Request for help from newbie regarding converting polyhedron to wireframe

[bonomo]

Hello!

I installed FreeCAD motivated by a need to perform a particular task. Being new, I am quite clueless as to how to do certain things.

I have a STEP file for Goldberg Polyhedron (which I think of as a hex-pent sphere). I would like to eliminate the surfaces, and leave a wireframe. I do NOT mean to to simply DISPLAY a wireframe, but to convert the object itself to a wireframe object. In principle, it should be possible to do this by editing the STEP file (as it is all text), but that would require developing a deep knowledge of the STEP file entities. I am guessing it would be easier to do this via CAD program.

1. How does one carry out this particular task (delete the faces; leave a wireframe)?
2. I find that I cannot scale the object imported from the STEP file except by creating "clone" objects. However, one apparently cannot delete the original object after copying and scaling the clones. If one uses the cloned/scaled wireframes as part of a final object that will be, eventually, 3-D printed, how does one deal with the no-longer wanted original imported object?

Thank you.
Richard Bonomo

Code: Select all

OS: macOS 10.16
Word size of FreeCAD: 64-bit
Version: 0.20.29177 (Git)
Build type: Release
Branch: (HEAD detached at 0.20)
Hash: 68e337670e227889217652ddac593c93b5e8dc94
Python 3.9.13, Qt 5.12.9, Coin 4.0.0, Vtk 9.1.0, OCC 7.5.3
Locale: C/Default (C)
Installed mods: 
  * Help 1.0.3

[edwilliams16]

Not much we can do without the STEP file.

[Willem]

Welcome to the forum.
In Freecad is also an Addin workbench for polyhedrons, so you can make a new parametric polyhedron

[thomas-neemann]

...

draft downgrade can do that. can be seen from min 0:58

https://www.youtube.com/watch?v=XKhlh5V24f4

phpBB [video]

[bonomo]

Not much we can do without the STEP file.

Oh, I can certainly supply it if someone wants to take a stab on it on my behalf, but I was first looking for some advice as to feasibility and procedure.

RB

[bonomo]

Welcome to the forum.
In Freecad is also an Addin workbench for polyhedrons, so you can make a new parametric polyhedron

Do you know if this Add-In is able to produce actual wire-frame polyhedra, or just things with faces?

Rich

[onekk]

Some things to note:

A wireframe is composed of wires, are you aware that is not a Solid?

It could be traced quite easily using a macro or Script iterating through faces and selecting wires to show.

But could be a "compound of wires" as topology seems to not be able to contain an element called wireframe as a single element with coincident edges.

As this hierarchy.

A "closed" wire could make a face
A "connected" faces could make a shell
A "closed" shell could make a Solid. (Call it maybe manifold or watertight)

So probably once you have a bunch of wires, main concern is what you want to use them for?

I'm a "normal user" so probably I'm wrong on some manner.

Regards

Carlo D.

[adrianinsaval]

Use draft downgrade to go from a solid to a face to a wire to an edge.

[bonomo]

...

draft downgrade can do that. can be seen from min 0:58

https://www.youtube.com/watch?v=XKhlh5V24f4

phpBB [video]

Thank you! Yes, the draft-->downgrade did manage to deal with the face-to-wireframe-conversion part of my query!

RB

[bonomo]

Some things to note:

A wireframe is composed of wires, are you aware that is not a Solid?

It could be traced quite easily using a macro or Script iterating through faces and selecting wires to show.

But could be a "compound of wires" as topology seems to not be able to contain an element called wireframe as a single element with coincident edges.

As this hierarchy.

A "closed" wire could make a face
A "connected" faces could make a shell
A "closed" shell could make a Solid. (Call it maybe manifold or watertight)

So probably once you have a bunch of wires, main concern is what you want to use them for?

I'm a "normal user" so probably I'm wrong on some manner.

Regards

Carlo D.

Thank you for your response. Yes, I know that a wireframe is not a solid.
I plan to use the wires as the basis for creating other surfaces (other than the original surfaces).

RB