<p>Only proper solution that's worked for me on the .stl level like this is manually deleting and patching the triangles in FreeCAD's Mesh Design.  It's usually time consuming, but there are 3d scans and the like that just cannot be modified correctly without fixing the mesh (either before or after the mod).</p>

CC BY-SA 4.0
2020-08-28T07:45:10.037Z
2020-08-28T07:45:10.037Z
Abel
<p>I suspect that your method to create the hole for the pins may not be consistent with the modeling practice that FreeCad and other programs of this nature require.</p>

<p>Consider the following:</p>

<p>Import your base shape.
Create a second shape that matches the hole you wish to create. It must be a solid object, not a plane or other single surface item.</p>

<p>Consult one of the <a href="https://wiki.freecadweb.org/Basic_modeling_tutorial" rel="nofollow noreferrer">many FreeCad tutorials</a> that present the method to use next, that is to place the shape to be subtracted in the desired location, then perform a Boolean operation involving both objects. In the linked tutorial, it's referred to as a cut, which is an accurate description.</p>

<p>Performing this action will create a surface where the two objects intersect, removing the smaller one, leaving a solid, rather than a zero thickness surface. </p>

<p>You would then create and place the cylinders in a manner consistent with the original model.</p>

CC BY-SA 4.0
2020-03-29T19:37:28.113Z
That is exactly what I did. It seems this still leaves me with a non watertight result.
Chry007
CC BY-SA 4.0
2020-03-31T15:21:22.010Z
@Chry007 looks like you'll have to track down defects in the FreeCad model, and check the direction of surface normals, and so on.
Carl Witthoft
CC BY-SA 4.0
2020-03-29T18:53:03.767Z
2020-03-29T18:53:03.767Z
fred_dot_u
<p>I am trying to import an STL file, I created in FreeCAD. It has a hole in the hull of the object and behind that hole there are two pins inside the object (see attached FreeCAD screenshot).</p>

<p>When I import the STL in Cura, there are no walls around the whole object where there is the hole in the hull (see attached Cura screenshots). However the wall and the hole are visible in light grey, Cura just doesn't print it.</p>

<p>Update:</p>

<p> I understand the problem. It's not a watertight solid. I found a way to import it somewhat fine using meshmixer to create a hollow with an offset which makes the outer Hull actually have a thickness to it. Now the problem is, that's not really what I want. The result in cura now can't be printed with infill since the actual inside of the model is only within the walls. Also cura sees both sides of the wall as outer Perimeter. I understand the problem but actually am looking for a way to just prevent printing part of the regular model's wall.. In other words: I would basically like to set the whall line count to zero in that particular area. I just tried to use the support blocker and "Modify settings for overlap" but that doesn't do anything.</p>

<p>CURA:</p>

<p><a href="https://i.sstatic.net/hrCAY.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/hrCAY.png" alt="enter image description here"></a>
 <a href="https://i.sstatic.net/7ETuW.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/7ETuW.png" alt="enter image description here"></a></p>

<p>FreeCAD:
<a href="https://i.sstatic.net/Lddxh.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Lddxh.png" alt="enter image description here"></a></p>

CC BY-SA 4.0
2020-03-29T16:16:43.473Z
Is the wall a zero-thickness construct?
fred_dot_u
CC BY-SA 4.0
2020-03-29T16:21:52.467Z
Yes it is. I figured that might be the problem, but I can't find a way to solve it. The base model, that I import to cut the whole into is an stl and I basically just need a way to have a hole in the object's hull and the two pins behind it.
Chry007
CC BY-SA 4.0
2020-03-30T04:02:16.067Z
the object is not a watertight solid, which results in misslicing.
Trish
CC BY-SA 4.0
2020-03-30T08:24:42.107Z
I understand the problem. It's not a watertight solid. I found a way to import it somewhat fine using meshmixer to create a hollow with an offset which makes the outer Hull actually have a thickness to it. Now the problem is, that's not really what I want. The result in cura now can't be printed with infill since the actual inside of the model is only within the walls. Also cura sees both sides of the wall as outer Perimeter. I understand the problem but actually am looking for a way to just prevent printing part of the regular model's wall..
Chry007
<ultimaker-cura><slicing><freecad>
Cura imports FreeCAD stl wrong
Chry007
# Cura imports FreeCAD stl wrong

(Asked by: username_0 on 2020-03-29)

I am trying to import an STL file, I created in FreeCAD. It has a hole in the hull of the object and behind that hole there are two pins inside the object (see attached FreeCAD screenshot).

