Re: "Solidifying" STL - How to get the shell only?

From: Mark Bliek (
Date: Thu Jun 12 1997 - 02:37:58 EEST


It should be possible to quickly correct an STL-model consisting out of
more shells merged into 1 STL-file, with Magics RP. What you should do is
output the different shells again into separate STL-files with the 'Convert
shells to part option' in the Tools menu. The separated STL-files can then
be manipulated individually. After closing each STL-file use the Boolean
operations 'unite' to make one STL file again. (When closing large defects,
try also the fill hole option, which is useful when you have missing
surfaces, just click on the edge where the surface should be, and the
missing area will be filled in, following the edge).

Mark Bliek
Materialise USA
(313) 662 5057
(313) 662 7891
> From: Robert Roy <>
> To: RP Mailing List <>
> Subject: "Solidifying" STL - How to get the shell only?
> Date: Wednesday, June 04, 1997 7:04 PM
> Hi all,
> (I have already sent this message once before (to but
> haven't seen it show up in the list, so here goes again)
> We are attempting to slice an STL file of an object produced using a
> visual-rendering-oriented modelling system (a figurine from Lightwave in
> this example, but it's the general solution I'm after).
> The output form this class of software is normally intended only for
> visual rendering and is not "solid-oriented". Features added to the
> surface of the figurine extend through the surface into the interior,
> and the internal "walls" of the blocks used to define the features
> survive in the interior. Put another way, when constructing the model
> the boolean union of any two "solid" or enclosed areas has resulted in
> the combination of both meshes, NOT the "outsides" only of the two
> meshes.
> To make life even more difficult, there are of course overlaps in the
> surfaces and large gaps between edges. This does not present a problem
> when rendering for TV or print but makes RP prep a nightmare.
> We have Magics RP here that seems to do a good job of repairing small
> gaps and minor errors but it's far too time consuming for major repair
> work. We need a simple method of removing everything except the outer
> shell, perhaps with adjustable tolerance for gap width.
> Any ideas? We have played a little with the trial version of DeskProto,
> an STL to NC machining package, but that doesn't seem to have a way of
> outputing anything other than tool paths - no good for our Sanders
> ModelMaker! We ultimately need a repaired STL output, although we could
> go via Wavefront (.OBJ), DXF (rather not!) or even SolidWorks (.PRT,
> .SAT etc).
> Thanks for your help.
> Rob
> --
> =====================================================================
> | Rob Roy | Protoforté Pty Ltd - RP Bureau |
> | Castle Hill, NSW, Australia | Sanders ModelMaker VAR for Aus/NZ |
> |P+61-2-98942995 F+61-2-98942868 | Go to |
> =====================================================================
> | Protoforté - "The Precision Edge in Rapid Prototyping" |
> =====================================================================

This archive was generated by hypermail 2.1.2 : Tue Jun 05 2001 - 22:39:43 EEST