Learning Surfaces

I noticed that there are only two examples of Surface Geometry in the
Solidworks help files. "Surfaces", and "3-D Sketching with planes".
Is there somewhere I can go for the real basic principles? Maybe
explaining the many individual features that make up the whole of
Surfaces. The Community College that I attend doesn't offer Solidworks
Level II, at all. Level II involves Surfaces, Photoworks, Animation,
Cosmoworks, Routing, etc.
I did see some real nice Powerpoint tutorials on the net from Di Monti
web site, and also from a site by Lombard, but I believe they must be
designed for someone that posesses basic knowledge, at the very least,
and knowing nothing at all about surfaces, I was totally lost going
through them. The people that made the tutorials were obviously
brilliant people, but taught way beyond the level that I am at, at
this point at least. I am hoping to find an instructor with the
ability to explain the mechanics of Surface Geometry at a level that a
complete novice will absorb. I am thinking that there must be some
real basic info somewhere, like there is explaining the fundamentals
of Solid Geometry.
I do have two books by David Murray, but for some reason Surfaces is
not covered at all. Can I be placing too much attention on the value
of knowing Surface Geometry? Is there something that I am not knowing
here? Why is there not the same amount of literature available for
both phases of Solidworks I wonder? Or maybe I am simply deficient
in my ability to locate it?
Carl

 

interestingly, this came up just last week on this newsgroup. Here's
a copy of my response:

The rudiments are simple once you really look at what solid and
surface features do

To begin with, Solid features ARE surface features, except:
A) Solid features ALWAYS make a completely enclosed volume (which you
can see in the preview for a cut, or if you deselect 'merge result'
when making a boss then go to the solid bodies folder and hide the
other bodies), while surface features are not limited by that
constraint
B) Solid features know which side of the faces it creates makes
'stuff', and which side makes 'void'. A surface sitting in space on
its own, even if it does describe a completely enclosed volume, has
no
definition as to which side is 'stuff' and which side is 'void'. Is
that surface a cylinder, or is it a drilled hole? It doesn't know
until you tell it using 'thicken' or 'cut with surface'


I find it impossible to get caught in this rut about solid features
vs
surface features, and simply put it out of my mind years ago. They
are different, yes, but only in execution. At the end of the day
they
both make the same thing - faces.


When it comes to modeling, the only thing that matters is faces.
Repeat that to yourself - the only thing that matters is faces. When
your product is being made on the shop floor, or when it is on a
shelf/
delivered to a customer, the only thing that ever mattered was the
faces of the object. That's what we do with our CAD - make faces.
And
our deliverables don't care how those faces were made.


Solid features make faces, but they always (well, almost always -
there are spheres) have to make a few extra faces in order to follow
the rule of delivering a completely enclosed volume. Which can be
hard to visualize in the case of a cut... that's why I say look at
the
preview and you can see how a volume is made when you execute a cut,
before it is subtracted behind the scenes from the
'workpiece' (otherwise known as that existing chunk of 'stuff' on
your screen).


Surface features don't have that limit - you can make one or several
faces at a time, then trim or knit those faces together to make the
final model.


If you have the time, try to make a simple model one face at a time,
using surfaces, to see how it works. Its horribly inefficient on
simple cases (making a cube one face at a time requires 8 features,
for instance - 6 planar surfaces, a knit, then a thicken enclosed
volume), but you will learn how it works. That is what every 'solid'
feature you have ever made does behind the scenes - solids are
'macros' for the tedious work of making things one face at a time out
of surfaces.


But there are times when making model geometry one face at a time
DOES
make sense, and catapults you past problems that you run into when
having to deal with that 'fully enclosed volume' restriction of solid
features. There are samples on the Dimontegroup web site that talk
about some of those problems, but apparently not clearly enough.
Sorry
'bout that - I tried. As soon as I figure out how to rewrite the
damn
site there will be one more tutorial from this years SWx World that
has (I hope) some of the clearest samples I have ever done talking
about 'making faces'.


It's good to have surfacing knowledge in your magic bag of trix
because there are times when doing things 'one face at a time' (or
more probably, several faces at a time, just not as a completely
enclosed volumes) with surfaces actually is wayyyy more efficient.
Super mega wayyy more efficient.


And a lot of times, its the only way to get to the finish line - I
have been using SWx for nine years, and I would gladly bow down,
grovel, and wash the feet of the person who really can deliver on the
statement that 'anything that can be done can be done in solids'.


A 'hybrid' approach (that is stupid slang for mixing surfaces and
solids) is, in my experience and the experience of many others, the
most appropriate way to go on certain projects. But again, bringing
back to earlier in the post, I don't even think of its as a 'hybrid'
approach because both surfaces and solids just make faces - if you
pick features based on their ability to make the faces you need the
most efficient way, there is no switching from one modeling
environment to another. SWx is just one big 'making faces' tool. Cuts
and bosses both make faces in different ways and we don't think of
THAT as a 'hybrid' thing - why should we apply an arbitrary division
to solids and surfaces?.


I hope this helped - I do not envy you for having to learn this stuff
from the ground up. I am learning new software right now and am
newly
reminded how horrible it is to get straight, useful answers on
fundamental issues that most people using the software have already
come to terms with. Keep asking the questions, Amy (and you, Carle),
until you get an
answer framed in a way that makes the breakthrough for you.


Ed

 

I don't use surface modelling so I'm no expert, but in I-DEAS there is a
function to set the "material side" of a surface, so that it does know how
to respond to further modelling features.
Maybe if that's not in SWX then it could be an enhancement request.

John H

 

Rather than starting with Curvy Stuff 101 on the DiMonte Group site, try the
SWW 2005 presentation, "Surfacing for Blockheads". It is particularly aimed
at people who don't normally think about using surfaces.

Jerry Steiger
Tripod Data Systems
"take the garbage out, dear"