I have used various types of Rapid Prototyping processes over the past few
years with a great deal of success. We currently have on order a Stratasys
FDM 1650 system. Yes, the STL file "describes" the CAD model as a series of
facets on all surfaces and is the standard input used by all RP systems.
This should be simply viewed as only a way to transfer the CAD part data to
the Service Bureau. They will do the rest. Following is the method that I
use to create STL files:
Createing an STL file:
A. Check the parts validity by calculating a volume. It should be able
to calculate the volume with no open surfaces to be a good part. Also
delete unnecessary lines and points.
B. Enter the "Export", "Rapid Prototyping" module to create the STL
file. With one part showing on the screen (not manditory), select the
icon that is the file folder and a form will appear:
In the first box, use the file folder to get the RP system list.
In the second box, use the file folder to get the positioning list.
In the above two selections, you must keep in mind that you are
creating a "universal" file that can be used with all RP system. I
choose the "SLA-500" and "Origin" so that I will not get the warning
that the part will not fit in the RP workspace. I really doesn't
matter which setting that you select because the RP Service Bureau
will manipulate your STL file to the proper orientation for their
In the third box, enter the filename to be created for this file.
For "Facet diviation", input ".002".
This is a setting that determines the number of facets that are used
to describe the CAD part. Sometimes refered to as a tolerance. This
setting was suggested by a Service Bureau and has worked well for me.
I sometimes use .0015 although these settings are too small for some
applications and may be unnecessary. The smaller the setting, the more
facets, the larger the file size, the more difficult to send out.
Select "Show Facets". (pretty messy, huh?) This is only for your
If an error or warning appears that the part will not fit in the
machine space, ignore it.
C. The .STL file has now been created and will reside in your ideas
D. Place the file in the Directory that you want it to reside in. Unlike
IGES files, an STL file is not linked to your I-DEAS part and may be
manipulated freely within your OS.
E. Compress the STL file and send to the Service Bureau. I usually use
FTP as it is easy, quick, accurate and cheap. E-mail will also work, but
larger files will choke-up and may take days to reach the receiver.
Hope this helps.
For more information about the rp-ml, see http://ltk.hut.fi/rp-ml/
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