Complex 3-D Geometry

[Marmight]

I am attempting to design the body an injection moulded wrist worn watch.

In order to increase the aesthetics of the product, I have tried using a 3D sketch to create an three dimensional outline of the unit to make its appearance less blocky. I then use Boundary Surfaces and Surface Knit to turn it into a solid, then use Extruded Cuts to hollow it out and add other similar details.

The issue is that my 3D sketch is extremely unstable, seemingly reaching a critical mass of complexity where any addition or change to the sketch results in over constrained or unsolvable geometry. I would estimate their are approximately 100 sketch entities in the 3D sketch. I have tried deleting all relations in the relations manager, and "Fix"ing all the sketch entities, but this is obviously not an ideal solution.

I presume that this design methodology is not very good. Does anyone have any advice, or articles they could link to on proper 3D design practises for complex shapes?

 

[TheTick]

Break your sketch into smaller pieces. Perhaps drive the 3D sketch from one or two 2D sketches to that define face and profile.

 

[SnowCrash]

Do not reject the idea of restraining your 3D sketches. I have worked on a project which featured 2D sketches with many elements. There was no success with this until all elements were constrained. Features and geometry would change at any time.
If you can project your elements between 2D sketches that will be more stable and controllable, too.


--
Hardie "Crashj" Johnson
SW 2011 SP 4.0
HP Pavillion Elite HPE
W7 Pro, Nvidia Quaddro FX580

 

[Eltron]

I've seen the same problem with complicated 2D sketches, especially with splines. Just split it up as best you can as TheTick suggests.

Dan

http://www.eltronresearch.com

Dan's Blog

 

[rollupswx]

I always use 2D sketches to create and control my 3D sketches.
Search Google for Ed Eaton Curvy Stuff Tutorials Dimonte Group, and also Mike Wilson SolidWorks and these older tutorials.

http://home.pct.edu/~jmather/content/DSG322/SolidWorks_surface_tutorials.htm

 

[moon161]

SWX helpdesk reps have recommended to me to keep it under around 30 elements in a sketch for good fun & stability. 100 elements sounds about right for crashing or locking up a single sketch.

I think trying to do it all in one sketch is a problematic approach for a few reasons:
Model stability becomes an all or nothing problem.
It's a house of cards when you try and change something.
Hard to use configurations & design tables.
Hard to make & compare variations by turning features on & off.

 

[kellnerp]

Solving constraints in 3D sketches is much more complicated behind the scenes. Keep it simple and use more sketches.

TOP
CSWP, BSSE

http://www.engtran.com

http://www.niswug.org

http://www.linkedin.com/in/engineeringtransport

"Node news is good news."

 

[Marmight]

Thanks for the advise everyone.

I broke up the sketch into 6 2D sketches, and the design is now far more robust and easier to edit.

Thanks everyone!