need a non-STL file format

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need a non-STL file format

jon_bondy

We are trying to get a quote for injection molding of a part.  We were told that they needed STEP files, so I converted the STL into a STEP, but now they say that this is inadequate.  Here is what they have to say.  Any thoughts about how to satisfy them (short of paying someone to re-design the part from scratch in a CAD program)?  Is this a problem that other OpenSCAD users have faced, or expect to face in the future?

Jon


We received your request for quote, but we cannot process an STL-based or mesh file. We require surface model files, generated directly from a native CAD format. Saving a part in STL format deletes some of the information that we require. We can work with the following file formats: native SolidWorks (.sldprt) and ProE (.prt) files; files from other CAD systems output in IGES (.igs), STEP (.stp), Parasolid (.x_t or .x_b), ACIS (.sat); and AutoCAD (.ipt and .dwg, 3D only).


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Re: need a non-STL file format

fred_dot_u
As I have SolidWorks, I searched and found a set of simple instructions to accomplish your task. SW will import an STL file which is converted to solid body during the import process. From there, it's a simple matter to either save it as the .SLDPRT format or any other supported type.

I also found during this search a set of similar steps to be performed using FreeCAD, which one might consider if the output format of that program meets your requirements.

If you seen Blender or Meshmixer displays of a part, you'd easily recognize the SW conversion, although I suspect the triangles of SW, Blender and Meshmixer are mostly ignored by the vendor for your application.

https://www.google.com/#q=convert+stl+to+solidworks
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Re: need a non-STL file format

Hypher
In reply to this post by jon_bondy
My best luck with getting STEP files from OpenSCAD is to first import the SCAD file into FreeCAD and then export to STEP. Note that FreeCAD does not support some features of OpenSCAD, and that it often takes a fair bit of work to get things working right with FreeCAD.

>From my experience:
  1. You absolutely cannot use these modules: offset, minkowski, hull or projection find another way to model things if you do.
  2. Try to do as much as possible in 2d and then extrude into 3d. This is better for native OpenSCAD work as well, as it's faster and doesn't have issues with tolerances. For example, instead of difference() { cube([10,10,10]); translate([2,2,-.5]) cube([6,6,11]); } do linear_extrude(10) difference() { square([10,10]); translate([2,2]) square([6,6]); }
  3. Start slowly with your exporting and importing into FreeCAD. Do it one part or module at a time, starting with something simple that works. If you have many parts, export them one at a time, starting with the simple ones.
  4. FreeCAD can take a very long time to import an OpenSCAD model. Don't assume that it has crashed just because it takes 10 minutes with no progress indicator.

Best of luck.

~ Yona

July 26, 2016 at 14:20

We are trying to get a quote for injection molding of a part.  We were told that they needed STEP files, so I converted the STL into a STEP, but now they say that this is inadequate.  Here is what they have to say.  Any thoughts about how to satisfy them (short of paying someone to re-design the part from scratch in a CAD program)?  Is this a problem that other OpenSCAD users have faced, or expect to face in the future?

Jon


We received your request for quote, but we cannot process an STL-based or mesh file. We require surface model files, generated directly from a native CAD format. Saving a part in STL format deletes some of the information that we require. We can work with the following file formats: native SolidWorks (.sldprt) and ProE (.prt) files; files from other CAD systems output in IGES (.igs), STEP (.stp), Parasolid (.x_t or .x_b), ACIS (.sat); and AutoCAD (.ipt and .dwg, 3D only).

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Re: need a non-STL file format

jon_bondy
In reply to this post by fred_dot_u

Thanks.  I used the FreeCAD procedure to produce the STEP file that the vendor says they cannot use. If you read what they say, it reads, in part, "[must be] generated directly from a native CAD format. Saving a part in STL format deletes some of the information that we require."

My point is that I may not be the only person who will eventually trip on this step.

Jon


On 7/26/2016 5:49 PM, fred_dot_u wrote:
As I have SolidWorks, I searched and found a set of simple instructions to
accomplish your task. SW will import an STL file which is converted to solid
body during the import process. From there, it's a simple matter to either
save it as the .SLDPRT format or any other supported type. 

