Re: .STL from IDEAS

From: Andrzejewski, Jan (
Date: Thu May 11 2000 - 12:52:42 EEST reply to Robert S. Gansen request for procedure
and ideal settings for creating an .stl from IDEAS covered most of the
procedure and I do not want to repeat it and others have chipped in with
additional information.

What I would like to add are some helpful hints and correct some anomalies.

First of all shade the part then you will have no problem visualising the
mesh when you click on the 'show facets' button.

Dynamic rotation of the part will give a better indication of the facet mesh
on the surface geometry.

Look out for areas that do not have complete mesh edges superimposed on the
shaded surface.

If the part is not a solid but is a surface model (eg imported IGES file)
then try to stitch the surfaces together, if surfaces overlap these will be
highlighted and you need to manually trim them. (could be a long job)

You can also use the 'show free edges' option to understand where the holes
in the surface model are.

If you can not completely turn the surfaces into a solid model then when you
shade the model some of the surfaces will not display the correct colour.
(this is where you will get inverted facets)

You do not need to delete any curves, lines or points just select the filter
option for surfaces only.

With SDRC Ideas Master Series version 2.1
Changing the isoline density does not do anything to increase the facet
Select a sphere from the standard parts directory (Radius 35mm)
Choose absolute facet deviation of 0.02mm
With the isoline density of 0 the number of facets will be 12088
changing the isoline density to 1, 2 and 3 will give a surface visualisation
of a surface change but the number of facets will remain the same 12088.
If this has changed with the latest version will some one try this simple
test and confirm it with me and the list.

Sometimes you may have a model that is bigger than the SLA-500 option. In
this case edit the file SLA-500.dat and put the size you want. (I have
SLA-BIG file that is 1m cube just in case 3D Systems go mad and build one
that big). If anyone wants more info on how to edit this file contact me

Lastly although I like using Ideas for ease of its use, the STL output is
not of the standard that I like to use with our SLA350 so I find that I will
export an IGES file, selecting flavour 9 (GM GDS) and read this into STRIM
100 for a better mesh resolution.

I have also had better meshing densities using Rhino although it does not
have any topology checking routines so some of the IGES surfaces from the
solid model creates inverted facets.

Jan Andrzejewski
RP Project Manager
Technology Centre
Nottingham Road
Melton Mowbray
LE13 0PB
Tel +44 (0) 1664 501501 Fax +44 (0) 1664 501556

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