Lofting with 3dpolylines or (3d)splines as guides

[marko_ribar]

I have problem while working with loft command.

I have defined shape and managed to place 3dpolyline in edges of shape (shape is rectangle, and 3dpline is spiral-helix with done segmentation) ...
While trying to do loft command, AutoCAD 2008 tells invalid guides, or can't complete operation...

If done with only one guide, or used loft with direction curve it does job, but result is the same as doing extrude-path...(while trying to preserve twisting shape along path)

If done with helix as guides, it finishes OK. (4 helix as guides, rectangle as shape - result : non twisted solid is made)

Why are 3dplines invalid objects for this operation, this is also for splines in 3D?

I prefer working with 3dplines or splines in 3D, can this be solved?

Also, when I try to do union (solid element operations) with lofted objects selected, operation can't be finished, why? (probably too complex objects are selected?)

Can extrude by path be done without twisting shape along path, or this must be done with loft command?

marko_ribar@yahoo.com

[JD Mather]

Zip and post the file.

[AutoCAD-Adviser]

Tell me exactly what you want to create, then I can better help you.

One advice: Don't try to combine a closed rectangle with a open 3D polyline in the Loft command. Only combine a open 3D polyline with a open 3D polyline. Alternatively, you can use 2 closed rectangles or 2 closed 3D polylines in the Loft command.

[marko_ribar]

Hi there, its me again...

My problem is this :
I try to solve job for calculating land works around positioned object (way, house, or similar)...
My thinking was that I can create open 3dpline around object until object cuts terrain where ground works changes (adding - removing terrain). With my *.lsp routine I was able to position all profiles along path and do lofting and it works. But when trying to union or subtract lofted solid with lofted solid-terrain it can't complete operation...

Maybe I need stronger PC, I don't know?
Or it is simply impossible to do this this way?

If you have time, or have some opinion post me (I can send you my *.lsp although it talks on Serbian language, but it is all easy to understand - it asks for angle of slope 1:X, so it can draw profile (triangle positioned horizontal), and then asks weather it is add or subtracting solid to create, so it can put shapes downward or upward and then it creates lofted solid;...also it asks for nearby center of curve of 3dpline, so it can put shapes on one correct side of 3dpline)...

[marko_ribar]

Hi...

It seems that solid element operations are working (last night I did it), but still has no solutions for making non-twisted loft solid by selected shape along 3dpline (all *.lsp that I made are near good result, but it seems that near vertexes shape can't be correctly positioned so I have many solutions from witch some don't work (union 2 lofted objects with nearly same result). Here are *.lsp-s

Bye, and thanks for advice you gave for lofting...

[jvicario]

Look at this web site: http://a-cad-emia.blogspot.com/2011/04/helices.html