I also found during this search a set of similar steps to be performed using
FreeCAD, which one might consider if the output format of that program meets
your requirements.

If you seen Blender or Meshmixer displays of a part, you'd easily recognize
the SW conversion, although I suspect the triangles of SW, Blender and
Meshmixer are mostly ignored by the vendor for your application.

https://www.google.com/#q=convert+stl+to+solidworks



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Re: need a non-STL file format

fred_dot_u
In reply to this post by Hypher
Intrigued about the reference to not using hull(), I imported my recent 3d print file into SW. I've found hull() to be invaluable for conversions of shapes along a linear reference. I needed a vacuum manifold to lie flat on a surface and the model I created fit the bill perfectly. I would not be able to have this injection molded, as per the OP, but it looks even cooler in SW than it did in OpenSCAD:

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Re: need a non-STL file format

jon_bondy
In reply to this post by Hypher

I had no idea that FreeCAD could import OpenSCAD.  Of course, as it turns out, it cannot.  You need to download some DXF libraries.  And the procedure to do that is ASTONISHINGLY long and complex.  I gave up.  Maybe some other day.

Thanks for explaining that this alternative exists: I did not know about it!

Jon


On 7/26/2016 6:14 PM, Yona Appletree wrote:
My best luck with getting STEP files from OpenSCAD is to first import the SCAD file into FreeCAD and then export to STEP. Note that FreeCAD does not support some features of OpenSCAD, and that it often takes a fair bit of work to get things working right with FreeCAD.

>From my experience:
  1. You absolutely cannot use these modules: offset, minkowski, hull or projection find another way to model things if you do.
  2. Try to do as much as possible in 2d and then extrude into 3d. This is better for native OpenSCAD work as well, as it's faster and doesn't have issues with tolerances. For example, instead of difference() { cube([10,10,10]); translate([2,2,-.5]) cube([6,6,11]); } do linear_extrude(10) difference() { square([10,10]); translate([2,2]) square([6,6]); }
  3. Start slowly with your exporting and importing into FreeCAD. Do it one part or module at a time, starting with something simple that works. If you have many parts, export them one at a time, starting with the simple ones.
  4. FreeCAD can take a very long time to import an OpenSCAD model. Don't assume that it has crashed just because it takes 10 minutes with no progress indicator.

Best of luck.

~ Yona

July 26, 2016 at 14:20

We are trying to get a quote for injection molding of a part.  We were told that they needed STEP files, so I converted the STL into a STEP, but now they say that this is inadequate.  Here is what they have to say.  Any thoughts about how to satisfy them (short of paying someone to re-design the part from scratch in a CAD program)?  Is this a problem that other OpenSCAD users have faced, or expect to face in the future?

Jon


We received your request for quote, but we cannot process an STL-based or mesh file. We require surface model files, generated directly from a native CAD format. Saving a part in STL format deletes some of the information that we require. We can work with the following file formats: native SolidWorks (.sldprt) and ProE (.prt) files; files from other CAD systems output in IGES (.igs), STEP (.stp), Parasolid (.x_t or .x_b), ACIS (.sat); and AutoCAD (.ipt and .dwg, 3D only).

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Re: need a non-STL file format

Hypher
In reply to this post by jon_bondy
Sorry, I left out something important. When you export into FreeCAD, you export from OpenSCAD as CSG, not STL. There is a huge difference between these, and using CSG will result in native CAD primitives that can be used.

July 26, 2016 at 15:23

Thanks.  I used the FreeCAD procedure to produce the STEP file that the vendor says they cannot use. If you read what they say, it reads, in part, "[must be] generated directly from a native CAD format. Saving a part in STL format deletes some of the information that we require."

My point is that I may not be the only person who will eventually trip on this step.

