Let me ask you something about extruding shell.

[jochichi]

Hello everyone,

Let me ask you something about extruding shell.
As shown in the attached figure 1, I extruded the shell of a box to the bottom direction (0, 0, -1) and it worked well.
However, extrusion for the shell of a cylinder doesn't work well as you can see the figure 2 and 3.
In Figure 3, the shell is made from all faces of the cylinder. On the other hand, the shell is made from the top circle and the side of cylinder in Figure 2.
What is going on here?? Anyone know??

Untitled.png (171.26 KiB) Viewed 596 times

[DeepSOIC]

The operation you are trying to extrude a solid (even though you've downgraded it to shell). It is not possible to do at the moment.

It is needed to first place seams on the surface of the cylinder where it is tangent to extrusion direction. There might be something like that available around the code that generates projections for drawings. Might be interesting to research.

[DeepSOIC]

See also this old thread:
https://forum.freecadweb.org/viewtopic.php?f=3&t=17054