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Automotive styling, hard edge fade outs and shelling.

    
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Mark

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Message 1 of 28

 Automotive styling, hard edge fade outs and shelling.
18-09-2009 10:03 . am   |   View his/her posts only
I have created some OK surfaces in VX in the past, but looking at some automotive body features where hard eges blend into smooth surfaces or two different surfaces blend into one and look tangential, what are the tricks to do this in VX and allow it to shell?, or at least do it in the first place? does anyone know of any tutorials for other systems that may be applied to VX?
If I am rambling, perhaps I should post some examples!

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Mike

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Message 2 of 28

18-09-2009 11:21 . am   |   View his/her posts only
the MIB, please send me a file to look at.

There are three ways of blending.

1. no tangency
2. tangency
3. curvature

On the last two there is a difference in how the radius-of-curvature is applied. Tangent blending can have a very abrupt change in the radius-of-curvature where the curvature blending has a smoother transition. Smoother transition is better for automotive because of how light is refracted.

I'm not clear on how this affects SHELL. The biggest limitation on SHELL is that the thickness must be less than the smallest radius in the shape.

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Randy

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Message 3 of 28

18-09-2009 03:12 . pm   |   View his/her posts only
MIB,
I'm not saying you're rambling but posting some examples would help.

This may not apply but I've attached a VX model that uses Bi rail loft.
If you're not familiar with it, Bi rail loft works well for transitioning from sharp to smooth tangents.

There are basic instruction in VX Help but I found the best way to learn this application is by experimenting with it.
It's been my experience that complicated shapes usually require lots of "experimenting".
Details like closed boundaries, Curve selection sequence, Connection points, can all effect a successful outcome of a Bi rail surface.

Of course as Mike mentioned Shell is limited by radius size. In that case I would apply creative modeling techniques, most commonly referred to as "The Fudge Factor"

Randy

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Paul

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Message 4 of 28

20-09-2009 05:48 . pm   |   View his/her posts only
Hi Randy,
examples are great. Since this is a forum here are some further tips you may already know.

You did not need to duplicate the sketches, You could extrude the initial sketch open ended and use the resulting wireframe edges for your path/guide lines. This cuts out surplus plane and sketch creations.
Further you could eliminate the remaining plane creations by drawing on the same XY plane then moving the sketch to the new location. This is easier to redefine than a plane location IMHO.
Using open ended surfaces/extrudes for lofts ensures surface tangency. You delete the start surfaces later and still have the nice tangent loft.

I am guessing the surfaces MIB is talking about are crease blends where two initially offset surfaces blend into one. Creating the two or three surfaces is OK, but how to do the runout blend between them?

Keen to see the answer myself.

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Mark

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Message 5 of 28

01-10-2009 05:26 . am   |   View his/her posts only
http://www.giro.com/en-us/products/snow-helmets/ember/
http://www.giro.com/en-us/products/snow-helmets/seam-audio/

Most car bonnets, panels,

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Paul

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Message 6 of 28

01-10-2009 05:11 . pm   |   View his/her posts only
Hi Mark,
this is a question that has been asked before on the forum and unanswered......

I think it is a definite case for a sample model from the Topology guys at VX.
We don't need a SnT at this stage, just a sample file showing the methodology used. I am sure stepping through the file we will get the idea.
If a video with audio is done even better, but I'd be happy with a file... can always ask questions.

I am really keen to see this.

Cheers

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Mark

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Message 7 of 28

02-10-2009 09:12 . am   |   View his/her posts only
I have done some of this stuff on simple spheres, but not on more complex surfaces, im sure a lot of effort put in would achieve something but im not 100% sure. Part002

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Robert

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Message 8 of 28

06-10-2009 12:32 . pm   |   View his/her posts only
Unfortunately, I couldn't open your file.

I'd be happy to involve the geometry-guys if someone gives me more than words (sounds like a song).

bobf

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ChrisWard2k2

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Registered: 2011-11-22

Message 9 of 28

06-10-2009 01:09 . pm   |   View his/her posts only
Hello the MIB

The basic methods you have used in the three sample models look to be a reasonable approach - I think your results look good. On a more complex 'host' Shape, you may not be able to Shell, but you will be able to Boolean subtract and in the process vary the thickness where required. Of course the only true test is to work with your real schematic Shape.

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Randy

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Message 10 of 28

06-10-2009 03:08 . pm   |   View his/her posts only
To quote Mark Twain there's "more than one way to skin a cat". Here's one more example to look at.
Randy

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Paul

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Message 11 of 28

06-10-2009 10:16 . pm   |   View his/her posts only
Hi Bob, not sure what files you couldn't open.
Here is a photo of the helmet referred to. In truth the curvature on this example is not great(could be the molding process of the thin shell or poor modelling or something else...) but the idea is well represented.
The issue is the primary(outer) surface heads in at least two seperate directions as features are encountered. It is this aspect that is intriguing.
I hope this is clear.

