Spherical Calotte with 3 Walls

[atzensepp]

I would like to have a calotte with a mercedes-star-like structure in it. Currently I am on the sketch-and-pad-trip. But this might be a "wood way". Maybe a polar-array would be more apropriate. The strucutre should look similar to the image attached but without the grates on the lower side and the residual grate on the left side.
The Object should be parametrized with:
- Radius of outer sphere
- Radius of inner sphere
- Cut-position of spheres (z) for calotte cut
- Thickness of the inner walls
- Angle of inclination of the inner walls (3 times the same)
(The inner walls shall have an angle of 120 Degrees)
(Later in far future I want to cut a grate into the inner walls and a hole perpendicular to the walls)
How can I do this? Help appreciated.

[atzensepp]

Ok, I did it with the polar arrangement. Unfortunately the geometries from sphere and walls are de-coupled.

[bejant]

Ok, I did it with the polar arrangement. Unfortunately the geometries from sphere and walls are de-coupled

Now all you need to do is use the Part WB > Boolean Union:

on Cut001 and Array to Fusion these two separate pieces together.

[ektus]

I did a quick take with PartDesign. Editing the first sketch, it's possible to alter the Calotte parameters, and likewise editing the second sketch for the thickness of the wall.

star.png (63.32 KiB) Viewed 1937 times

Regards
Ektus.

OS: Windows 7
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.15.4666 (Git)
Branch: releases/FreeCAD-0-15
Hash: be823acda289b9354226b3229d98ca0ac9352267
Python version: 2.7.8
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

[atzensepp]

Hej bejant and ektus, thank you for your advices!
Now I would like to change the shpere radii or cut height and have FreeCad calculate the geometry of the triangles automatically.
If one could assign variables to geometric properties and refer to them by a formula in another geometry this would be possible.
With a python script it should be possible to do such a calculation. But one has to invoke the script manually. It would be nice if this update could be done automatically.

[atzensepp]

Heureka, it is possible with FreeCAD board tools!
Create a 120-deg Sphere-Shell Segment and use Sketcher to draw the walls, pad it symmetrically and make a 3-fold polar arrangement.

[DeepSOIC]

Here's my =) made just when you posted

[atzensepp]

Hi DeepSOIC,

Here's my =) made just when you posted

That's it! With the "Revolution" it is not necessary to use the odd cutting operations between spheres and cube!