RE: machining of STL files

Date: Fri Apr 11 2003 - 11:20:19 EEST

Hi Rohit,

Do you know the Magics Tooling software? This is tool design software that
works on STL files. The process is as follows;

1. Start with an STL file (tolerance 0.01 MM)
2. Automatic splitting, undercut calculation and drafting
3. Customizing of the tool (slides, gating, cooling and ejection system)
4. Selection of housing (ex. DME, Strack, Hasco)
5. Automatic EDM generation

Next we use standard CAM software (NC Strategist)

OK, you may say now, we always do that. In our Tool shop RapidParts Ltd. we
make about 200 to 300 tools every year, and have one tool designer to output
these tools.
This means, that even complex tool designs are completed within 4 hours.
Interesting is also that we have 1 Magics Tooling seat that feeds 3 CAM
seats. So that's productivity.

Tolerances are tool making tolerances: CAM is faceting your IGES or native
CAD file anyway for NC calculation. So designing on facet files will not
affect the final NC tolerance.

In conclusion, RapidParts Ltd. is making a business out of STL tool making
and they go digital all the way; starting from an STL file, they calculate
quotes automatically with Tooling Expert, use Moldflow PA for process
control, use Magics Tooling for tool design and NC Strategist for machining.
Next, we specialize in short-run tools made out of HSC aluminum and EDM
finishing. All tools are internally tested and limited batch series are
provided as part of the service. It's our goal to deliver tools and test
series within 20 working days.

So what are the advantages of STL tooling:

1. STL means effective file exchange.
2. STL allows design automation. A complex part geometry is simplified when
it's triangulated. Splitting for example of simple parts as complex designs
have the same mathematical complexity (only calculation may take longer).
3. The same CAM strategies can be used on a worked STL as on an IGES file.
4. The overall quality remains while productivity benefits.


Tom De Bruyne


-----Original Message-----
From: Rohit Kumar []
Sent: Wednesday, April 09, 2003 9:31 PM
Subject: machining of STL files


I had a question on machining of STL files.

Since STL files are faceted, if mold is machined, what's the
guarantee that the core and cavity would seal properly
(assuming the parting line is not perfectly straight and has
sort of a contour to it)?

My understanding is that if the resolution of the triangles
is within that of the milling process, then there is no
problem. However, if it's not, what happens then? For molds
made via SLA, the mold material is soft. So applying
pressure, would sort of deform the material such that at the
parting plane, the core and cavity make a seal. But say if
the mold is made out of tool steel, what happens then? BTW,
is mold ever made out of tool steel via STL files?

Any inputs will be appreciated.
Best regards,

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