closed lofts not symetrical

Hi there,
Has anyone else noticed how if you make a surface-loft between to closed sections which are symetrical about X and Y, for example a rounded
'ob-round', and use four guide curves, which are symetrical in pairs (one pair in the X plane and one pair in the Y plane) between the two set maintain tangency and advanced smoothing, this surface is not necessarily symetrical and tangent about X and Y. I have the base of a blow moulded bottle which I have constructed in such a way, then I've had to half the bottle and mirror the halves to avoid doubling my feature tree in some areas, and then the base is no longer tangent.
I guess a picture would help here, as I'm not being very articulate, but maybe someone else has seen this and has a comment.
Lee
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Lee,
I cant quite figure out what you mean, but I bet that if you study these tutorials it would help understand whats going on...
http://www.dimontegroup.com/tutorials.html
Good Luck
Todd

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Thanks Todd,
I have studied those tutorials already - and bloody good they are too! If I get time I'll sort out an example of what I mean.
Lee

(one
necessarily
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Sorry I couldnt help you more!!

closed
moulded
the
but
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I've seen that. I don't remember the fix, it was probably to do half of the loft with tangency and mirror it. If you can, you should send this example in.
Just some questions, were you using any end tangency controls? Any guide curves or centerlines? What types of sections? (2D/3D, faces, edges, curves, etc)
matt
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No, that's probably not the solution. Ed points out in one of the tutorials that lofts don't maintain tangency on the supposed centerline and explains why. I know from my own work that mirroring the part can make a break at the centerline. (On my parts the lack of tangency is small enough that no one notices.)
Jerry Steiger Tripod Data Systems
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I can't explain this, but I can think of a couple of things you might try. My first suggestion would be to give up on the mirroring and live with the longer feature tree. You could also try NOT using maintain tangency and/or advanced smoothing. Their behavior is not always very intuitive.
Jerry Steiger Tripod Data Systems
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Yep, seem it before and I'm trying to find the files which shown and see if they are still doing it. I would guess they still have this problem and it resurfaces or is a core problem? And, btw, the sketches I used are not mirrored sketches. Even today, the surface topology on my models change per release and service pack. i.e.,... INCONSISTENCY with the core programs math or parasolid?
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Yep, seen it before and I'm trying to find the files which I've shown and see if they are still doing this. I would guess SW still has this problem and will continue to have it? And, btw, the sketches I used in those examples are not mirrored sketches. Although, the mirrored sketches are one of the problems, even mirrored surfaces act differently.
And, even today, the surface topology on my models change per release and service pack.
.. no warm fuzzes knowing this at all but it continues.....
BTW, example, "Filled Surface" (n-side patch) is one of the most inconsistent features by far and if you use constraint curves, you chance of it failing are increased per release and sp!
Ah, yes, the INCONSISTENCY... is it the core programs math or parasolid itself?
SW Corp is making the experience of upgrading or migrating data to a new release or sp a very negative experience. When I have to repair my models per release and per sp, SOLIDWORKS is NOT a PRODUCTiVE Tool!
SW = BETAWORKS = WIP (work in progress).
And, btw, too you anal retentive prismatic engineers/designers, these inconsistencies are not limited features with shape (..curvy swoopy ergo thangs which are pleasing to the eye, functional and usually sell product to idiot users who normally could careless what is under the facade' and care more how to impress and add acceptable value to their psyc-society-esteem ego position).
..
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I, perhaps with less venom, agreee that aesthetics are important. When challenged on that statement by the technically minded, I ask 'why is your wife pretty, then? If function is more important than aesthetics, any old woman would do'. This of course puts the hapless engineer in the bind of admitting that aesthetics are important in their lives or that their wife is a 'dog', both of which cause red faces and terrific levels of discomfort.
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is
oooohh yeeeaaahhh
baby.
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Yeah, I got carried away with this. But it does disturb me (listening to the band Disturbed!) that people do not think the curvy stuff is needed or they have a resistance towards it. And my point is, to those who may think it is limited to curvy thangs, it's not.
For many of us, models with shape are a important part of our business. And, these inconsistencies are amplified when using curves and it's not pretty and it's not productive.
Reality = Sex sells Products need to to have a fresh, new, and sexy look to attract the buyers = Curvy tools will always be needed for design. And, those tools should be consistent for the designer/engineer to have repeatable or predictable control. (although, too be fair, I'll say that some of the inconsistency of the surfacing tools have given me some unintentional idea's, but that's totally by mistake)
The foundation of these issues come from the sketches used and symmetrical or mirrored conditions illustrate this problem more so. Will SW Corp ever fix these problems??????????
(now listening to Rage Against the Machine)...
The natural world is made up with some wonderful shapes and can't imagine sleeping with prismatic female (ok, that would be hell!).
.. ;^)
"Edward T Eaton" <ed1701this_is_all_anti-spam-garbage_after_the_1701> wrote in message

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Comment: Lofts are terribly demanding things. We provide lofts a couple of profiles, a couple of guide curves, and SW fills in a massive volume based on these minimal inputs. If we are a little shy on even one of the components of the loft, it all goes to pot. With every release, and sometimes with service packs, the rules on lofting change. I can not tell you the absolute sourceof your problem because I have too little information. But, yes, I have seen your issue with closed lofts.
Send me a copy at ed'ignorethebitbetweenthequotes' snipped-for-privacy@dimontegroup.com and I might be able to root it out. If you want general tips, here they are: 1)guide curves are 'almost' always a mistake. We do a fair amount of last-minute-fix-it work on other peoples' files, and the majority of the problems are solved by eliminating the guide curves and creating the loft 'naturally' (which might even take less set up than a guide curve loft). I have it on good authority that the devlopers are aware of the terrible issues relating to guides - and they may change things - but its going to be a while. 2)Guide curve order matters. The first guide curve drives the parameterization of the loft faces. If that guide curve is a little hinky, the loft is f***ed no matte what you do. 3)No matter what you do, guide curves take precedence over your loft sections. That should keep you up at night. If the loft feels the need, it will follow your guide curves and completely miss your sectrons. 4)I dont' even want to get into start tangency conditions, epecially when relating to closed lofts (strangely enough, there is no option to match the start tangency to the end tangency on a closed loft, in my expereince)
There are other issues. Again, I can't get into it all here.... please send me a sample. If requried, I will sign and NDA
,

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