# How to extrude on a curved surface

**URL:** <https://discourse.shapr3d.com/t/how-to-extrude-on-a-curved-surface/36354>\
**Category:** Modeling Questions\
**Created:** [February 2, 2025, 11:17am UTC](https://discourse.shapr3d.com/t/how-to-extrude-on-a-curved-surface/36354 "2025-02-02T11:17:45Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![mrplamo](https://avatars.discourse-cdn.com/v4/letter/m/ed8c4c/32.png) [@mrplamo](https://discourse.shapr3d.com/u/mrplamo)\
**Post date:** [February 2, 2025, 11:17am UTC](https://discourse.shapr3d.com/t/how-to-extrude-on-a-curved-surface/36354/1 "2025-02-02T11:17:45Z")

</div>

Hello all, new Shapr user. I am trying to cut a panel line on a curved surface, I have projected the panel onto the curved surface, however it doesn’t allow me to add negative extrude to it for some reason? Am I doing something wrong?

As you can see from the picture attached, I have successfully indented a the lower panel on a flat surface without any issues.

Any help would be greatly appreciated.

 ![Screenshot 2025-02-03 at 12.11.02 AM](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/3/4/34cad70fbae6fb8f7f979930e6eee8a5094b68bd.jpeg)

---

<div class="post-metadata">

**Author:** ![arroniow](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/arroniow/32/30268_2.png) [@arroniow](https://discourse.shapr3d.com/u/arroniow)\
**Post date:** [February 2, 2025, 3:41pm UTC](https://discourse.shapr3d.com/t/how-to-extrude-on-a-curved-surface/36354/2 "2025-02-02T15:41:20Z")

</div>

I think your problem is where your panel is across the transition between the curved surface and the flat surface.  
I get the same issue, if I draw a similar profile.  
I can surface offset as long as it does not include the transition line.

---

<div class="post-metadata">

**Author:** ![BKE](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/bke/32/31690_2.png) [@BKE](https://discourse.shapr3d.com/u/BKE)\
**Post date:** [February 2, 2025, 6:03pm UTC](https://discourse.shapr3d.com/t/how-to-extrude-on-a-curved-surface/36354/3 "2025-02-02T18:03:42Z")

</div>

I just tried, could not make it to fail.

 ![2025-02-02 18.52.10](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/f/6/f62e945d6c5e372a3b20bbfe770293713a086cc6.jpeg)

In some more complex situations when going _all_ _way_ _trough_ fails I found that a fallback to create a body and then subtract may succeed.

I always try to make clean cuts and merges, avoiding creating (to) complex result. In the example the sketch unnecessary tangens the surface could this make a difference?

---

<div class="post-metadata">

**Author:** ![mrplamo](https://avatars.discourse-cdn.com/v4/letter/m/ed8c4c/32.png) [@mrplamo](https://discourse.shapr3d.com/u/mrplamo)\
**Post date:** [February 2, 2025, 7:59pm UTC](https://discourse.shapr3d.com/t/how-to-extrude-on-a-curved-surface/36354/4 "2025-02-02T19:59:01Z")

</div>

Thanks for the reply, I seem to have figured how to get it to work, I think I may have messed up the step while doing the projection, initially the projected faces was done one by one, have just realised you can actually project onto 3 faces simultaneously and that seems to have solved the issue.

 ![Screenshot 2025-02-03 at 8.56.29 AM](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/2/1/21849fba62809c8475ca3371863490eaeaf4e820.jpeg)

---

<div class="post-metadata">

**Author:** ![arroniow](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/arroniow/32/30268_2.png) [@arroniow](https://discourse.shapr3d.com/u/arroniow)\
**Post date:** [February 3, 2025, 1:35pm UTC](https://discourse.shapr3d.com/t/how-to-extrude-on-a-curved-surface/36354/5 "2025-02-03T13:35:02Z")

</div>

I did the same sketch and solid again, and this time it worked no problem.  
🤣