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# CV (Knot) Snap in X Form

Pioneer

Hi,

Another day another issue.

I'm still trying to get a grasp of what Alias Surfacing funtionalities are morrored in NX and which are not.

One very simple thing is the CV (Knot) Snap. It's a basic functionality in Alias allowing one to snap a control point to the grid (basically useless and irrelevant for NX as there is no grid) to the WCS Planes or to points, curves, edges etc.

What I want to do is - I'm working on some sufaces which ar derivative of complex geometries. I want to reduce the complexity so I remove all Spans (Patches). I also remove one half of a symmetric part to further simplify (and just mirror in one operation at the very end).

Naturally I notice that the second row of control points from the edge on which I want to have symmetry vary from the first row. (As you know if they are aligned we have a G1 Continuity and in case of symmetry that's all you need to have G2 along this edge after the mirror.)
Now in Alias I would just align the view to the symmetry plane and snap the CVs in x and then y (up/down and sideways, but not in z - closer/further). Done (and mathematically perfect). I don't think I can do this in NX10 (I got it to work by doing it manually, but it bugs me ), but I guess that's what the Boundary Constraints are for. Unfortunately I cannot get them to work. I chose G1 or G2, but the CVs stay put... :/ I also get no CV movement out of the edge symmetry tool...?

1. What am I doing wrong? (maybe a link to a tutorial? )
2. What are the other tools?

I hope someone can follow my chain of thought...

3 REPLIES

# Re: CV (Knot) Snap in X Form

Phenom
Can't really help with accomplishing the symmetry & continuity issues or best ways to pull & tug knots/poles, but there is a Grid in NX it's just turned off and you need to turn it on.

Look in the NX Documentation under Fundamentals -> Customizing the NX Environment -> Using Preferences -> Grid
-Tim

# Re: CV (Knot) Snap in X Form

Siemens Phenom

If you do not have one already then create a Datu, Cooedinate System on your symetry plane.

Then use the Edge Synnetry command.

Steve V

# Re: CV (Knot) Snap in X Form

Siemens Phenom

Hi,

You can try this option also.

Snip the patch (using snip) by the symmetry plane.

Extrude the edge on the symmetry plane (direction normal to the plane) to get a sheet.

Use MATCH EDGE (G1 only) to get the desired tangential symmetry.

I think as Steve suggested "Edge Symmetry" should also work.

Best Regards

Kapil