# Surface normals not extruding correctly

**URL:** <https://discourse.mcneel.com/t/surface-normals-not-extruding-correctly/92973>\
**Category:** Rhino for Windows\
**Tags:** cnc\
**Created:** [November 29, 2019, 6:28pm UTC](https://discourse.mcneel.com/t/surface-normals-not-extruding-correctly/92973 "2019-11-29T18:28:37Z")\
**Posts on this page:** 9\
**Page:** 1

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**Author:** ![Walid\_Butt](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/walid_butt/32/190130_2.png) [@Walid\_Butt](https://discourse.mcneel.com/u/Walid_Butt)\
**Post date:** [November 29, 2019, 6:28pm UTC](https://discourse.mcneel.com/t/surface-normals-not-extruding-correctly/92973/1 "2019-11-29T18:28:37Z")

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[1\_500 SCALE CNC\_(WALID).3dm](https://discourse.mcneel.com/uploads/short-url/644jBFGXhkVnYyGdwjh58CNSQee.3dm) (3.7 MB) Hi everyone

I’m having a very frustrating issue with surfaces when I’m simply trying to extrude from a curve. My Rhino knowledge is limited hence this topic!

This file is for the CNC machine so when I export it to Fusion 360 these strange artefacts show up. They became visible in Rhino when I turned on the color for Backface settings.

I thought it was to do with the surface normals but after flipping them it doesn’t stop the issue either. Any ideas?

I’ve tried to fix it for two days but no luck. Not ideal for when you have an approaching deadline.

 ![49](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/3/d/3d16340f972975f9c149cbc5252d3fbcafcf782d.png)

 ![04](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/9/2/9206e98a9e00909addc9e148697b56117442dab3.png)

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**Author:** ![kieffer](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/kieffer/32/599689_2.png) [@kieffer](https://discourse.mcneel.com/u/kieffer)\
**Post date:** [November 29, 2019, 6:37pm UTC](https://discourse.mcneel.com/t/surface-normals-not-extruding-correctly/92973/2 "2019-11-29T18:37:56Z")

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Hello Walid,  
It looks like you’re having not just a simple curve but the whole or part of the curve duplicated.  
You can try \_Seldup command to find duplicate.  
If it won’t work  
Try \_Explode command on the curve  
Then delete the double.

Sylvain

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**Author:** ![kieffer](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/kieffer/32/599689_2.png) [@kieffer](https://discourse.mcneel.com/u/kieffer)\
**Post date:** [November 29, 2019, 6:39pm UTC](https://discourse.mcneel.com/t/surface-normals-not-extruding-correctly/92973/3 "2019-11-29T18:39:29Z")

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(I m not in front of my computer it’s all I can see)

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**Author:** ![Walid\_Butt](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/walid_butt/32/190130_2.png) [@Walid\_Butt](https://discourse.mcneel.com/u/Walid_Butt)\
**Post date:** [November 29, 2019, 6:49pm UTC](https://discourse.mcneel.com/t/surface-normals-not-extruding-correctly/92973/4 "2019-11-29T18:49:14Z")

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Thanks for your reply! I’ve tried and no luck. I’ll explain the steps I took.

1. Extrude from curve - (the artefacts show up)
2. Explode
3. Seldup
4. Delete the selection

 ![57](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/5/d/5db40e3ef96e85f9aeead35f14c49b939a02ffc8.png)  
 ![09](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/3/c/3c1d8b38fae0151899d05eed097e194eac2e665a.png)  
 ![22](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/4/b/4bc7ef9be9a8864bd2244d506f2c1d97c9749e9d.png)  
 ![30](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/b/9/b9f5a50c9140f9bcd7a511e25c7c8c97171ce599.png)

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<div class="post-metadata">

**Author:** ![kieffer](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/kieffer/32/599689_2.png) [@kieffer](https://discourse.mcneel.com/u/kieffer)\
**Post date:** [November 29, 2019, 6:54pm UTC](https://discourse.mcneel.com/t/surface-normals-not-extruding-correctly/92973/5 "2019-11-29T18:54:12Z")

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You can try explode on the curve before extrude .  
Then manually delete the double curve. Then join the curve again and extrude.  
Good luck.  
Sylvain

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**Author:** ![Walid\_Butt](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/walid_butt/32/190130_2.png) [@Walid\_Butt](https://discourse.mcneel.com/u/Walid_Butt)\
**Post date:** [November 29, 2019, 7:02pm UTC](https://discourse.mcneel.com/t/surface-normals-not-extruding-correctly/92973/6 "2019-11-29T19:02:42Z")

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Thanks again, Sylvain. Unfortunately that hasn’t done it either. Even when I draw a completely new curve it still shows up like it is duplicated.

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<div class="post-metadata">

**Author:** ![kieffer](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/kieffer/32/599689_2.png) [@kieffer](https://discourse.mcneel.com/u/kieffer)\
**Post date:** [November 29, 2019, 7:07pm UTC](https://discourse.mcneel.com/t/surface-normals-not-extruding-correctly/92973/7 "2019-11-29T19:07:41Z")

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Ok i will look at your file tomorrow if nobody find the solution.

Sylvain

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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:** [November 29, 2019, 8:29pm UTC](https://discourse.mcneel.com/t/surface-normals-not-extruding-correctly/92973/8 "2019-11-29T20:29:30Z")

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Hi @Walid_Butt,

the display problem happens because you are working 530795.29 meters away from the world origin. Select all your geometry, type `_Move`, click on a point on the base and then enter a zero. This will move the geometry to the world origin. Then run `_RefreshShade` and all is well.

\_  
c.

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<div class="post-metadata">

**Author:** ![Walid\_Butt](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/walid_butt/32/190130_2.png) [@Walid\_Butt](https://discourse.mcneel.com/u/Walid_Butt)\
**Post date:** [November 29, 2019, 9:40pm UTC](https://discourse.mcneel.com/t/surface-normals-not-extruding-correctly/92973/9 "2019-11-29T21:40:11Z")

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Thanks @clement!! I got the file from someone else and should have thought of that.

Thank you both for helping!