Re: DWG ---> STL Converter ... any other converter from ACAD --> ProEngineer & IDEAS

From: Michael Brindley, C. Rooney (Brock Rooney & Associates Inc.), Paul Brennan (Delcam International PLC), Terry Wohlers (Wohlers Associates)
Date: Wednesday, September 20, 1995

From: Michael Brindley, C. Rooney (Brock Rooney & Associates  Inc.), Paul Brennan (Delcam  International PLC), Terry Wohlers (Wohlers Associates)
To: RP-ML
Date: Wednesday, September 20, 1995
Subject: Re: DWG ---> STL Converter ... any other converter from ACAD --> ProEngineer & IDEAS 
From: zbya@mae.engr.ucf.edu (Buelent Zeyben)
1.) 	Is there any DWG --> STL converter for Autocad R12 ...?
	AutoCAD R13  has one, but I do not know how it works.... 
	Is it a Lisp Program ??


Date: Wed, 20 Sep 95 13:35:13 PDT
From: brindley@ECE.ORST.EDU
> 1.) 	Is there any DWG --> STL converter for Autocad R12 ...?
     In AutoCAD R12, you need the AME (2.1) package.  Then you get
a bonus feature (unsupported) of a Lisp program which creates
STL files.  Or at least tries to create STL files.  In both R12
and R13, then object HAS TO BE A SOLID.  If you created the object
out of surfaces (i.e., did not use AME), then you can't get an
STL file out of it.  Your best bet would probably be to create an
IGES file (using AutoCAD) and then import it into another software
package (ProEngineer, IDEAS, ARIES, HP Solid Designer, etc.).  I
have not tried this, so I don't know how well it works.
     There is also a British CAD package called DelCAM (I think) which
works with surfaces and produces STL files.   This software might
be able to import surface models from other CAD packages and have
a good chance of producing a reasonable STL file.  Again, I 
haven't tried this.  Some one from the company which produces
this software has read this list in the past, so I'm sure we can
get some correction on this.
> 	AutoCAD R13  has one, but I do not know how it works.... 
> 	Is it a Lisp Program ??
     The ACAD R13 documentation does not explicitly state how this is
implemented.  My impression is that it is a function provide by
the ACIS modelling core.  Actually, the technical writing department
at AutoDesk seems to have taken a number of lessons from
MicroSoft - the R13 manuals look much nicer than the R12 ones, but
they have very little substance.  They give you the surface definition
of what commands mean and how to use them, but they refuse to give
you any insight into why the program does certain thing.  So, if
you need to do something which is not covered in the step-by-step
instructions, you have no idea how to approach the problem.
  --> Mike Brindley   brindley@ece.orst.edu     Corvallis, Oregon, USA

Date: Thu, 21 Sep 1995 02:31:05 -0400 (EDT)
From: BROCKROONEY@delphi.com
     Our IGtoSTL will work with IGES files from autocad.  Move your R13 solid
to autosurf and create the IGES file, or use autosurf to create the model.
     We also have STLtoIG which will convert an STL file to IGES (wireframe
or surfaces) so you can read it into any cad system.  BUT to use 
solid modelers like PROE and SDRC, you will want real curved, trimmed
surfaces, not facets, and so you should import Surfaces from the
original CAD model, (using probably IGES) NOT stl files.  
     If you provide your fax number, I can fax you some product info.
C. Brock Rooney, Pres., Brock Rooney & Associates Inc.  (Brockware)
       268 George St.  Birmingham MIchigan 48009  USA
(810) 645-0236   fax/bbs (810) 645-9020  email brockrooney@delphi.com

Date: Thu, 21 Sep 95 10:13:59 PDT
From: pjb@delcam.co.uk
     We were mentioned in  Mike Brindley's mail. Here is some clarification on 
the software products that Delcam have available that help with STL files. 
     The first is our DUCT5 modeller which is used aimed at parts with complex 
surfaces. DUCT will allow you to read surfaces from IGES and add features such
as complex fillets and draft surfaces. DUCT will then produce STL files. 
     The second is Trifix. This was designed to fix Triangles so they become what 
mathematicians call manifold ( closed orientable and connected simplexes). It
can stitch over gaps as well as remove duplicate points and triangles. This is
all achievable to a user defined tolerance. This allows users to stitch 
together bits of triangulation that come from different sources then use rapid
prototyping to create the hybrid object.
     The third is a new product, CopyCAD which can take in digitised data or an 
STL file then produce surfaces. The surface are constructed by "sketching" 
the boundary on to the triangulation, then the surface are automatically 
produced. CopyCAD will output the surfaces in IGES format. 
CopyCAD maintains continuity between surfaces so that the
IGES surfaces can be used in Solid modellers. Also there is a user option
to maintain tangent continuity between the surfaces.
     If you have any questions please contact Clive Martell at the address below
                cpm@delcam.co.uk
as I will be in Taiwan for the next few weeks!
Thanks
	Paul Brennan
- -------------------------------------------------------------------------------
Paul Brennan pjb@delcam.co.uk |Delcam International PLC

Date: 24 Sep 95 15:43:44 EDT
From: Terry Wohlers <73417.1465@compuserve.com>
Buelent Zeyben,
> AutoCAD R13 has one, but I do not know how it works....
     The following explains how to produce an STL file using AutoCAD Release 13.
1. Create a solid model using AutoCAD's built-in solid modeling capabilities. 
2. Issue the STLOUT command, select the solid, and press RETURN.  
If the part lies outside the positive XYZ octant, the command will not work. 
3. Enter Yes to create a binary STL file; No to create an ASCII STL file.
     That's it!  Hope this helps.
Terry Wohlers
Wohlers Associates

Date: 26 Sep 95 12:06:52 EDT
From: Terry Wohlers <73417.1465@compuserve.com>
Alan Craigie,
> There is a bug in the windows version of R13 C3 which prevents this
> function from working. The error message is 'cannot read STL file'. 
> It still works in the DOS version. If you really need this function 
> and work in windows wait for C4 (hopefully this will be fixed).
     Using AutoCAD R13c1 for Windows, I created a plant holder with a wall thickness
of 3.2 mm by revolving a closed polyline.  I then created a binary STL file
from the solid model.  I was able to view the STL data using special viewing
software called SolidView (from Solid Concepts) to verify the integrity of the
STL data.  I discovered that AutoCAD did not properly create the binary STL
file.  In fact, it wasn't even close.  I loaded the same solid model into 13c2
for Windows, and later R13c2 for DOS, and output new binary STL files.  Both
produced good binary STL files, so I concluded that the problem was with R13c1
for Windows.  
     The FACETRES system variable in R13c2 for both Windows and DOS works fine,
based on my tests.  However, it does not work reliably, if at all, in the
Windows version of R13c1.  Note also that R13c1 for Windows produces fewer
facets, compared to the R13c2 versions of AutoCAD, even when FACETRES is set
the same.  I expect that this is another flaw that Autodesk has fixed.
Terry Wohlers
Wohlers Associates


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