Loft Guide Error

[fonz]

I'm trying to loft a profile between 3 circles and i have created 2 2d spline guides to loft through (see picture).

 

 

I get an error when i select the two splines as guides which says

 

"Modeling Operation Error:

The guide is not G1 between first and last sections.

The selected entities are not valid"

 

The guides are definitely touching the profile edges so I'm not sure what the problem is.

[fonz]

I've just been messing around with the loftnormals command. It was set to 1 so I changed it to 2 and i get a new error:

 

"Modeling Operation Error:

Access violation.

The selected entities are not valid."

[JD Mather]

Why didn't you simply attach the dwg file here?

Can you use tangent arcs for the guide curves?

If not, why not?

[fonz]

DWG attached and i'm not using arcs because I don't want to. I'm just getting used to CAD I would assume something like this is possible, there's no way in future i'm never going to use splines for this purpose.

Loft spline.dwg

[nestly]

I don't think 2 will work because your guides are not tangent to the circle cross-sections, 1 should work...

[rickh]

Loft spline.dwg

 

Like Nestly said, I set loftnormals back to 1...

 

then drew lines from the quadrant snaps of the circles, then drew splines to the line endpoints.

 

then loft worked fine. Maybe splines to quadrant would work fine too, I just like looking at the top view where I can't snap to the circles since they are in different planes.....

[nestly]

I didn't recreate the splines, but I did have to change them from "Show Control Vertices" to "Show Control Points"

[JD Mather]

... there's no way in future i'm never going to use splines for this purpose.

 

If you get serious about geometry like this - I recommend you investigate a modern 3D CAD program like Autodesk Inventor.

[fonz]

I've done everything you have suggested on my drawing, loftnormals=1 i redrew the splines to the quads of the circle but i still get the same error? yet on your version of the drawing i can perform the same function????

[nestly]

As per my profile information, I was using 2011, but I just tried it in 2012 and it does fail, so apparently they've changed something in 2012. The loft preview is a lot more detailed in 2012 vs 2011....

[Dadgad]

If you get serious about geometry like this - I recommend you investigate a modern 3D CAD program like Autodesk Inventor.

 

The OP might already have INVENTOR FUSION in his bag of tricks, as he is running Autocad 2012. It was included with my version of Autocad 2012 vanilla. Fonz look in your Autodesk program folder for INVENTOR FUSION, just in case you already have it, as it offers more advanced modeling tools and functions than regular Autocad vanilla.

[fonz]

Yes it's 2012 I'm using. Still, I was able to perform the loft when I opened up rickh's drawing, perhaps the problem is not with the loft but with the spline. This may be something for Autodesk support.

 

Thanks for your help

 

 

The OP might already have INVENTOR FUSION in his bag of tricks, as he is running Autocad 2012. It was included with my version of Autocad 2012 vanilla. Fonz look in your Autodesk program folder for INVENTOR FUSION, just in case you already have it, as it offers more advanced modeling tools and functions than regular Autocad vanilla.

 

Yes I have inventor fusion, I may start modelling in these in the future I'm just trying to get to grips with Autocad first.

 

Thanks

[ReMark]

I think you literally have to go back to the drawing board and redo your work. I don't see this as being a problem for AutoDesk Support.

[JD Mather]

.... INVENTOR FUSION, just in case you already have it, as it offers more advanced modeling tools and functions than regular Autocad vanilla.

 

And full Autodesk Inventor has more modeling tools and functions than the free Inventor Fusion. Especially for Splines and Loft.

[nestly]

@ ReMark

I dunno, AutoCAD2011 lofts along the original Spline guides using the default setting of LOFTNORMALS=1 ..... I can't get AutoCAD2012 to use the original spline paths at all....

 

I'm not sure that simply re-creating the splines will necessarily work. If the spline paths need to be a fixed shape, then there's really only one way to create them. The splines in ricks drawing are a completely different shape.

 

[fonz]

Ok problem solved.

 

Problem: Splines - I was drawing separate splines in between my 3 circle cross sections then joining them individually. Turns out you can't do this rather bizarrely.

 

The only reason I was doing this is because I'm working remotely on a laptop and the trackpad is a bit temperamental.

 

If anybody can explain why this is a problem however, I would like to know.

 

Thanks to everyone who has helped.

 

Regards

Fonz

[nestly]

Ok problem solved.

 

Problem: Splines - I was drawing separate splines in between my 3 circle cross sections then joining them individually. Turns out you can't do this rather bizarrely.

 

It may have something to do with the way the splines were created, but it's also a AutoCAD2012 thing, because 2011 will use the original splines as guides...

[rickh]

The splines in ricks drawing are a completely different shape.

 

I admit it, I cheated.

I just wanted to make sure the drawing could actually do the loft with spline guides (I couldn't get the original splines to work as guides for me so I drew my own).

[SLW210]

@ ReMark

I dunno, AutoCAD2011 lofts along the original Spline guides using the default setting of LOFTNORMALS=1 ..... I can't get AutoCAD2012 to use the original spline paths at all....

 

I'm not sure that simply re-creating the splines will necessarily work. If the spline paths need to be a fixed shape, then there's really only one way to create them. The splines in ricks drawing are a completely different shape.

 

 

Works fine here also on AutoCAD 2011, just changed LOFTNORMALS=1 and set Spline to change them from "Show Control Vertices" to "Show Control Points", as stated by nestly.

[3D generator]

As a possible workaround, you could create a spline curve through the center of the circles and use the path option in the loft command rather than the guide option. However, if you need the faces of the lofted surface to follow the original spline curves exactly, this might not suit your purposes.