Problem with extruding/offseting a complex surface

[twozniak]

Hi,

i need to create a solid by extruding/offseting a spline surface  (attached picture). The problem is, a solid created by simply extruding this surface "outside" would cross itself, so autocad does not allow me to do it (neither extruding, surface offsetting is working) I tried to make a cube then using this surface as a splitting spline - however a solid created this way is flat on z-axis. How can I do this ? Everything is fine with the spline as well as a surface - it's closed one. Obviously the problem is in the fact in the self intersection of the extruded solid. So maybe using it to split a solid is a better approach?

I would appreciate any help, i am sitting on this for almost 2 days now.

Thanks in advance

[Patchy]

Try making a REGION first

[nestly2]

PRESSPULL will likely extrude it into a solid since PRESSPULL's first function is to create a region (as per Patchy's advice)

You may also try BPOLY (aka BOUNDARY command)  to create a new boundary without the "self-Intersecting" condition.

[twozniak]

REGION on what? The spline? It doesn't work since the spline is not z-axis flat. Why would i want it to extrude the surface anyway? (Note i want the surface to extrude in the direction of the normal vector to every point on the surface...something what surface offset does...)

[twozniak]

PRESSPULL does not wotk. BOUNDARY also. The spline is not 2D, as i mentioned in the OP.

[Patchy]

[nestly2]

Maybe post the drawing with your spline, and more detail about what you're trying to accomplish.  The screenshot looks like you're modeling a guitar body, in which case the suggestions already posted should be applicable to a logical workflow.

[twozniak]

I want to extrude that green surface in the directions showed by arrows on the picture to get a solid. There is a function that does that, it's called _SURFOFFSET. The spline you're asking is the red one on the picture. What i want to accomplish is actually a second floor of the audience balconies in a concert hall. I hope it is clear now.

[nestly2]

Perhaps try to THICKEN the surface.... or OFFSET the spline and subtract the resulting extruded solids?

[Alfred.NESWADBA]

Hi,

>> I want to extrude that green surface in the directions showed by arrows on the picture to get a solid.

>> There is a function that does that, it's called _SURFOFFSET

Sorry if I misunderstand something, but _SURFOFFSET with option "_SOLID" creates a solid. So what's the question?

From your very first post:

>> The problem is, a solid created by simply extruding this surface "outside" would cross itself

If that is the question then split (_BREAK) your spline into 2 pieces, create then 2 solids and run command _UNION.

- alfred -