# Grasshopper Loft Problem - multiple curves in list not lofting ("Loft could not be constructed")

**URL:** <https://discourse.mcneel.com/t/grasshopper-loft-problem-multiple-curves-in-list-not-lofting-loft-could-not-be-constructed/69031>\
**Category:** Grasshopper\
**Created:** [August 17, 2018, 4:46pm UTC](https://discourse.mcneel.com/t/grasshopper-loft-problem-multiple-curves-in-list-not-lofting-loft-could-not-be-constructed/69031 "2018-08-17T16:46:10Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![vlee85.uwo](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/vlee85.uwo/32/328021_2.png) [@vlee85.uwo](https://discourse.mcneel.com/u/vlee85.uwo)\
**Post date:** [August 17, 2018, 4:46pm UTC](https://discourse.mcneel.com/t/grasshopper-loft-problem-multiple-curves-in-list-not-lofting-loft-could-not-be-constructed/69031/1 "2018-08-17T16:46:11Z")

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In the attached grasshopper file, I am running into a problem with the loft feature. I have two sets of curves, “side curves” and “top curves”. I want to loft these curves together to create ribbing. The top curves can be lofted successfully, however the side curves encounter an unidentified error “Loft could not be constructed”. Both sets of curves were generated and sorted using the same components. I have checked the items below but I am not sure why one set of curves (top curves) works but side curves do not. Can anyone lend some insight?

Checked:

1. curves are in the correct order: for side curves they are sorted in the x direction.
2. all curves are closed
3. same type of curve (sometimes there are errors when you loft a line-like curve to something else, but this is not the case)

Best,

Victor

[Loft Problem 18082018.gh](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/3/9/392a1e669f374b7501f8ad0a168c1515d3cbc070.gh) (74.0 KB)

 ![image](https://global.discourse-cdn.com/mcneel/original/3X/e/b/ebcfafa1edf71b5b84c8afc90d032adfb010bcc5.png)  
 ![image](https://global.discourse-cdn.com/mcneel/original/3X/f/1/f1f6f6d94ae9b9031761efe8248083e10e8baefd.png)

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**Author:** ![akilli](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/akilli/32/514967_2.png) [@akilli](https://discourse.mcneel.com/u/akilli)\
**Post date:** [August 18, 2018, 12:01am UTC](https://discourse.mcneel.com/t/grasshopper-loft-problem-multiple-curves-in-list-not-lofting-loft-could-not-be-constructed/69031/2 "2018-08-18T00:01:57Z")

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I changed the curve seam alignment so it points to {0,9999,0} and you now get four lofted surfaces. Hope this helps.

 ![Canvas%20at%2004%3B32%3B06](https://global.discourse-cdn.com/mcneel/original/3X/f/f/ff9dc07bb44caf8ab73a77fba75e7ce63ed07ffd.png)

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**Author:** ![vlee85.uwo](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/vlee85.uwo/32/328021_2.png) [@vlee85.uwo](https://discourse.mcneel.com/u/vlee85.uwo)\
**Post date:** [August 18, 2018, 3:25pm UTC](https://discourse.mcneel.com/t/grasshopper-loft-problem-multiple-curves-in-list-not-lofting-loft-could-not-be-constructed/69031/3 "2018-08-18T15:25:47Z")

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Thanks, using point {0,0,0} works as well.

Victor

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<div class="post-metadata">

**Author:** ![akilli](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/akilli/32/514967_2.png) [@akilli](https://discourse.mcneel.com/u/akilli)\
**Post date:** [August 18, 2018, 9:41pm UTC](https://discourse.mcneel.com/t/grasshopper-loft-problem-multiple-curves-in-list-not-lofting-loft-could-not-be-constructed/69031/4 "2018-08-18T21:41:35Z")

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I like to travel.

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**Author:** ![doc](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/doc/32/306825_2.png) [@doc](https://discourse.mcneel.com/u/doc)\
**Post date:** [June 17, 2021, 12:19pm UTC](https://discourse.mcneel.com/t/grasshopper-loft-problem-multiple-curves-in-list-not-lofting-loft-could-not-be-constructed/69031/5 "2021-06-17T12:19:35Z")

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Hi there,

I’m reviving an old post that seems to be a similar problem that the one i’m experiencing.  
I’m trying to loft a series of curves to form a wing surface.

 ![2021-06-17_14h13_04](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/d/1/b/d1b07a118147f8342ca84f4d29ed10663b6b59a0.png)  
When I use the loft function, it doesn’t do anything. Is there a way to know why ?

I have tried creating the same line in Rhino then lofting them in Grasshopper, and it works.  
So it seems that the loft function doesn’t like the curves created in grasshopper.

Can you let me know what would be the possible causes ?