Jon


On 7/26/2016 5:49 PM, fred_dot_u wrote:

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July 26, 2016 at 14:20

We are trying to get a quote for injection molding of a part.  We were told that they needed STEP files, so I converted the STL into a STEP, but now they say that this is inadequate.  Here is what they have to say.  Any thoughts about how to satisfy them (short of paying someone to re-design the part from scratch in a CAD program)?  Is this a problem that other OpenSCAD users have faced, or expect to face in the future?

Jon


We received your request for quote, but we cannot process an STL-based or mesh file. We require surface model files, generated directly from a native CAD format. Saving a part in STL format deletes some of the information that we require. We can work with the following file formats: native SolidWorks (.sldprt) and ProE (.prt) files; files from other CAD systems output in IGES (.igs), STEP (.stp), Parasolid (.x_t or .x_b), ACIS (.sat); and AutoCAD (.ipt and .dwg, 3D only).

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Re: need a non-STL file format

Hypher
In reply to this post by jon_bondy
P.S. Here is a tutorial on this from the FreeCAD folks: http://www.freecadweb.org/wiki/index.php?title=Import_OpenSCAD_code

July 26, 2016 at 15:23

Thanks.  I used the FreeCAD procedure to produce the STEP file that the vendor says they cannot use. If you read what they say, it reads, in part, "[must be] generated directly from a native CAD format. Saving a part in STL format deletes some of the information that we require."

My point is that I may not be the only person who will eventually trip on this step.

Jon


On 7/26/2016 5:49 PM, fred_dot_u wrote:

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July 26, 2016 at 14:20

We are trying to get a quote for injection molding of a part.  We were told that they needed STEP files, so I converted the STL into a STEP, but now they say that this is inadequate.  Here is what they have to say.  Any thoughts about how to satisfy them (short of paying someone to re-design the part from scratch in a CAD program)?  Is this a problem that other OpenSCAD users have faced, or expect to face in the future?

Jon


We received your request for quote, but we cannot process an STL-based or mesh file. We require surface model files, generated directly from a native CAD format. Saving a part in STL format deletes some of the information that we require. We can work with the following file formats: native SolidWorks (.sldprt) and ProE (.prt) files; files from other CAD systems output in IGES (.igs), STEP (.stp), Parasolid (.x_t or .x_b), ACIS (.sat); and AutoCAD (.ipt and .dwg, 3D only).

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Re: need a non-STL file format

Alan Cox
In reply to this post by jon_bondy
On Tue, 26 Jul 2016 18:23:01 -0400
jon <[hidden email]> wrote:

> Thanks.  I used the FreeCAD procedure to produce the STEP file that the
> vendor says they cannot use. If you read what they say, it reads, in
> part, "[must be] generated directly from a native CAD format. Saving a
> part in STL format deletes some of the information that we require."
>
> My point is that I may not be the only person who will eventually trip
> on this step.

Another point.

If there is an easy way to do it, then a competent tooling producer will
know how to do it and accept STL as input 8)

Alan

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Re: need a non-STL file format

jon_bondy
In reply to this post by Hypher

Yona:

You have been very helpful, but FreeCAD keeps telling me that the DXF libraries need to be installed (even when opening a CSG file), and that appears to be a Herculean task.  I do not understand why the automatic install fails, but it does.

Jon


On 7/26/2016 6:38 PM, Yona Appletree wrote:
Sorry, I left out something important. When you export into FreeCAD, you export from OpenSCAD as CSG, not STL. There is a huge difference between these, and using CSG will result in native CAD primitives that can be used.


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Re: need a non-STL file format

Neon22
The message they are really trying to express is this:
- a triangulated mesh file is not able to be used by them to machine your part.
- they want a solid model constructed from solid primitives.
Of course you should validate with them that this is correct.

I believe Solidworks might have such a tool but AFAIK it's an open problem to convert an arbitrary mesh to a booleaned set of solid primitives. AFAIK this hasn't been solved yet. But I'm happy to accept solidworks has a solution.

So what they are saying they want - is a model in STEP format comprised of solids.
OpenSCAD has no STEP exporter.
FreeCAD - do not know but suspect you would have to remodel in this, or any of the other suitable CAD packages.

