BIG SNIP
there
are no CAD file standards as far as we have been able to discover even
in DXF
file format. Everybody seems to use a different CAD program.
Paul Lamar
IGES is pretty close to a std exchange format (that is what we spent
10+
yrs trying
for, at least). The only problem is that AutoCAD just moved their
translator into
a separate extra cost "enhancement" rather than have it as a std part of
the
package.
Most CAD packages will read and write some level of IGES file. IGES is
just a
std, so the translators (in and out) can vary from great to crap. I
just
brought a
solid model into I-DEAS yesterday from ProE with IGES and the resulting
part was
good enough that I could modify it in my package. This is amazing
progress
in the
last few years. The IGES std has been OK for a long time, but the
translators have
often been poorly executed - just good enough to claim "IGES capable" in
the
ads.
Bill Freeman
Long EZ builder & pilot
BSME, MSME
Monty Roberts wrote:
You guys using Auto CAD need to get with the new millennium. I used to use
Auto CAD, since then I have moved on to much cheaper, much better design
packages. Auto CAD is a victim of Legacy support problems. The only folks
that use auto cad in the design world any more are the Architectural ME guys
and those that simply refuse to learn new technology. Auto Cad is restricted
in how much innovation that they can incorporate into their software because
they have to support all of the old archaic ways of doing things. A much
better solution for guys on a budget is to use Rhino for surface modeling,
and forget about auto cad. Or if you have auto cad, use it in conjunction
with Rhino for drawings maybe. (I bet you a large sum of money you don't use
AutoCAD much after you find out how bad it really is.)
http://www.rhino3d.com/
The full blown package is only $900 bucks and the file translator alone is
worth that. With this you can talk to almost any package out there. You can
make stereo lithography files, parasolid files, pro e files, solid edge,
unigraphics, even auto cad, and you can read 3D digitized data. The only
drawback is that it is really just a surface modeling package. Forget about
doing real solid modeling here. However, even in $20K plus packages, intense
free form parts (airplanes) become surface models anyway, (this is why
Paul's friend had problems modeling the intake runners in Pro and Solid
Works). You just have to work a little harder on the simple solids in Rhino.
Rhino is essentially Poor mans Alias, one of those mega $$$$ packages used
for industrial design. I have used Alias, Unigraphics and Solid Edge. I can
say that Rhino is easy, fast, and works great. For those of you still
designing in 2D, 3D is INCREDIBLE. I don't even want to think about doing
things the old way anymore (it makes my head hurt to think of all of those
view projections!!!) Rhino is not parametric, which in my opinion is no big
loss for what most of us are doing.
IGES is probably the closest thing to a universal cad file but it SUCKS!!!!!
It would be much better to use something like parasolid. Of course Auto slug
can't read parasolid without some type of expensive translator. (I really
cringe when a vendor tells me they use Auto cad, because I know we are in
for a bunch of headaches) If we were to use IGES as a standard, everybody
better be ready to do a lot of part clean up and such. And how you make the
file is very important in making it readable.
For CAM files the best thing would probably be to post a jpeg picture of the
part along with a FANUC compatible G code file. Most machine tools can read
this, and the programmer can add the appropriate M codes for the tool being
used. Trying to standardize on a CAD/CAM program is pointless.
As far as drawings go, they are obsolete. The data base rules! All we need
is a 3D data base and a deminimus 3 view drawing and a spec. sheet.
What you are suggesting is that we set up engineering design standards for
this group. Having done this in the real world, I can say that it is no easy
task to get a good system up and running. BUT I think that you may be on to
something!!! If we did do something like this it would definitely bring
economies of scale to work for us and allow future users to benefit from the
vast experience of all the members. It would be nice if we could download
the parts/designs that have been done in the past and incorporate them into
our projects thus saving a tremendous amount of time!!! It would spread the
development cost across all the members. This is something that has just
become a possibility with the technology available in the last five
years!!!! It may actually make the alternative engine idea feasible for most
people. We could bypass the middle man (Lyconental, dealers, etc) and use
rapid manufacturing to make parts available to people as they need them.
There are no shipping costs. You download the file, and have it made at your
local machine shop. You can customize the part if you wish. The era of mass
customization with economies of scale is upon us!!! Distributed
manufacturing and collaborative design.
This is a kind of collective design approach which is very cutting edge.
Many design people are talking about a similar kind of thing for actual
products. (I actually do this for a living to some degree) The main
difference being that they are professionals collaborating from different
parts of the world on virtual designs for pay. Here the pay would be a
reasonably priced engine which would work. There are questions of Liability
however. I for one do not wish to subject myself and my business to
liability. What if someone crashes and sues the member who designed a part.
(NOT GOOD!!!) If we were to form a type of club or association, where each
person had to join in order to get access to the files, I think that it
eliminates a lot of this. (you can't sue yourself) If there are any Lawyers
out there please comment on this aspect. If it is a world wide consortium,
where would the trial be? The Hague, the first virtual court? All new stuff!
This could be a new way of doing things guys. Capital allocation through
collaborative research. This may be the most democratic and efficient
allocation of capital and resources yet!! If people want a technology that a
company will not tackle because of lack of profit or too much liability,
they form an association and collaborate because of a shared interest!! Talk
about voting with your checkbook!!! If there is too small a market and too
much liability, this may be the only way things get done. This is how our
space program got started with Von Braun in the early days, he got together
with his rocket buddies and they collaborated to build rockets (before the
war of course). Imagine if all the people in the world interested in space
travel could get together and do the same thing today!! Working together
just for the shared interest, no governments, no politics. (NASA - never
access space again ;-) Of course I'm not so naive to think that the
government would not intrude into such an enterprise, you would be stepping
all over their turf. Can't have the Cows getting out of the pen, how would
they milk us??
For a system like this to work it must be a kind of automated template.
Devoting a lot of time is out of the question, so the thing will have to run
itself. After the initial setup, I don't see why this can't be done. I think
that there is some free ware out there that does this sort of thing,
something similar to a Yahoo group, with files etc. We would just have to
come up with internal part file guidlines. Some of you web development gurus
comment on this a little bit, Greg?
EXCITING CONCEPT!!!!
Monty
The AirCraft Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/ http://www.linux.org