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Question about advanced surfaces, splines and things that Varicad doesn't have.

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Question about advanced surfaces, splines and things that Varicad doesn't have.
Hello,

I'm trying Your version of VariCad 2010 2.03 on linux(32) and I'm very impressed.
But there are some things that can't be done in VariCad:

- ellipses
- splines
- creation of advanced surfaces based on splines

I've found program for creating surfaces: Art of Illusion version 2.8.1 and
it can export files in :

- povray V3.5 (.pov)
- VRML
- Wavefront (.obj)

I know that solids can be imported into VariCad by STEP files.
My question is: do You know any program that can transform above extensions into
STEP file. I'd like to use advanced surfaces in VariCad.

Cheers,
Maciej Los
advanced surfaces, splines
Hi Maciej,

We plan to improve the 2D module significantly, so the support for NURBS in 2D should be better soon. Also, we plan on implementing new possibilities of creation of 3D NURBS patches.

In 2D, you can create an interpolated NURBS curve of 3-rd degree. You have to select up to 48 (first limitation) points. There points are interpolated into NURBS. You can use such curve as a part of profile, which is then rotated or extruded into space. So you can create surfaces as rotated or extruded NURBS.

If you need to use NURBS as a part of the profile, you need to create it as a complete segment - not cut within parameters 0...1

As to the ellipses, there is a function creating ellipsis. However, if you need it as a curve for extrusion into space (for instance), you'd better create a NURBS according to it - select the interpolation points as points at the ellipsis. Use selection of line end-point. The ellipsis is replaced by set of short linear segments, the endpoints of these segments are located exactly at mathematically defined ellipsis.

You can also use the "Graph" function (GRA command) - it allows you to insert a graph, or a set of 2D points into 2D area. These points are loaded from a text file containing x, y coordinates. Then, you can select these points as interpolation points for NURBS.

In 3D, VariCAD supports working with NURBS patches - but for current versions, only internally. It means that you can insert a solid containing NURBS surfaces (insert from STEP), and then, you can work with it - for instance, perform Boolean operations.

Thanks for your interest, Maciej.

Best Regards
Marek
Reply
Hello,

I've found ellipses and splines. But I cannot extrude or rotate both.
Even if spline is closed.

I think about creating fuselage of a helicopter. I would need fluent transition from one rib to another. It would be best if I could choose all ribs in the operation. Path would be straight line but it would be good if you implemented such transition through any (spline) path.

Best Regards,
Maciej Los
Reply
Something like that can be done in Art of Illusion (java program). But I don't know how to change surface exported in that program to STEP. Any ideas?.

Thank You for answer.

Maciej Los
Rotation of the Elipse
Maciej,

1. Rotation (RSO command)

To create a solid by rotating a 2D profile (in this case, ellipse), please note that you need to rotate only half of the ellipse. (The surface is created just by rotation of the half of it.) So when you are creating the 2D profile (ellipse) for rotation, define the starting point of the ellipse "0" and end point "180".

BTW: In case of shafts created using the Shaft tool (SHA command) in 2D, you are offered an option "Create half-profile suitable for 3D rotation solid". You can give it a try to see how it works - the same principle is applied for other profiles as well.

2. Extrusion

In this case (to be able to extrude the profile) you need to have it closed. Then simply use the Extrude tool (ESO command) and follow the instructions in the status bar (define a height, select a profile, and define an insertion point)

Best Regards
Marek
Reply
Ad. 1

OK, rotation of ellipse is working and creation of shaft in 3D is just wonderful.
But when I try to rotate spline I get information: 'Profiles intersect'.

Ad. 2

I can extrude ellipse and it's working fine but when I try to extrude two splines
offseted by some value and connected with lines (it's a closed shape) I get message: 'Profiles intersect' and that can't be done.

With Best Regards,
Maciej Los
File needed
Such an error is displayed, for example, when there are some elements of the profile laying over each other. Please send your file to support@varicad.com so that we can look into the cause, and suggest how to correct it. Thank you.

Best Regards
Marek

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