The FreeCAD openSCAD importer does look like it does the right thing but as other commenters have said - you can't use the more idiosyncratic prims like hull. Must be straight solid prims and boolean ops only.

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Re: need a non-STL file format

Neon22
OK. just tried the procedure using FreeCAD - works remarkably well.
1. Loaded the openscad file into openscad and saved as csg.
2. Downloaded freecad 0.15 - I'm on windows - can't speak for other platforms.
3. Followed instructions here: http://www.freecadweb.org/wiki/index.php?title=Import_OpenSCAD_code
4. started FreeCAD 0.15
4. Edited preferences and under Openscad - told it where the openscad binary was.
5. Changed to openscad workbench
6. Opened the csg file previously saved
7. appears as a nice set of primitives (I had a nicely behaved file made out of cubes, using difference and mirror ops)
8. Exported as STP file

Resulting stp file is indeed made of primitives and not a polygon mesh.
High probability this would convert OK.

@jon_bondy if you can't get it to work - PM me and I'll have a go for you.
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Re: need a non-STL file format

jon_bondy
Thanks SO much!  I will get back to you once I've had time to repeat
your steps!


On 7/26/2016 8:18 PM, Neon22 wrote:

> OK. just tried the procedure using FreeCAD - works remarkably well.
> 1. Loaded the openscad file into openscad and saved as csg.
> 2. Downloaded freecad 0.15 - I'm on windows - can't speak for other
> platforms.
> 3. Followed instructions here:
> http://www.freecadweb.org/wiki/index.php?title=Import_OpenSCAD_code
> 4. started FreeCAD 0.15
> 4. Edited preferences and under Openscad - told it where the openscad binary
> was.
> 5. Changed to openscad workbench
> 6. Opened the csg file previously saved
> 7. appears as a nice set of primitives (I had a nicely behaved file made out
> of cubes, using difference and mirror ops)
> 8. Exported as STP file
>
> Resulting stp file is indeed made of primitives and not a polygon mesh.
> High probability this would convert OK.
>
> @jon_bondy if you can't get it to work - PM me and I'll have a go for you.
>
>
>
> --
> View this message in context: http://forum.openscad.org/need-a-non-STL-file-format-tp17989p18001.html
> Sent from the OpenSCAD mailing list archive at Nabble.com.
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Re: need a non-STL file format

kintel
Administrator

> On Jul 26, 2016, at 20:24, jon <[hidden email]> wrote:
>
> Thanks SO much!  I will get back to you once I've had time to repeat your steps!
>
Please keep us updated!
It would be interesting to learn what specific subset of STEP they support.
If you know anything about which software they use on their end to import these files, we could take note of that in future documentation.

 -Marius


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Re: need a non-STL file format

arhi
In reply to this post by jon_bondy
On 7/27/2016 2:24 AM, jon wrote:
> Thanks SO much!  I will get back to you once I've had time to repeat
> your steps!

freecad is under development so best way to help, if your file is not
loading properly when you open it in freecad is to report a bug :)

as for why that company want "real" solid model (when you convert mesh
to solid it often stays mesh only in solid file format, but it is not a
solid) is that when you give them a mesh (irrelevant in what file
format) their software can't extract properly volume, problematic areas
(too small to "work", impossible to remove from mold etc..), as all
functions expect a proper solid and not a mesh. Some apps do work with
mesh too but most require proper solid (just like old cam sw's didn't
want to accept mesh and required solids)

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Re: need a non-STL file format

nophead
What is the definition of a "real" solid here? Does OpenScad even have them to export? It works with polyhedra and when they are manifold the STL files doesn't lose anything anyway.