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ChrisWard2k2

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Message 12 of 28

07-10-2009 07:24 . am   |   View his/her posts only
You can see that the 'not great' bits could be on-mould corrections. Mould fettling is a skill, if the engineer is good at it, the product appearance can be enhanced.... At the rear of the helmet it looks as though there has been some shrinkage. So, mostly manufacturing glitches but of course brought about by the design complexity.

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Mark

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Message 13 of 28

07-10-2009 09:49 . am   |   View his/her posts only
Hello Mudcrab, I enjoyed reviewing your file, but there it does not have the example I was trying to get across where multiple level surfaces seem to blend back in together.
My file had some simple examples that worked, I will have to try with some more complex geometry where I am not so sure it will be easy or possible.

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Paul

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Message 14 of 28

07-10-2009 03:45 . pm   |   View his/her posts only
Hi Mark,
now I'm with Bob, can you please post some pictures of example surfaces - or objects that do what you want?

In the helmet, there is a 'common' surface that tangentially blends with a number of other surfaces that diverge to various non paralleloffsets and shape outlines. A lot of auto panels do this. Push an pull free surface modelers (Rhino, Blender etc.) can achieve this with relative ease, however, as far as I can tell, there is no parametric control as such.
So I am very interested to see how VX would approach this type of problem.

As a designer I often take a close look at how products are shaped. In a shop I have habit of running my fingers over shapes to see how they are modeled. IMO it is very common to see the designer is limited by his tools or his knowledge of them. A LOT is done with fillets when lofts would do a nicer job. To me this appears is either an economy of time or the limitations I have suggested. Otherwise there are a lot of designers with limited imaginations.
Right now I am prepared to say I am limited my my knowledge of VX.

Cheers

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Paul

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Message 15 of 28

07-10-2009 05:09 . pm   |   View his/her posts only
FYI here is a better example of divergent tangent surfaces.
Cheers

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Mark

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Message 16 of 28

08-10-2009 04:57 . am   |   View his/her posts only

Here is the first example I came across. fileted surface blends.
I will add as I find them, never there when you want one!

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Kevin

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Message 17 of 28

08-10-2009 05:28 . am   |   View his/her posts only
Would you believe it but I actually have and IGES file of that very door.....of course I cannot share it but let's just say that as it was modelled in CATIA the fade surfaces are 4 sided surface patches. The main "sharp" edge is actually a G2 spline edge that transitions into the flatter main door panel. This is not slash and burn modelling, but precision surfacing. In other words not a 5 minute job. Transitions like that can be achieved in apps like SolidWorks and VX using a patch surface or a boundary type surface with G2 edge constraints.

As an example of the technique I think was used on the door see Item number 4 on this blog entry http://www.dezignstuff.com/blog/?p=2550

For those that don't know, this is the no holds barred blog of Matt Lombard - a SolidWorks guru and author of a couple of best selling SW books. Matt's style is a bit abrasive sometimes but he tells it how he sees it - warts and all and has a fairly large following amongst the SolidWorks user community. All the techniques on that blog post could be applied to VX I think.

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Mark

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Message 18 of 28

08-10-2009 06:35 . am   |   View his/her posts only
Hello Kevin, thanks for the link.
Interesting read, again a lot of those examples are done on spheres, spherical shapes, but not on a more general complex shape where the curvature varies in both directions, or constantly changing radii or curved surfaces where each intersection is different and not an arc. Moving on from a sphere to an ellipsoid would be the next move. Ill try more tomorrow!

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Randy

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Message 19 of 28

08-10-2009 12:20 . pm   |   View his/her posts only
theMIB,
Many of us in the forum create the type of features you've described on a daily basis. The helmet appears to be a fairly basic free form shape (of which because of symmetry only half is required) with offset reliefs, drafted pockets, and relatively large blends. All of which a moderately experienced user should have good success creating in VX.

Per your original request for any tricks, I'd be glad to contribute what I've learned over the years but like most of us here I have limited time to make up examples of what I feel would help you. If you could just attach a model such as the basic free form shape with some problem areas constructed, I'm sure there are many here with some great tips for you.

