Re: Complete RP certification

From: Markus Hitter (
Date: Wed Feb 26 2003 - 12:46:01 EET

Am Dienstag, 25.02.03 um 17:20 Uhr schrieb Blasch, Larry:

> I am on record saying that we no longer need to use STL data when
> building
> parts created with a solid modeling program. It is at best a crude
> approximation of the "surface" of the 3D model. I would prefer to build
> parts from the CAD file.
> Using STL for part data transfers is like sending MSWord files in fax
> data
> format.


well said.

> Sure, any fax machine can print it...

This is the exact reason why STL files will stay there for a long time.

> The data format is not representative of the original

It doesn't represent all the model but all you need to build your part.

> Before I get flamed, Yes, I know that not everyone works with competent
> solid modeling software. If your CAD program sucks get a better one and
> don't complain to me.

Depends on what you require to qualify a CAD package as "competent".
There are at least 20 major packages on the market and all of the ones
I've seen over the last 5 years can export STL, just because it's so
easy to implement it. If you require ACIS or STEP or whatever else, you
probably drop out 10 of them.

In my area, I never had a problem to tell customers how to generate STL
with a sufficient resolution. A one time overhead, but saves lots of
time later. Or does your "competent" CAD package generate laser paths
for you RP machine directly?

One additional note: Most path generating tools tesselate surfaces
internally, anyway. So you always go through some sort of "STL".

Of course, some real standard with freely available programming code
libraries for exact surfaces would be most welcome. But once you've
tried to implement an IGES Viewer or some similar software, you'll
quickly learn this isn't a one week task, at least at this point in
time. In opposite to an STL Viewer.

Yet another $0.02 :-)

Have fun,
Markus Hitter

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Dipl. Ing. Markus Hitter

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