SolidWorks 2005 Surface Tangency

Couple of comments:

That much is OK.

This much is BS. A cutter can gouge if the surfaces are C0, C1, C2, C3 or
more... if the cutter nose radius is larger than the local surface
radius - and - your CAM program doesn't have gouge checking. Otherwise, no
problem. Also, depends whether it's an inside or outside condition.

Again, BS.

Bees knees for who? In what application? Your definition doesn't help.

You also posted this:

"Generally, there are three kinds of boundary
conditions in a surface model. C0 refers to surfaces
that are just touching but could potentially have a
shape corner or crease; possible manufacturing
problems can result. C1 refers to a tangent (smooth)
condition, and C2 to a consistent continuous tangent
curvature. With C2, the boundary is imperceptible to
the eye-you can't see were one surface begins and
where on ends."

Which gives a little bit better clue to C2, as it's listed in terms of eye
perception. That's what it's all about - visuals.

Note that there is often discussion of C3 (or G3) or even higher curvature
continuous joints. What are they? Well C2 or G2 are have continuous
curvature at the joint, but the *rate of change of that curvature* is
different on either side of the joint. People (especially in the automotive
body surfacing field) *claim* that this can still be seen, so they want
C3/G3, which the rate of change of the curvature at the joint is also equal.
Very few programs can do this, probably stuff like ICEM surf... Maybe
Alias. Catia?

Note also that these conditions can occur either at a joint between two
discreet surfaces, or actually within a single surface - that is to say a
single surface can be internally C0, C1, C2, C3, etc. Although C0 (kinked)
single surfaces are allowed in NURBS and BREP geometry, they are not often
used - most programs like to split them into separate surfaces at the
kink(s). I can, however, make a single surface cube in Rhino (that's right
, only one surface), send it out via IGES to Surfcam, and mill it with a
single cut operation. If gouge checking is turned on, it will mill what it
can see and leave the rest alone.

Lastly, the usefulness of C2 or higher joint conditions depends on the
application. Circular fillets are G1. For mechanical parts, this is fine -
having C2 fillets would be ridiculous. But for ID/appearance applications,
or perhaps things where air or fluid drag come into play, it can be
important.

Note, no quotes from anyone here... Except your posts.

--Mitch

 

It must be the American way, I suppose, my tribe your tribe attitude :-S
We don't have that here in my company, everyone is called by their first
name, no Mr sir or boss.

Strange that you never got to try other demo's, was this your choice or was
you forced into using one package?

Don't get me wrong, I love Solidworks, (when it works), I have even just
sighed up for a 3 year deal with my VAR, But I am always looking for a
better way of doing things.
I found that Solidworks was better, (for me), than Autocad for doing lots of
things what I want.
Autocad still has it's place in my company and we still use it.
The main problem I have with solidworks, is the slooowness of it, (could be
just me!).
In a big company, this is easily to cover, but in a small company it can
break you.

I would suggest that everyone should try other packages, you never know, you
might find a better one.
Otherwise India's workforce might start taking more work from you, as they
have also started to take from us.

Remember, Time is money and attitude is pants!

 

Thanks Mitch, I don't use cam, so had no idea what this post was about, lol

Knowledge is a wonderful thing, gained by people willing to learn, shunned
by morons!

 

Knowledge is a wonderful thing, gained by people willing to learn, shunned
by morons!

 

http://news2.mcneel.com/scripts/dnewsweb.exe?cmd=article&group=rhino&item=1
88606&utag=

might help if still grappling with the definitions.

 

Whats up with this American way stuff?
I run my company. I make money, we build molds and my tribe calls me by
name not Mr or sir.

Nothing was forced on me.
I used Solid Edge for 2 years before SW. At the one company they had SW
and I liked it so I migrated it to my present place and I've enjoyed much
success with it.

Well, I dont know about yer situation. Maybe you just aint using it or
have it setup correctly. IMO Autocrap is just that, crap. They have never
catered to us moldmakers till recently and even that I find a joke.
I feed 8 guys mold designs every month and they are busy. A normal mold
with slides takes me about a week to design. Hydraulics, 3 plates, hot
runners etc maybe a week and a half. I dont see how it is slow. There are
some quirks with the latest release that I dont like, but its not a major
issue to me.

And I would suggest that people quit wasting their time demoing every
piece of software around and not producing anything. I would suggest that
they actually use a piece of software to like actually make something for
a change.

Its a dirty job and I reckon somebody has to do it, but I aint got time
for it.

Bing

 

Again, this clearly shows that you are a total idiot, have no clues
at all and have NEVER used any of this stuff for CAD *OR* CAM.

CLUE (The day's free one): A planar fillet tangent to two lines
is C1. Such are machined by even novice CNC programmers
(You are not even one of those, quite clearly) and designed
quite easily (you are no designer either).

Anyone still think that this idiot has clue #1?

 

You just copied/stole that and have no idea what it means or if it's
even remotely correct.
Idiot.

 

"Boundary conditions"? LMAO !!!

And only THREE?

Well, from a *styling* point of view, that's probably important.
But it's not what it means.

Need there be "joints"?

