

This is no good:

I redid the pocket piece and you should see how it goes from

WHF2a
 SplPath_WHF2A_PF3
PF1
 SplPath_WHF2A_PF3
PF2
 SplPath_WHF2A_PF3
PF3

And if you look at the front piece… the main path is also no good… you’re just drawing straight lines from WHF2a, to PF1, to PF2 to PF3… there’s no curve in between.

You can insert nodes to an existing pattern piece usimg rhe Insert node tool:

Which I did here… I actually inserted one curve, and then just duplicated it twice using the context menu:

Now the front side seam & notches will match the pocket.

I would also fix some of the control points as some curves get a bit wonky in spots:

I removed the formula at CLF4 as it puts a kink in the seam. Again there’s no need for the other spline. Note: With splines… the control points at nodes are fixed at 180 degs apart. If you add a formula to one of the control points you’ve fixed the other point.. thus the kink above.

[Tracsri]

That’s brilliant, thank you so much. Makes sense now.