CAD Tool For Design Tiny Aircraft

On Sep 30, 9:40 pm, jon_banquer wrote:
Suggest you find your way ASAP towww.kubotekusa.comand view their
video on direct dimension editing to see what can be done without
parametrics.

Ok, I just watched the video, and I barely understand anything, as I
am an ignoramus when it comes to CAD. However, it seems that the "dumb
geometry", as the presenter calls it, allows "dumb dimension-based
editing", but after you are done fiddling with "witness lines, etc.",
you have your model, and nothing else.

Parametric modeling, OTOH, as I understand it, allows the programmer
to define constraints, and let those constraints rest in a sack that
is carried around with the model. If that is the case, I *absolutely
love* this feature! The power of this approach should be apparent, I
think, no?

Now I think I see what TOP meant in his response to your post, about
spaghetti code. I think the preference for the models depends on the
approach to designing systems. Some people think in terms of
relatives. Some think in terms of absolutes. I think in terms of
absolutes. I'd rather walk around in woods for 2 or 3 days working out
the kinks of a system in my head before I commit to anything, even if
I think I already have 40% of the answer. Only when I am sure that
the remaining irregularities are so minor that they will not impede
the march toward finalization of the design will I commit. Then I
employ the tool bear down upon my preconception of the system to see
that it is correct and to optimize it. I guess this is why I prefer
parametric. It seems like it is the right tool for the tightening
process during optimization.

Incidentally, that is the whole reason I've decided to fiddle with CAD
to make minitature plane, to see how much cost reduction can be
achieved by rethinking the system as a whole and not simply trying to
get better prices on conventional components.

-Le Chaud Lapin-

Ok, I just watched the video, and I barely understand anything, as I
am an ignoramus when it comes to CAD. However, it seems that the "dumb
geometry", as the presenter calls it, allows "dumb dimension-based
editing", but after you are done fiddling with "witness lines, etc.",
you have your model, and nothing else.

It's very important to understand that parametric data does not get
exchanged
between different cad systems. What you get is a "dumb solid" when you
open
your model done in Solidworks in another system like SolidEdge. All
the design
intent / parametrics you established in SolidWorks will be gone.

Now I think I see what TOP meant in his response to your post, about
spaghetti code.

His example is one sided and doesn't give you the downside of
parametric
modeling.

http://management.cadalyst.com/cadma...ID=1&sk=&date=

"KeyCreator is a nonparametric application, but that isn't necessarily
bad. It gives users the freedom to do all kinds of things to a model
that they'd never think of doing in a history-based system."

I use SolidWorks everyday. I don't use KeyCreator. I'm not foolish
enough to think that a parametric / history based approach to modeling
is the only approach or always the right approach and unlike most
others in the SolidWorks newsgroup I'm not a product loyalist. Dana
Hague had some very valid points in his post to you.


Jon Banquer
San Diego, CA
http://worldcadaccess.typepad.com/bl...mment-76366100

Your walk in the woods method is something that I run into every day.
Unless you have a very special mind, spatial relationships are very
difficult to imagine and solve mentally. You can get the topology in
your head, but when it comes to parts bumping into each other in 3D,
most heads can't get around it. 3D CAD brings you down to reality in a
way that even 2D CAD cannot do because in many ways 2D CAD is still a
mental excercise (Thank you Gaspard Monges). Frequently you will
encounter people with ideas that don't stand the test of 3D. This
isn't just an associate with a quick scribble on an envelope, but even
many 2D drawings are simply cartoons. What 3D CAD is, is a way to
simulate reality realistically (well up to a point). There is a
continuum:

1. 2D CAD (catches and idea, still much is required in the head)
2. 3D CAD (captures the 3D constraints, will it fit, etc.)
3. Kinematics software (will it move the way I intend, what are the
rigid body forces)
4. FEA/CFD (How will it deform, How will air flow over it?)

The first is probably the quickest route to getting a specific idea on
paper. The next one is more flexible and more time consuming. The
third requires the work of the second plus additional work and the
last also requires the second and perhaps output from the third to
give good answers.

Since SW starts with 2D sketches for the most part it captures much of
1 and pretty much all of 2.

TOP