converting an unusual shape to a solid

[jamesssydney]

To whom it may concern,

I'm having trouble creating a 3D solid from at the attached file. I've tried lofting and a few our techniques, but nothing seems to work. Of course the design has some unusual curves.

 

Any guidance would be much appreciated

 

Kind regards

 

James

3d object.dwg

[Chris.E_AllaboutCad.com]

Hi James,

 

I think this needs to be approached in parametric. Normally I would bring this over to 3Ds Max or Sketchup (Curviloft), then import back to CAD. 

 

So far, this is the best I can suggest for you, I approached it segment by segment (4 sides) then applied the EDGESURF tool for the mesh

 

Hope this helps, a bit!

 

Cheers,

Chris

 

[f700es]

Yeah but if you use SU and Curviloft and bring it back into AutoCAD it will not be a solid. Sort of defeats his request.

 

[ammobake]

rulesurf will do this as well - with the surftab command specifying the number of surface tabulations for each ruled surface.

and once that's drawn you can add smoothing in the properties to clean it up.

You would just have to draw the ruledsurfaces between each segment (for 8 total) and then apply color, textures if desired and surface smoothing to the desired extent.

 

One reason you might not be able to extrude or loft...

 

By default, the "SPLINETYPE" system variable in Autocad is set to "6" or Cubic.

But if you use "5" or Quadratic B-spline I recall it letting you loft and extrude to other objects.

 

I ran into this strangeness last year when I was using meshes to draw the skin of military aircraft in Autocad.

 

Cubic splines can twist in 3d space across multiple axes'.

 

But Quadratic B-splines can only twist and change direction along a single plane.

 

Because of this, Autocad can easily make sense of how to extrude the objects to other entities.

 

In fact, I think I remember reading about something with Quadratic splines where Autocad prevents extruding to/from them no matter what.

But I could be wrong on that.

 

ChriS