When I import the STL in Cura, there are no walls around the whole object where there is the hole in the hull (see attached Cura screenshots). However the wall and the hole are visible in light grey, Cura just doesn't print it.

Update:

 I understand the problem. It's not a watertight solid. I found a way to import it somewhat fine using meshmixer to create a hollow with an offset which makes the outer Hull actually have a thickness to it. Now the problem is, that's not really what I want. The result in cura now can't be printed with infill since the actual inside of the model is only within the walls. Also cura sees both sides of the wall as outer Perimeter. I understand the problem but actually am looking for a way to just prevent printing part of the regular model's wall.. In other words: I would basically like to set the whall line count to zero in that particular area. I just tried to use the support blocker and "Modify settings for overlap" but that doesn't do anything.

CURA:

[![enter image description here](https://i.sstatic.net/hrCAY.png)](https://i.sstatic.net/hrCAY.png)
[![enter image description here](https://i.sstatic.net/7ETuW.png)](https://i.sstatic.net/7ETuW.png)

FreeCAD:
[![enter image description here](https://i.sstatic.net/Lddxh.png)](https://i.sstatic.net/Lddxh.png)

**Tags:** ultimaker-cura, slicing, freecad
> **Comments:**
> **username_1**: Is the wall a zero-thickness construct?  
> **username_0**: Yes it is. I figured that might be the problem, but I can't find a way to solve it. The base model, that I import to cut the whole into is an stl and I basically just need a way to have a hole in the object's hull and the two pins behind it.  
> **username_2**: the object is not a watertight solid, which results in misslicing.  
> **username_0**: I understand the problem. It's not a watertight solid. I found a way to import it somewhat fine using meshmixer to create a hollow with an offset which makes the outer Hull actually have a thickness to it. Now the problem is, that's not really what I want. The result in cura now can't be printed with infill since the actual inside of the model is only within the walls. Also cura sees both sides of the wall as outer Perimeter. I understand the problem but actually am looking for a way to just prevent printing part of the regular model's wall..  

---

## 2 answers

### Answer by username_3 on 2020-08-28. Score: 1

Only proper solution that's worked for me on the .stl level like this is manually deleting and patching the triangles in FreeCAD's Mesh Design. It's usually time consuming, but there are 3d scans and the like that just cannot be modified correctly without fixing the mesh (either before or after the mod).


---

### Answer by username_1 on 2020-03-29. Score: 1

I suspect that your method to create the hole for the pins may not be consistent with the modeling practice that FreeCad and other programs of this nature require.

Consider the following:

Import your base shape.
Create a second shape that matches the hole you wish to create. It must be a solid object, not a plane or other single surface item.

Consult one of the [many FreeCad tutorials](https://wiki.freecadweb.org/Basic_modeling_tutorial) that present the method to use next, that is to place the shape to be subtracted in the desired location, then perform a Boolean operation involving both objects. In the linked tutorial, it's referred to as a cut, which is an accurate description.

Performing this action will create a surface where the two objects intersect, removing the smaller one, leaving a solid, rather than a zero thickness surface.

You would then create and place the cylinders in a manner consistent with the original model.

> **Comments:**
> **username_0**: That is exactly what I did. It seems this still leaves me with a non watertight result.  
> **username_4**: @Chry007 looks like you'll have to track down defects in the FreeCad model, and check the direction of surface normals, and so on.  

---

