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AC Cobra 427 Surface is to big!

C

Cobra289

New member
Hi,

I have a hobby that is a AC Cobra 427 "Replica" I have model all most all the parts, like chassis, suspension, etc.
I did put my self for the difficult task of modeling the AC Cobra body, after many hours and lot os disappointing moments I have a AC Cobra body, but........

The body is made from surfaces and most of all the sketch are 3D the end result can be improved but the worse case is that the model is now 380Mb big and I can't use for the total Cobra assembly, SW crash (memory)

I have an internal memory of 2500Mb and the XP has the switch of 3Gb set. SW-2007

Is there a way to solve this problem, or put in other way, has someone made a AC Cobra body that is small, say around the 3 Mb file?

I also have translate some mesh model and I get and small file (Imported Surface) but I can't do anything with it! The surface is just a mesh!.

Feature Sadistic:
Features 209
Solids 0
Surfaces 37
Check entity say: No invalid edges/faces found. 37 open surface(s) found.

Here is a picture of the model of 380Mb.
best_body01.jpg

cobra_30.jpg

COBRA_32.jpg


Please help!
I am not and expert just a man with a hobby and a ridiculous amount of patient!

Best regards,
 
Hi,

Thanks for the compliment "burnsp"

"Design-Engine" (Bart)

Here is the link to the Mesh surface model.
http://www.donostia.demon.nl/LARGE/MESH_01.SLDPRT

Or do you like the bad designed one that I made? It is very large so I was forced to load at a different site.
http://www.cobratech.nl/BEST_BODY.SLDPRT

It will take a wile to load!

Thanks for your interest! your site show a lot of nice surface models, I hope that you can help me.
The big file hold the imported surface too, I did use it as a reference.

Regards,
Cobra289




Edited by: Cobra289
 
Hi there,
I am back, I did spend a bit of time changing the surface model. Now it becomes almost impossible without having a crash of SW 2007.

Bart I am impress with the way you working with surfaces, for me this is my first time to work at surfaces and as you can see I have choose one of the difficult's shape to learn. The Cobras has to much rounded shapes.

In your YOUTUBE videos you talk about reverse engineering, but in my case is the "Revision" engineering.

I wonder how you can combine the handles to a master one to having a direct change of size and shape in SolidWorks.
I need to investigate this area to make things more easy to revise.

I did register the forum that you did point and will follow with interest their ideas, but as you have see from my model I am in a level where I can't permit my self to have a serious discussion.

I supose that you have laugh with my infantile way of modeling, perhaps you can give me some directions and some valuable advises.

I have found a method to export the surfaces, I did select all the body (surfaces) and did "insert as a new part" (right click of the mouse) the model went from 370 Mb to 15 Mb and now I can insert it in my assembly.
It remains dependent of the large model and you can't change it but at least you can view it in the total assembly.

Well, let me know!

Regards,
Cobra289 (Carlos)




Edited by: Cobra289
 
First things first; about surface modeling - Solidworks, like most common 3-d modeling software, retains a history tree of each feature. This is nice for most simple 3-d solid modeling. projects.Free-form surface modeling is a different animal than extruding rectangular blocks and putting a few radii on them. Thefeature history tree eats up lots of memory and free-form surfaceseat more.


In surface modeling terms, a surface patch can be described as being "heavy", or "light". A flat rectangular surfaceplane is a "light" surface because it can be defined with four lines in one sketch place. On the other hand, a free-form surface that has tangency and continuitywith surrounding surface patches is general described as a "heavy" surface; meaning that its definition required a lot of geometry to describe its shape in context to the surrounding patches. Heavy surfaces consume more memory than light ones.


After you have a major section of your surfacemodel completed, or a heavy patch shapedthe way you want it, it is wise to save that section as a seperate part file; first stripping away the history tree by saving in para-solid format, or iges, or any neutral format. Then import back into your base design as a separate piece part.


I have been doing surface modeling for more than two decades, and started before parametric modeling software became popular. I can't think of any job I've done recently where I could have completed the design if I tried to maintain the feature build tree - it eats memory needed for free-form surfacing.


But, here's the kicker; its easier and faster to do surface modeling without a feature tree. While the feature tree is a nice idea for 95% of the 3-d modeling world, in surface modeling its actually a little bothersome to go through the ordeal of saving portions of a design in a neutral format to get rid of the history tree to fee up memory.


Your body model is not overly complex. If you do as I say, I suspect you'll find that yoursurface designis actually about a 5meg file.
 
Metoo said:
On the other hand, a free-form surface that has tangency and continuitywith surrounding surface patches.






Your body model is not overly complex. If you do as I say, I suspect you'll find that yoursurface designis actually about a 5meg file.
Click to expand...

Hi Metoo,

I have done the export as a parasolid and indeed the model when to 3Mb.
But I did from the total body and has 45 gaps that can't be repair.

So I think that the way you mention, patch by patch would be the best to do. But that means for me a total rebuild of the surface.
I need to find out if by suppress patches in the tree I can do your trick of export bit by bit.

I have a question regarding the "tangency and the continuity" how do you take care that the next surface has the right continuity?
I get gaps between two surfaces just because the curves have a different tension.

