exporting parts of an object

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exporting parts of an object

kitwallace
I've cut a cube into two halves [ using difference() with a hulled sequenced of thin hulled cones from centre to points on the path across the cube surface]

 

 I'd like to separate the two halves to export separately.  Is that possible in OpenSCAD?  if not what would you use on the STL to do this?

Kit

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Re: exporting parts of an object

Whosawhatsis
It looks/sounds like you've created a parting line, but that both pieces of the original (single) cube remain. Is that right?

Assuming the two ended up fully-separated pieces (not sharing any points), you can probably export one STL, then use something like Meshmixer or Cura's Mesh Tools plugin to separate them and save them as separate files.

A better way to do it would be to create the cube and a "cutting body". Something that you can subtract from the cube to get just ONE of your pieces. Using difference, you can export that one part, then you can change the operation to intersection to get the other part.

Of course, it also appears that your two halves are intended to be identical to one another, so you could just export one half and make two copies of it...
On Feb 25, 2021, 00:05 -0800, kitwallace <[hidden email]>, wrote:
I've cut a cube into two halves [ using difference() with a hulled sequenced of thin hulled cones from centre to points on the path across the cube surface]

 

 I'd like to separate the two halves to export separately.  Is that possible in OpenSCAD?  if not what would you use on the STL to do this?

Kit

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Re: exporting parts of an object

kitwallace
 Yes exactly - this is the parting surface



other surfaces are a bit more complex



and I dont see yet how to form a 'cutting body' but its a thought.

I'll give meshmixer a whirl





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Re: exporting parts of an object

Ronaldo
As you know the geometric data of the points on the cube surface and you also know the geometry of the cube, it is conceptually possible (although not an easy task) to compute the geometry of the two connected components, the two parts you need, and generate a polyhedron for each one.

Em qui., 25 de fev. de 2021 às 08:53, kitwallace <[hidden email]> escreveu:
 Yes exactly - this is the parting surface



other surfaces are a bit more complex



and I dont see yet how to form a 'cutting body' but its a thought.

I'll give meshmixer a whirl





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Re: exporting parts of an object

mondo
In reply to this post by kitwallace

H Kit,

If you can export it as an stl, then I'm pretty sure Meshlab can remove bits you don't want (and in my experience bits I do want too XD)  Unfortunately, there is no 'undo' in ~Meshlabe, but other than that it will do most things to stl files.

Best wishes,

Ray

On 25/02/2021 08:04, kitwallace wrote:
I've cut a cube into two halves [ using difference() with a hulled sequenced of thin hulled cones from centre to points on the path across the cube surface]

 

 I'd like to separate the two halves to export separately.  Is that possible in OpenSCAD?  if not what would you use on the STL to do this?

Kit

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Re: exporting parts of an object

kitwallace
In reply to this post by Ronaldo
Ronaldo - Yes of course you are right  - I'd just hacked the surface using hull() but it should be a polyhedron anyway -  computing a half would be a bit head-scratching - the solid being cut is a generic polyhedron.

I now recall that Meshmixer doesnt like my rather ancient graphics card

However I've just discovered slic3r does it perfectly! - load the stl , click split !



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