Empathy List Archives

K

kitwallace

Thu, Feb 25, 2021 8:04 AM

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]

http://forum.openscad.org/file/t229/split-cube.png

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

--
Sent from: http://forum.openscad.org/

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] <http://forum.openscad.org/file/t229/split-cube.png> 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 -- Sent from: http://forum.openscad.org/

W

Whosawhatsis

Thu, Feb 25, 2021 8:17 AM

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 kit.wallace@gmail.com, 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
Sent from the OpenSCAD mailing list archive at Nabble.com.

OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org

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 <kit.wallace@gmail.com>, 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 > Sent from the OpenSCAD mailing list archive at Nabble.com. > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org

K

kitwallace

Thu, Feb 25, 2021 8:53 AM

Yes exactly - this is the parting surface

http://forum.openscad.org/file/t229/cube-surface.png

other surfaces are a bit more complex

http://forum.openscad.org/file/t229/icoso-surface.png

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

I'll give meshmixer a whirl

--
Sent from: http://forum.openscad.org/

Yes exactly - this is the parting surface <http://forum.openscad.org/file/t229/cube-surface.png> other surfaces are a bit more complex <http://forum.openscad.org/file/t229/icoso-surface.png> and I dont see yet how to form a 'cutting body' but its a thought. I'll give meshmixer a whirl -- Sent from: http://forum.openscad.org/

RP

Ronaldo Persiano

Thu, Feb 25, 2021 2:51 PM

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 kit.wallace@gmail.com
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

Sent from the OpenSCAD mailing list archive http://forum.openscad.org/
at Nabble.com.

OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org

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 <kit.wallace@gmail.com> 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 > > > > > ------------------------------ > Sent from the OpenSCAD mailing list archive <http://forum.openscad.org/> > at Nabble.com. > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >

RW

Ray West

Thu, Feb 25, 2021 3:39 PM

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

Sent from the OpenSCAD mailing list archive
http://forum.openscad.org/ at Nabble.com.

OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org

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 > ------------------------------------------------------------------------ > Sent from the OpenSCAD mailing list archive > <http://forum.openscad.org/> at Nabble.com. > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org

K

kitwallace

Thu, Feb 25, 2021 4:22 PM

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 !

--
Sent from: http://forum.openscad.org/

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 ! -- Sent from: http://forum.openscad.org/

discuss@lists.openscad.org

exporting parts of an object

Kit