CN/GN ...... what's the maximum exponent of the polynomial supported
by the system for surfaces?
IIRC Some have up to degree 17 or so. That would support C16/G16
or so surfaces, right?

BTW, Ask the idiot about his surface directions <VBG>. He's hugely
confused & probably thinking in 2D planar terms. Or the person he
copied the stuff from (it's not his as he has no clues) was.

LOL ... Poor jb's just so very clueless (but more than happy to lie
in any case, as always).

 

I see you have met jb <G>.

 

http://news2.mcneel.com/scripts/dne...since=-9999&search_before=0&search_sort=score


http://news2.mcneel.com/scripts/dne...arch_before=0&search_match=&search_sort=score

Isn't jb banned there still?

 

IIRC I tried that at one time.
All it ever did was crash and corrupt .....

 

Ran out of gas before all my brain cells were killed. Still killed
enough to make further discourse with JB seem like a worthwhile effort.

Quote JB:
"C2 means that the tangent direction and the curvature of the surfaces
are
the same and like I said... VX can do this"

Well, gee-whiz, Jon. You shoulda said so in the first place.

Better stick to the conventional wisdom: Debating with JB and Cliff is
like running in the Special Olympics. No matter who wins, everyone
looks retarded. I should know better than to get between married
couples, anyhow.

 

I know there is an underlying mathematical definition for these conditions,
but most people here are not mathematicians or programmers, they are simply
users like myself, and they want to understand what these conditions mean in
therms of day to day applications - i.e. "Why is a curvature continuous
"joint" advantageous or not, where should I consider using these kinds of
tools?"

Yes, there need be joints, as it's not practical or desirable to build a
car, for example, out of one single surface... Beware of using "Patch" it's
a bit like "billet"... means different things to different people...

Yep. But the question is why? Aside from some esoteric application where a
degree 17 surface might theoretically be needed, most everyday things can
probably be designed with degree 1, 2, 3, and 5 surfaces.

--Mitch

 

Not as far as I know. He's always welcome to contribute, as long as he's
civil. Obviously, posting long rants about how bad Rhino is compared to
this or that other program on a Rhino sponsored ng populated by Rhino
fanatics is not going to win him any popularity contests... A little like
going into (insert your favorite ethnic neighborhood here) and shouting
(insert your favorite ethnic slur here) at the top of your lungs...

--Mitch

 

Poor jb has no clues what it would actually mean if it was correct.
OTOH He's just copying that stuff from what someone else once
said and has no clues what it's about.

 

Consider a surface of degree 3 that has 100 X 100 surface control
points .... how many patches?
What if you instead use 4 surfaces of, say, 50 X 50 points & degree
3? Degree 17?

As the degree increases so does the compute time to evaluate it.
But so does one's control over it.

Cubics are a fairly fast compromise.
But what happens if your system only supports cubics but your
data is degree 17 from system XYZ?
Do you get banqueritus?

BTW, Your underlying surface may be of degree 17 or whatever
but your surface *vsualized* as a cubic or polygon mesh.

What you *see* on the screen is not always what the surface
actually is. Or where.
Knowing this solves some CNC (and other) "verification" issues <G>.

 

Why is that important? If it's "a" surface, it's considered as one entity
in most programs, and manipulated as such...

The problem then becomes how to maintain the correct relationship between
the surfaces when the object is manipulated (streched, twisted, etc.)

Yep. BTW (another can o'worms about to be opened here), a large number of
CAM programs produce their 3D toolpaths using projections onto polygon
meshes made from the underlying surfaces...

 

Right, I can see the differences here, you are involved in making just
moulds, where I have to design and have to know about:-
worldwide standards and pressure directives
Stress analysis
Sheetmetal
Engineering
Microprocessors
Circuit board and wiring layouts
Pipework
Hydraulics
Workshop manuals
Operating manuals
Service parts and manuals
Sales literature
Basically everything from the idea to the finished working product, sales
department and then on to the servicing side.
All this with one sidekick!
Gee, must be great, just to have one job!
Blimey, I did't realize I done that much :-O, I must ask for another pay
rise

 

A rough curve, in the extreme may effectively fill the surface on
which it lies. Same logic applies to extremely convoluted surfaces
onto 3D. Then the 'roughness' can be thought as increasing the
dimension of the object.

http://parallel.hpc.unsw.edu.au/complex/tutorials/tutorial3.html
Fractal dimension
The notion of "fractional dimension" provides a way to measure how
rough fractal curves are. We normally consider lines to have a dimension of 1,
surfaces a dimension of 2 and solids a dimension of 3. However, a rough curve
(say) wanders around on a surface; in the extreme it may be so rough that it
effectively fills the surface on which it lies. Very convoluted surfaces,
such as a tree's foliage or the internal surfaces of lungs, may effectively
be three-dimensional structures. We can therefore think of roughness as an
increase in dimension: a rough curve has a dimension between 1 and 2, and a
rough surface has a dimension somewhere between 2 and 3. The dimension of a
fractal curve is a number that characterizes the way in which the measured
length between given points increases as scale decreases. Whilst the
topological dimension of a line is always 1 and that of a surface always 2,
the fractal dimension may be any real number between 1 and 2. The fractal
dimension D is defined by