Cad File Formats (was programing a DRO)

Matt, The concept of .dxf as the universal format must have the folks
at autoDesk laughing their heads off as they have changed it with
ever release... and if you add in about 50 or 100 other flavors of
.dxf floating around... well it's a bit of a mess really.

I have had the best luck in getting files in and out of the ashlar
velum solids99 program I use to be the .Sat format but that is for
3d and only for software that uses ACIS.

Sat is for exchange of 3d files between software that uses the ACIS
shell from Spatial tech (over 200 applications and 1.5 million users
at last count) to date I have used .sat files from Autocad , Ironcad
, FromZ , and Turbo Cad with no problems... if any here use an ACIS
enabled Cad/Cam program I would enjoy sending them a few files to
test this going the other way

That is not the case with .dxf or .dwg or .igs... and if I ever do
make the move to real CAM this is the current list of acis based Cam
software. I should be able find something in this list..
Http://www.spatial.com/action/applications.htm

I did not buy my copy of Velum Solids99 I got it as a bonus in
addition to some contract development work I did for Ashlar... but
even at $3,000 a seat I think It's good value ...

(If any windows users want to look at the demo version on the Ashlar
site Http:/www.ashlar.com (call them to ask for a demo CD rom)
they should know that until the Mac version is changed from QD3d to
OpenGL the Windows and NT versions of it are actually slightly
faster; on a SGI 450 under NT vrs my B&W 350 the SGI will do final
ray traced renders about 10% to 15% quicker right now) so until the
fall, the fastest implementation of VS99 is on a high end NT
workstation (on operations that don't use Open GL like rendering to a
file the B&W Mac 350 is about 5% faster than the SGI 450 right now)

... in a few weeks i will have some examples of Model engineer sorts
of things I have done with it up on my web page... I am doing a
Virtual version of the Stuart Steam hammer before I start cutting
metal... I model the casting as a solid than 'machine it on the
screen" then select it and have VS99 create a 4 view drawing sheet
with sections a "B" sized 11x17 sheet for each part... I have it
about 1/2 done and when finished I will use it to make an animated
version that I will post on my page...

another format that might be useful to the list as a conversion base
is the .stl format used for stereo lithography... it's main problem
is it's very very wordy... Here is a .stl file for a 1 inch plain
cube it is about 2 k long... if I round over the the the 4 edges of
the top face with .050 radius the file grows to 137k! (be glad to
send it to any one who is interested... ) complex .stl files are Huge
but they are simple... and might be amenable to simple parsing into
Cam file formats... are there any Solid litho experts on the list
yet?
solid ascii
facet normal 0.000000 0.000000 1.000000
outer loop
vertex 1.000000 1.000000 1.000000
vertex 0.000000 1.000000 1.000000
vertex 1.000000 0.000000 1.000000
endloop
endfacet
facet normal 0.000000 0.000000 1.000000
outer loop
vertex 1.000000 0.000000 1.000000
vertex 0.000000 1.000000 1.000000
vertex 0.000000 0.000000 1.000000
endloop
endfacet
facet normal 0.000000 0.000000 -1.000000
outer loop
vertex 1.000000 0.000000 0.000000
vertex 0.000000 0.000000 0.000000
vertex 1.000000 1.000000 0.000000
endloop
endfacet
facet normal 0.000000 0.000000 -1.000000
outer loop
vertex 1.000000 1.000000 0.000000
vertex 0.000000 0.000000 0.000000
vertex 0.000000 1.000000 0.000000
endloop
endfacet
facet normal 0.000000 -1.000000 0.000000
outer loop
vertex 0.000000 0.000000 1.000000
vertex 0.000000 0.000000 0.000000
vertex 1.000000 0.000000 1.000000
endloop
endfacet
facet normal 0.000000 -1.000000 0.000000
outer loop
vertex 1.000000 0.000000 1.000000
vertex 0.000000 0.000000 0.000000
vertex 1.000000 0.000000 0.000000
endloop
endfacet
facet normal -1.000000 0.000000 0.000000
outer loop
vertex 0.000000 1.000000 1.000000
vertex 0.000000 1.000000 0.000000
vertex 0.000000 0.000000 1.000000
endloop
endfacet
facet normal -1.000000 0.000000 0.000000
outer loop
vertex 0.000000 0.000000 1.000000
vertex 0.000000 1.000000 0.000000
vertex 0.000000 0.000000 0.000000
endloop
endfacet
facet normal 0.000000 1.000000 0.000000
outer loop
vertex 1.000000 1.000000 1.000000
vertex 1.000000 1.000000 0.000000
vertex 0.000000 1.000000 1.000000
endloop
endfacet
facet normal 0.000000 1.000000 0.000000
outer loop
vertex 0.000000 1.000000 1.000000
vertex 1.000000 1.000000 0.000000
vertex 0.000000 1.000000 0.000000
endloop
endfacet
facet normal 1.000000 0.000000 0.000000
outer loop
vertex 1.000000 0.000000 1.000000
vertex 1.000000 0.000000 0.000000
vertex 1.000000 1.000000 1.000000
endloop
endfacet
facet normal 1.000000 0.000000 0.000000
outer loop
vertex 1.000000 1.000000 1.000000
vertex 1.000000 0.000000 0.000000
vertex 1.000000 1.000000 0.000000
endloop
endfacet
end solid

>From: "Matt Shaver" <mshaver@...>
>
> > From: <blinda@...>
> >
> > I wrote a program
> > to read the dxf file and produce the m and g codes for my machine. The
> > program is simple minded but works pretty well for my purposes. I had
> > planned to make several improvements before offering it for use by others
> > but I'm not not optimistic I'll do that now. If you or anyone else on
> > the list are interested I can make it available.
>
>I'd be interested in seeing this, manly as a tutorial on the innards of .DXF
>file structure! I'm wondering if .DXF is consistent between Cad programs, or
>if their is a core set of entities and functions that everyone supports plus
>a bunch of platform specific garbage that would need filtering out. It looks
>like .DXF is going to stay THE data interchange standard for CAD data in the
>real world, although I had high hopes for VRML taking over this role at one
>time. IGES was also a promising standard before it went "Hollywood" as STEP.
>See this site for the last public definition of this once useful standard:
>
>http://www.iges5x.org/

Randolph Lee boss@...
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Windshadow Engineering Nantucket Island, MA USA
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