Move Nurbs vertex parallel to working plane

[Benson Shaw]

I am trying to draw a piece of sheet metal which is then curved into an arc. The outline of the metal is a wavy oval.

To simplify, draw a nurbs circle in Front view.

Pull the handles with 3d reshape too to create wavy outline. So far all points are co-planar.

Reset view to plan view. Now you see a line with some individual verticies, and some "stacks" of verticies/handles.

The task is to move the middle bunch of points in this view, so that they stay the same height from the working plane.

If I move them with the 3d reshape tool they move sideways as directed, but also revert to the working plane. I can use the x axis mode and the y axis mode, but that means two moves for each point - cumbersome for more complex shapes. I can also use the OIP to define a new coordinate for each point. I thought Shift MoveClick might constrain them to stay in their plane, but no such luck. This should be simple. What am I missing?

VW12.0.1

Mac 10.4.6

-B

[NickB]

Hi Benson,

I'm not sure I've entirely understood what you're trying to do, but here are a couple of thoughts that may help if I've got it right.

Draw the circle in plan view, pull the handles around, switch to an isometric view, and then use the 3D reshape tool constrained to the z axis to make the curve, finally rotate the object so that it is 'standing-up'.

Another approach that may be neater would be to draw a rectangular NURBS Surface (again in plan view), curve that into an arc (fewer vertices and clearly arranged), and then in plan view draw your outline curve and Project and Trim the curve onto the surface. Finally rotate it.

Hope that's what you were looking for. Nick.

[islandmon]

Use the 2dPoly Reshape (XY) in any view whatsoever and the Z coordinate will never be changed. The 3dPoly Reshape Tool resets the Z value to '0' as soon as you move the handle.

[Benson Shaw]

Thanks, Nick & IslandMon - Sorry to let this languish so long - busy couple of weeks.

My proposed method results in a sort of domed surface, like a potato chip or saddle, rather than the desired equivalent of a rolled piece of sheet metal. I have also used solid intersection of two extrusions - one for bent sheet and the other sort of a punch through it. Unfortunately, this method yields tons of verticies on the resulting object.

A hybrid of Nick's solution works best for me - Vertices of the nurbs rectangle can be moved to form arc w/ 3d reshape tool (constrained) in the edge view. Trimed/Projected surface has same, small vertex count as projecting object. Notes: In isometric view, it's difficult to move the verticies same distance from plane, so I did moves in edge view. Edge view of rectangle can be precisely shaped to more complex curves if u/v degree is higher than 2.

IslandMon's did not work for me. Vertices of 3d polys and nurbs curves and surfaces do not respond to 2d reshape tool. Or is there a way to make that work?

Nurbs are desirable because number of verticies remains small. A file with lots of verticies (I'm working on a huge and complex terrain with building massing models, pathways, railings, hardscapes and lots of sheet metal sculpture) can take up lots of time to render, pdf print and paper print.

Anyway, please forgive late reply and thanks again.

-B

[islandmon]

3dPoly>Convert to Mesh>enter group ... then use the 2dPoly reshape ( very helpful when the Z value needs to be retained ).

Unfortunately, 2dPoly Reshape does not work with NURBS.