# Mirrored Mesh won't weld or combine verts at seam

**URL:** <https://discourse.mcneel.com/t/mirrored-mesh-wont-weld-or-combine-verts-at-seam/59631>\
**Category:** Rhino for Windows\
**Created:** [April 4, 2018, 6:55am UTC](https://discourse.mcneel.com/t/mirrored-mesh-wont-weld-or-combine-verts-at-seam/59631 "2018-04-04T06:55:45Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Michael\_Pryor](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/michael_pryor/32/489117_2.png) [@Michael\_Pryor](https://discourse.mcneel.com/u/Michael_Pryor)\
**Post date:** [April 4, 2018, 6:55am UTC](https://discourse.mcneel.com/t/mirrored-mesh-wont-weld-or-combine-verts-at-seam/59631/1 "2018-04-04T06:55:45Z")

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I haven’t run into this problem before so I would like to know if anyone knows a solution to this or at least why it is not working. I have a mesh which I have split and mirrored. I am trying to join the two mesh halves together so that there is not duplicate verts at the seam, reading as an open naked edge. I have tried Welding and C# mesh.Vertices.CombineIdentical(); which are what I usually use but for some reason it just doesn’t want to become one. Mesh in question attached. [1.3dm](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/9/6/966d7a62d25878de6176fee2688e73ffc383a3ed.3dm) (129.5 KB)

 ![Untitled-1](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/1/1/110b69ba421f619566737db9264c7ea4fc7afadb.jpg)

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**Author:** ![Michael\_Pryor](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/michael_pryor/32/489117_2.png) [@Michael\_Pryor](https://discourse.mcneel.com/u/Michael_Pryor)\
**Post date:** [April 4, 2018, 7:02am UTC](https://discourse.mcneel.com/t/mirrored-mesh-wont-weld-or-combine-verts-at-seam/59631/2 "2018-04-04T07:02:46Z")

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Edit: Just found this and tried and it worked. Not really sure why though I cannot seem to find any non coincident points there at the seam.

> [@My Meshes won't weld](https://discourse.mcneel.com/t/my-meshes-wont-weld/22115/2):
>
> Hi Arthur, Weld only works if the vertices are coincident within tolerance. If you zoom in closer you see that this is not the case. To Weld this mesh, check first that the normals are pointing in the correct directions, then join it. Unselect the mesh and run: \_AlignMeshVertices \_SelectNakedEdges \_All \_Pause 0.1 \_Enter The \_Pause in the macro is that you can select the mesh. This works only post pick, otherwise the \_SelectNakedEdges option is not available. After this, \_Weld 180 should work …

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**Author:** ![clement](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/clement/32/759176_2.png) [@clement](https://discourse.mcneel.com/u/clement)\
**Post date:** [April 4, 2018, 6:31pm UTC](https://discourse.mcneel.com/t/mirrored-mesh-wont-weld-or-combine-verts-at-seam/59631/3 "2018-04-04T18:31:35Z")

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Hi @Michael_Pryor,

it is strange i can weld manually using `_Weld 180` in RH5 and RH6. Doing it with python it only works using `mesh.CombineIdentical` if i set `ignoreNormals = True`.

```python
import Rhino
import scriptcontext
import rhinoscriptsyntax as rs

def DoSomething():
    
    mesh_id = rs.GetObject("Mesh", 32, True, False)
    if not mesh_id: return
    
    mesh_obj = rs.coercerhinoobject(mesh_id, True, True)
    mesh_obj.Geometry.Vertices.CombineIdentical(True, True)
    mesh_obj.CommitChanges()
    
    scriptcontext.doc.Views.Redraw()
    
DoSomething()

```

\_  
c.

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<div class="post-metadata">

**Author:** ![Michael\_Pryor](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/michael_pryor/32/489117_2.png) [@Michael\_Pryor](https://discourse.mcneel.com/u/Michael_Pryor)\
**Post date:** [April 4, 2018, 6:39pm UTC](https://discourse.mcneel.com/t/mirrored-mesh-wont-weld-or-combine-verts-at-seam/59631/4 "2018-04-04T18:39:05Z")

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I believe it is some tolerance thing going on. If I move it away from the origin I was able to get it with Weld 180. When not, I had to do \_AlignMeshVertices then Weld 180. In the end I am using a c# method for welding within a distance tolerance as I needed it for a script anyway. Seems to catch it every time now.