The file "bi_rail_loft2" which I posted on 10/6 does contain many of the type features required to construct the helmet in your picture. Note the intersection of 3 surfaces and 3 fillets all created on a free form bi-rail loft shape. I've found that VX works as well if not better on these type features than a lot of high end software I've used.
Randy

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Mark

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Message 20 of 28

08-10-2009 02:50 . pm   |   View his/her posts only
Hello Wasamer1.
Thanks for the post and understand the lack of time!.
My examples depended on a filleted remove.
I know that this wont work for all examples thus my post
Ill check your file again tomorrow and report back.
Im not a new user to CAD or VX but have less time these days to hone my skills, need a new challenge where i can.
The ultimate would be a complex cycle helmet or car panels.
Im on my third helmet, my first with blends and my second cheating.
To me VX is the best of what I know and I hope this thread gets us all interacting.

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Paul

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Message 21 of 28

08-10-2009 03:12 . pm   |   View his/her posts only
Hi Mark,
why don't you post the base helmet file complete with some example indentation profiles as sketches and let a few of us come back with solutions. This way we can all have our minds expanded a bit more. We can always scale the helmet to fit the new mind size.
I'd be hopeful we can do better than the 0.02deg surface continuity error the SWX examples are left with. Hmmm , there's a challenge!
And for senior moment Mike, the email notification tip is a good one.

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Paul

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Message 22 of 28

12-10-2009 07:50 . pm   |   View his/her posts only
Hi Guys,
Here is a file and some pics with a base surface on it and an attempt to do the divergent surface thing.
I am sure a lot of refinement can be done but it's one approach.
Please feel fee to use this surface as a base for demonstrating other ways of achieving this...
I tried with morphing for a while and got some very interesting results. I am sure there is potential there, but I am a rookie and just maybe the morph would need some work to do we are trying here. Maybe Bob can tell us the answer....?
I'd love to see some good morph examples. Maybe a new thread for morphs rather than this one doing the pupae thing...!
Worst continuity is 0.028 at two locations. So it's close. If anyone can sort that then, show me how. I sorta ran out of time and have to earn a dollar.
(Excuse the original surface development mess, was experimenting with some other ideas as well. )

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Kevin

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Message 23 of 28

13-10-2009 02:30 . am   |   View his/her posts only
Nice examples there! I wouldn't get too hung up on a continuity "error" of 0.028 degrees. In real terms for a moulded product (and bear in mind the parts will be machined) you won't notice this. FYI I've done a continuity analysis on that Gallardo door skin and in the fade out areas it is reporting 0.03 degrees.

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Thomas

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Message 24 of 28

14-10-2009 08:30 . am   |   View his/her posts only
Hello

I looked to your good ideas.I have another procedure to get a good result. Generate the face with an sweep an variable scaling in X or Y or Z the sketch. Sometimes I use this procedure.
Have a look to the file and start by Backup1 in the history.


Thomas Reiff

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Paul

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Message 25 of 28

14-10-2009 05:37 . pm   |   View his/her posts only
Hi Thomas,
interesting approach. I little harder with compound surfaces tho'.

The problem with sweep is getting the surface continuity.
So in the attached file, I have taken the idea in a different direction using sweep as an easy way of getting a surface in place then using these to develop from.
I love loft since it does a great job of achieving beautiful blends.
I just wish there were some edge blend controls options in drive curve and birail.

Fillets struggle in the pointy corner department do we need a trick to bypass the corner.
IMO The trick is to trim well inside the corner and let the patches recreate the transition.

In the part, Base10, I use different methods to patch. Neither give a perfect solution.
You can experiment and see if you can improve the face continuity or someone else can advise how to get a better result.
(FYI Surface Continuity check is via Inquire/Face/Continuity - wireframe is best. Faces must be sewn)

What I like about this approach is the flexibility available with the divergent surface profile/paths.
Even better in V14 with the tangent spline to curve constraint.
Once could even set up a fully equation driven process.

IMO this goes further than the examples on the designstuff.com blog.


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Kevin

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Message 26 of 28

15-10-2009 04:44 . am   |   View his/her posts only
Another video demo to learn from showing another option.....

http://www.solidthinking.com/online_learning/vacuum.html

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Mark

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Message 27 of 28

15-10-2009 04:45 . am   |   View his/her posts only
Thanks for all of your examples.
Really interesting going through each one, have definitely moved forward with this.

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Paul

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Message 28 of 28

15-10-2009 04:00 . pm   |   View his/her posts only
Hi Kevin,
yeap can be done with 4 curves as they say.
The big difference 'tween VX and SThink is the parametric... which makes the process a bit slower BUT
eminently more valuable when serious design is taking place.
This exercise reminded me about the Scale tool in VX which is parametric AND can be linked to an expression/variable.
Meaning we can play with a few numbers once set up and see how it works. Very cool.

I did the file in V14 but cannot save it so have posted a screenshot.
Note the scale variable which is used by the first scale after the revolve.
See also
X