modeling a car

[boydt]

I want to model a car for a CAD class I'm taking. I know I'll need to use a lot of surface modeling, but have never worked with surfaces before much. Can anyone give me any starting tips on how I might use surfacing to create the exterior shape of the car? Should I be using free form surfaces? Or maybe lots of different datum curves/points? Thanks.

 

[dougr]

ISDX (style features) is probably best but boundary surfaces are good too.



Both of these use curves to create surfaces. ISDX curves are freeform but you must use a min of 4 curves per surface (at least as of 2001), boundary surfaces 2 curves or 1 curve plus a point/vertex.



Would suggest ISDX, it's more fun.



Also recommend you read up on surface merges. There's not much you can do in surfaces without using these...

 

[jabbadeus]

Yes, ISDX is the way to go.



For data management, I also recommend you research the use of skeleton models (provided you have the Advanced Assembly Extension; if not, you can use the master model technique) and Data Sharing features (e.g., Copy Geoms) to consolidate your design information in a central location and control change propagation.



David Martin

Torgon Industries

 

[gggggggggg]

Of course, if you don't have ISDX, which I'll bet you don't, considering you mentioned you are taking a class, don't worry. ISDX is certainly a great tool; very effecient, but you can still create anything you want with out it.



I would suggest you lower the bar a bit. Modeling a car on your first attempt with surfaces is a bit extreme. I would suggest you first learn how to model with surfaces. Then, maybe attempt to model something a little less grand than a car.



Also, remember that modeling with surfaces in Pro/E is not a seperate program, or a different kind of model, or anything like that. Surfaces are simply one more type of feature.



Lastly, I would suggest that you DO NOT use free form surfaces for your project. They are of very little use. I agree with Dougr, boundary surfaces are the way to go.

 

[miked]

Remember the surfaces are only as good as the curves they are built on. If want g2 surfaces your curves will also need to be g2. That may sound obvious but for sometimes people dont realise it.



Try this newsgrooup

http://forums.cardesignnews.com/6/ubb.x?a=frm&s=99560371&f=64460817

There are lots of autmotive guys in there that may be able to help you along.

Mike

 

[amoncur]

Thanks for all the suggestions. Are surface merges and boundary surfaces in wildfire, or are they previous edition names? If so, what are their equivelants in wildfire?

 

[miked]

In wildfire merge is under the edit menu

edit>merge

boundary surface is under the insert menu

insert>boundary blend (about half way down)

Mike

 

[amoncur]

How do you use the surface merge tool? I tried it with a few different scenerios and I'm not exactly sure what it does. I can only get it to merge two surfaces that are already touching, which is pointless because they're already touching, I don't need to merge them. Or is the merge is a necessary stepping stone to make the two surfaces tangent at the point they meet (which is what I'm really trying to figure out). Can someone point me in the right direction? Thanks a ton.

 

[dougr]

The surface merge joins two or more surfaces to form a single quilt.



Can be intersecting surfaces (merge by intersect) or just touching (both merge by join or merge by intersect).



To create a solid from quilt it is necessary to have a single, closed quilt (unless you're creating thin features) and the surface merge is the tool to do this.



Think of constructing a patchwork quilt.



Surface features are really only used in the construction of solid features.



After all, Pro/E is a solid modeling package.

 

[noppenbd]

When using boundary blend surfaces, there is an option to specify the boundary condition (tangent, normal, curvature continuous) at each specified boundary. Of course, the other boundary curves must agree with the condition you would like to specify.



This is the limitation of boundary surfaces, they are dependent on good curve creation. My suggestion for building curves is to use sketched curves for 2D curves and curves through points for 3D curves. When building curves through points tangency can be specified directly.

 

[noppenbd]

Another tool which is useful is the Datum Ribbon feature. You can use it to easily build a skeleton tangency surface based on a spine basic curve and as many side curves as you want. Then you can build your boundary surfaces tangent to the Ribbon.

 

[miked]

After all, Pro/E is a solid modeling package.



This brings up an interesting question (to me anyway).

How many people in this group use strictly surfaces and rarely if ever use solids?

Mike

 

[dougr]

Have noticed noticed some people on this site use a mix of both but fall short of creating the final use quilt solid.



When you think about it all datum features and surfaces provide construction functions for solid features.



Earl-da-Pearl



If you look closely at your surfaces before merging you'll see that the common edge is yellow. Yellow indicates an open edge, after merging you'll notice this same edge is white indicating that these surfaces have been merged.



Suggest you play with two intersecting surfaces rather than joined surfaces, things will become clearer.



What's the significance of Earl-da-Pearl ???

 

[gggggggggg]

miked,



I don' understand your question use strictly surfaces and rarely if ever use solids. Why would anyone do this? That would be like modeling only with datum curves, or modeling only with datum points. Surfaces are simply another feature used to create your end product, a solid.



Here is a scenario: Lets's model a cube! I'll do it with solids. There, I'm done! I extruded a 1 square a depth of 1. Done.



Now you do it with surfaces. Extrude a 1 square a depth of 1 (make sure you pick capped ends), then use the create protrusion use quilt command. Or, build 6 seperate flat surfaces, do 5 surface merges, then use quilt to make it solid. Does anyone see my point yet?



I don't get it when people ask this question about modeling with (or more incorrectly IN) surfaces. Surfaces are a feature, just like curves, points, datums planes, whatever.

 

[Brian_Adkins]

Some models never get to the point of being a solid. Many engineers and ID folks just get to a surface model and that is good enough. This is getting more frequent as more ID tools are being incorporated directly into Pro/E (e.g. some CDRS functionality becomes ISDX).



Anywhere that Pro/E is being used instead of other ID tools (Alias, Rhino, FormZ, etc.), you'll find people working with pure surface models.



Heck, I think I saw a post here last week about someone using Pro/Legacy to work on 3D wireframe models...



-Brian Adkins

 

[miked]

ggggggg,

I dont build cubes, I surface exterior automotive components for injection molding. I build almost everything in isdx which is not solids. I guess I didnt see making a surface model into a solid on the last feature as being solid modelling.



The tooling shops I deal with could care less if the model was solid and dont care if the surfs are merged or not. I do merge them except in rare occasions if Im in a hurry and Ive done things in the wrong order. For quick and dirty work its okay to have gaps as long as they are smaller than the cutter.



For consumer products I do the exterior surfaces and someone else builds the ribs and bosses etc.

Sorry for not making the question very clear.

Mike

 

[gggggggggg]

Mike,



I certainly didn't mean to say that you only model simple things. Sorry about that.



I've only used Pro/E for mechanical designs. I guess I didn't realize that there was a use for surface only models.

 

[design-engine]

I have a 75 Caprice Classic modeled in Pro/SURFACE and ISDX.
If you want the model email me your contact info and I will send you
the login and password.

Oh and a 350z too. This one is apart of our

G2 A-class modeling workshop.

http://www.proetools.com/courses/isdx/level7.htm








http://www.proetools.com
Edited by: design-engine

 

[miked]

Bart,


I worked on the z or GI about 3 years ago and have the original surfacesin anideas file (it doesnt have very many features other than an import from imageware) for the exterior. It would be interesting to see how close your model is to the real thing.


Where did you get the dims from?


Mike

 

[raj_1]

I have a 75 Caprice Classic modeled in Pro/SURFACE and ISDX. If you want the model email me your contact info and I will send you the login and password.

Oh and a 350 zx too.



Bart Brejcha
DESIGN-ENGINE|EDUCATION
http://www.proetools.com