Sorry that I ask probably a beginners question, but I like to have this model right, time would be not a problem neither the enthusiasm but it is just the lack of knowledge. And off course the edge counts too, "It is difficult to learn a new trick to a 53 years old man"

Thanks for your information.
Regards,
Cobra289 (Carlos)
 
I'll give you a round-about answer, and then some pointers, because you hit on what defines the difference between a $30/hr design engineer who knows how to extrude and radius solids, and a $100/hr design engineer who does class A surface modeling.


The basis for creating surfaces is the same in all modeling packages that have the capability. Some offer more capabilities than others, but the fundamental way surfaces are defined from a software perspective is the same - they are all rectangular, even if the rectangles have twists to them. You might not see a rectangle, but rest assured, every surface you created on your model is retangular. What you visually see on the scene of your computer are the trimmed patches of these rectangular surfaces. Nothing is actually trimmed off the rectangular surfaces, but the software only reveals to you that portion you define as visiable. To see an example of what I'm explaining, cut a three or five sided hole in your design. Use the Fill tool, set to tangent, and make sure preview is on. In the preview screen you'll see the software create a rectangular shaped patch that best fits the opening, and when you select ok, only that portion of the filled patch inside the boundry is left visible.


When you create surface patches, constrain all four sides (two rails and two guides). If the modeling software is not capable of creating the patch with tangency and continuity to surrounding patches, then add enough rails and guides to suffice. Lastly, make sure the patches can be stiched (seamed, sewed, knit, etc, etc..) together. If not, go back and fix problem. Some modeling softwares allow you to set the max width of a gap for sewing patches. This is helpful, but it is better to take care of problem by design.


Surfacing is like playing chest; you always have to think about how the current patch you're creating will fit into the nect one you have to do - you can only twist and bend a retangular grid of U-V lines so much before wrinkles, stretches, and gapsappear.
 
Hi Metoo,

Your words are gold!
This confirms that what I am doing goes in the right way.
Plan the strategy of the build is the most important of the surface design.
I have experience this in the last two weeks.
Now that I see the initial model I need to laugh of the simple way of thinking but it has give me the base for the Strategy plan.

Right now I am re-building it to minimize the amount of faces (something that I learn by doing) I did have the bad manner of building a sketch out of different sections and that give me the split surfaces, I am almost there of removing that.

Once I have it the way I like (size should be correct) I will start all over again and use your trick of export surface by surface as a parasolid.

I have removed the initial "knit" that I made, just because my feature tree did grows and grows, but now that I have reduced to a minimum it will be time to use it and get rid of the glitches.
Sometimes I use the Zebra option to see how the lines flow but I think that I need to find out more in detail this option.

I did found your example during the build of the rear lights surface, the first thing that I did observe during preview was the added surface outside my oval shape, so I did select fill inside the boundary and the surface was made.
Funny a 3D that works just flat!

Strude and radius solids is not bad, in particular when you make simulations of movements, that real fun, I did that with the Cobra suspension, front and rear and I think that once I have done this body I will check if I can find a way to check and plot-out the "Bumpsteer" of the Cobra.
Also I need to check and find out a way to get the movement simulation of a torsion-bar but that is for later.

Indeed I have experienced, that the surfaces are the most difficult part of my Cobra build.

Here is a screen shot of the first re-build.
Surface_Bodies_58.jpg


Thanks for your time, I appreciate that.

Best regards,
Cobra289 (Carlos)



Edited by: Cobra289
 
Try using the Insert Part option to insert your Model's surfaces into a new part. because this doesn't bring the full feature information into the model it will reduce file size. However any changes to the original model will show up in the Part you created from the base model using insert Part.

Insert Part lets you Bring any combination of Solids Surfaces Datums and sketches into a new Part and is a good way to do Top Down design in SolidWorks. Improvements can and mmost likely will be made to this functionality but right now it works pretty well and has satisfied most of my Top-Down design expectations.

Michael
 
Hi,
I have found a solution to handle the big surface, read here bellow.

I use the insert Part option too and it is pretty nice option when you still need to make changes to the model.

But the big help to make the changes at the BIG MODEL was found by removing the ADD-IN "PhotoWorks"
Previously I did remove all surface materials but that was not much gain because SW use a base material for the model.

After remove the option of Photoworks from the add-in also the Start-Up my model went from 460 Mb till 180 Mb but the most important was to see how the Windows Taskmanager memory use, original was around the 2050Mb but now is only 450Mb.
That makes that I can save now the model in less than one minute compared to the 10 or more minutes from before the change.

I am pretty happy because I can now continue with the improvements without frustration time.

I hope that this helps someone.

Regards,
Cobra289


Edited by: Cobra289
 
normanvannorden said:
Geen expert? lijkt er anders verdacht veel op.


Mooi werk, ook ik moest t gewoon ff kwijt.
Click to expand...

Hi Norman,

Many thanks for the compliment, really I am not an expert. I just like my Cobra to much and put there a lot of effort.

You know persistence help a lot!Regards,
Cobra289
www.donostia.demon.nl
 
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