Re: Problems with Autodesk products

From: C. Brock Rooney (
Date: Thu Feb 05 1998 - 23:43:09 EET

At 07:04 PM 2/4/98 -0600, VERN CARTER wrote
>I hope someone can help.
>As it turns out, many of our client are using AutoCAD R12 through R14
and/or Mechanical Desktop. We have know for some time that these products do
not produce the best IGES or STL files. This holds true no matter if the
data is surface, solid or otherwise. My question: Is there a way within
these products or through some third party software to produce good STL
files form ACAD NURBS surfaces, ACAD Designer Solids or PMESH 3D models?

If you are using the solid modeler, or AutoSurf surfaces,
we generally have good results with IGES files from the Mechanical Desktop
IGES translator. Output All the surfaces as type 144 trimmed surfaces.
Our IGtoSTL product should work on that. Of course, if the model was built
with Surfaces, the user must be sure the model is complete and tight.

It is generally not desirable to explode surfs/solids into pface meshes, or
3d faces, since the meshing will probably be coarse and non-matching.
To get these models to work with our IGtoSTL, you will need to explode the
meshes into 3dfaces, so the entire model is 3dfaces. These will be output in
iges as 5pt closed polylines (copious data), which IGtoSTL can process as
surfaces. We have other products which can convert DXF files containing
meshes into IGES surfaces, which could then be run thru IGtoSTL.
But again, the best course is to use nurb surfaces or soilds, and output these
to IGES as type 144 Trimmed surfaces.

C. Brock Rooney, Pres., Brock Rooney & Associates Inc. (Brockware)
        915 Westwood Birmingham MIchigan 48009 USA
(248) 645-0236 fax/bbs (248) 645-9020 email

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