Welcome to the Onshape forum! Ask questions and join in the discussions about everything Onshape.
First time visiting? Here are some places to start:- Looking for a certain topic? Check out the categories filter or use Search (upper right).
- Need support? Ask a question to our Community Support category.
- Please submit support tickets for bugs but you can request improvements in the Product Feedback category.
- Be respectful, on topic and if you see a problem, Flag it.
If you would like to contact our Community Manager personally, feel free to send a private message or an email.
Cannot shell a piece

Hi, gents. I need help with this part, which I want to shell to 1-1.5mm inwards, and for some reason, when I select any face to remove, I go red. I have been trying for several days, but I have to give up and ask for help to understand what is causing this problem and how to solve it.
Here is the link to the document: https://cad.onshape.com/documents/4b8c65ed7dc9cd2f211706af/w/796e1ff6014797bbeb5e8a68/e/0076fc3f3f4a0ffdc98f1cb3?renderMode=0&uiState=68764e453ccb652573305f15
The tab I am working on is "Cowl 11 Copy1 Copy 1"
Comments
Using sketch 38 as a guide in your loft is creating this little wrinkle.
That will cause the Shell to fail. Get ride of that guide and the loft is much smoother and is able to be shelled.
I understand that, but I need 38 to give the part a shape. The point is that I do not know if the problem is the shape of 38 or the plane it is located on. I had this kind of problem before, although with parallel ends and which made it easy to choose a position to locate the guide plane, but in this case, I tried several positions and failed. Is there a method to choose where to locate the guide plane?
If you need sketch 38, just be careful to not make sharp corners. See below. That will be a tough guide for the loft to follow.
I replaced it with a spline with a couple of pierce constraints and it works better.
Great. I will try that. Thank you for your comments.