On 19 September 2016 at 05:00, Bogdan Kecman <[hidden email]> wrote:
On 7/27/2016 2:24 AM, jon wrote:
> Thanks SO much!  I will get back to you once I've had time to repeat
> your steps!

freecad is under development so best way to help, if your file is not
loading properly when you open it in freecad is to report a bug :)

as for why that company want "real" solid model (when you convert mesh
to solid it often stays mesh only in solid file format, but it is not a
solid) is that when you give them a mesh (irrelevant in what file
format) their software can't extract properly volume, problematic areas
(too small to "work", impossible to remove from mold etc..), as all
functions expect a proper solid and not a mesh. Some apps do work with
mesh too but most require proper solid (just like old cam sw's didn't
want to accept mesh and required solids)

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Re: need a non-STL file format

cacb
On 2016-09-19 08:52, nop head wrote:
> What is the definition of a "real" solid here?

FreeCAD uses OpenCasCade I think. I am guessing a "real" solid would
mean a native CAD geometry/topology model with separate geometry
(point,curve,surface and more) and topology (vertex,edge,face,body and
more), like you have in OpenCasCade or ACIS. I have used both in the
past, but I am more familiar with ACIS. I guess in practical terms a
"real" solid could be exported like a STEP (AP214?) or an ACIS .sat
file. The difference from OpenSCAD is that these model representations
are not polyhedron based. In ACIS a solid would correspond to a BODY or
a LUMP.

> Does OpenScad even have them to export?

Not a chance, except if you go the indirect route via .csg as previously
discussed and export primitives only. Then the receiving end can build
the geometry/topology from those. The problem is that you are limited to
a few primitives only, and things like hull or minkowski would
definitely break it. In ACIS you have

http://p.blog.csdn.net/images/p_blog_csdn_net/feijj2002_/153762/o_solid17.bmp

or rather, in more realistic detail

http://images.cppblog.com/cppblog_com/eryar/Windows-Live-Writer/Topology-and-Geometry-in-OpenCascade-Top_D29F/wps_clip_image-8073_thumb.png?_=1993008393


> It works with polyhedra and when they are manifold the
> STL files doesn't lose anything anyway.

It will not work in general to convert from any mesh based
representation into OpenCasCade or ACIS, as the model representations
are very different.

Carsten Arnholm

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Re: need a non-STL file format

Neon22
what is meant (generally) by solid model is that it is made from
primitives which are mathematical entities. A collection of polygons
does not fall into this def. Here's why they do this:

 From a pragmatic point of view its because of this:
- the solids and surfaces that a CAD system uses need to be able to have
a number of operators performed on them which are continuous and give
'clean' results. (Yes I'm using all sorts of uselessly vague words. Try
to grasp what I'm getting at.)
E.g.  Calculating a tangent so the forces on a tool path can be
calculated. A collection of polygons does not have a "smooth" (yes I
know) result so interpolation algorithms and other aspects give ill
defined results in some circumstances.

So the CAD systems have defined a number of primitives which have well
exercised and resolved solutions to all of the manipulations they want
to do. OpenCASCADE, Solidworks, ProE, ACIS have what they refer to as
solids kernels which resolve all questions for interesctions etc.

Polygons make poor long path trajectories for entities like an Arc
because they approximate an Arc, whereas one of the Arc representations
will produce a smooth curve at CAM toolpath time, or Forces at
simulation time.

so forget words like "real" solids etc etc. Its a pragmatic reduced set
of well exercised parametric, math based, solid curve and surface
representations that they need.


On 9/19/2016 7:42 PM, [hidden email] wrote:

> On 2016-09-19 08:52, nop head wrote:
>> What is the definition of a "real" solid here?
>
> FreeCAD uses OpenCasCade I think. I am guessing a "real" solid would
> mean a native CAD geometry/topology model with separate geometry
> (point,curve,surface and more) and topology (vertex,edge,face,body and
> more), like you have in OpenCasCade or ACIS. I have used both in the
> past, but I am more familiar with ACIS. I guess in practical terms a
> "real" solid could be exported like a STEP (AP214?) or an ACIS .sat
> file. The difference from OpenSCAD is that these model representations
> are not polyhedron based. In ACIS a solid would correspond to a BODY
> or a LUMP.
>
>> Does OpenScad even have them to export?
>
> Not a chance, except if you go the indirect route via .csg as
> previously discussed and export primitives only. Then the receiving
> end can build the geometry/topology from those. The problem is that
> you are limited to a few primitives only, and things like hull or
> minkowski would definitely break it. In ACIS you have
>
> http://p.blog.csdn.net/images/p_blog_csdn_net/feijj2002_/153762/o_solid17.bmp 
>
>
> or rather, in more realistic detail
>
> http://images.cppblog.com/cppblog_com/eryar/Windows-Live-Writer/Topology-and-Geometry-in-OpenCascade-Top_D29F/wps_clip_image-8073_thumb.png?_=1993008393 
>
>
>
>> It works with polyhedra and when they are manifold the
>> STL files doesn't lose anything anyway.
>
> It will not work in general to convert from any mesh based
> representation into OpenCasCade or ACIS, as the model representations
> are very different.
>
> Carsten Arnholm
>
> _______________________________________________
> OpenSCAD mailing list
> [hidden email]
> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>
>
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> Checked by AVG - www.avg.com
> Version: 2016.0.7797 / Virus Database: 4656/13042 - Release Date:
> 09/18/16
>
>


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Re: need a non-STL file format

nophead
Well you are never going to get that out of OpenScad because it converts to polyhedra before doing any operations and a lot of designs generate their own polyhedra programmatically.

On 19 September 2016 at 09:20, Mark Schafer <[hidden email]> wrote:
what is meant (generally) by solid model is that it is made from primitives which are mathematical entities. A collection of polygons does not fall into this def. Here's why they do this:

From a pragmatic point of view its because of this:
- the solids and surfaces that a CAD system uses need to be able to have a number of operators performed on them which are continuous and give 'clean' results. (Yes I'm using all sorts of uselessly vague words. Try to grasp what I'm getting at.)
E.g.  Calculating a tangent so the forces on a tool path can be calculated. A collection of polygons does not have a "smooth" (yes I know) result so interpolation algorithms and other aspects give ill defined results in some circumstances.

So the CAD systems have defined a number of primitives which have well exercised and resolved solutions to all of the manipulations they want to do. OpenCASCADE, Solidworks, ProE, ACIS have what they refer to as solids kernels which resolve all questions for interesctions etc.

Polygons make poor long path trajectories for entities like an Arc because they approximate an Arc, whereas one of the Arc representations will produce a smooth curve at CAM toolpath time, or Forces at simulation time.

so forget words like "real" solids etc etc. Its a pragmatic reduced set of well exercised parametric, math based, solid curve and surface representations that they need.


On 9/19/2016 7:42 PM, [hidden email] wrote:
On 2016-09-19 08:52, nop head wrote:
What is the definition of a "real" solid here?

FreeCAD uses OpenCasCade I think. I am guessing a "real" solid would mean a native CAD geometry/topology model with separate geometry (point,curve,surface and more) and topology (vertex,edge,face,body and more), like you have in OpenCasCade or ACIS. I have used both in the past, but I am more familiar with ACIS. I guess in practical terms a "real" solid could be exported like a STEP (AP214?) or an ACIS .sat file. The difference from OpenSCAD is that these model representations are not polyhedron based. In ACIS a solid would correspond to a BODY or a LUMP.

Does OpenScad even have them to export?

Not a chance, except if you go the indirect route via .csg as previously discussed and export primitives only. Then the receiving end can build the geometry/topology from those. The problem is that you are limited to a few primitives only, and things like hull or minkowski would definitely break it. In ACIS you have

http://p.blog.csdn.net/images/p_blog_csdn_net/feijj2002_/153762/o_solid17.bmp

or rather, in more realistic detail

http://images.cppblog.com/cppblog_com/eryar/Windows-Live-Writer/Topology-and-Geometry-in-OpenCascade-Top_D29F/wps_clip_image-8073_thumb.png?_=1993008393


It works with polyhedra and when they are manifold the
STL files doesn't lose anything anyway.

It will not work in general to convert from any mesh based representation into OpenCasCade or ACIS, as the model representations are very different.

Carsten Arnholm

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