Trouble creating perforated curved 3d polygons

[ChrisW]

How would I go about creating curved perforated walls in VW (see example below)? Creating straight perforated walls is easy enough but I am unable to edit the wall curvature after I've used the subtract solids tool. These shapes were created in formz using the bend-curve tool then applying a thickness to the surface. Does VW have an equivalent tool or is there another way of approaching this?

Thanks,

Chris

[Benson Shaw]

If you just want to look at it, create a curved wall or extrude or something, create a flat texture of the graphic, and apply the texture to the solid. Edges may be transparent, so not a perfect solution.

Here is one way if you are modeling:

1. Create an extrude of a curved line (say in plan view) for the front surface of your wall.

2. Switch to front view, and create a bunch of 2d objects which will be your punches. 3. Convert all objects to NURBS (ungroup if you did a batch conversion). Wall should be a NURBS surface, punches should be NURBS curves.

4. Switch to plan view.

5. Rotate your punch objects if necessary, so they are prox parallel to the wall.

6. Use the Project Tool in Project & Trim mode to punch through the wall - 3 clicks for each punch. Refine the punch direction if that's a concern by setting the working plane parallel to each punch.

7. Apply the Shell Tool to give your punched NURBS surface some thickness.

There are other ways, too, with solid intersection, etc

-B

[michaelk]

I agree w/ Benson that the shell tool is crucial.

Here's another way to approach it:

1. Draw the 2d shape. (Clip and add surfaces or draw individual polylines and use the paint bucket mode on the polygon tool.)

2. Switch to a front view. (make sure the polyline is in screen plane mode)

This part is a little weird. But it's a great short cut:

3. Select the polyline. Model>Extrude (extrude 0") then Modify>Convert>Convert to Nurbs. It's a quick way to get to a nurbs surface. (There's a probably a more kosher way to do this, but I like it because be done w/ just keyboard shortcuts.)

4. Switch to an isometric view.

5. Double click the nurbs surface. (3D reshape tool becomes active) Select the "Move U Vertices Mode" and "Y Axis Constrain Mode". In the OIP set Move: to U Vertices. In the U Degree field enter 2 (or more - the higher the number, the more complicated you can make the curve).

6. Use the left arrow, right arrow, and middle buttons (labeled "Edit U" and "Edit V" in the OIP) to navigate to one of the center vertices.

7. Make sure the Weight field is "1". Enter a value in the Y field that is twice as much as you want the curve to be. Or just grab a vertex and drag.

8. Use the shell tool to set a thickness...

The middle steps are a little convoluted, but creating the curve of the shape as a nurbs surface after mapping the profile as 2D geometry gives you a lot more control over the perforations and over the final shape of the curve - and it keeps the angle of the cutouts perpendicular to the face.

I'll attach an example...

michaelk

[Benson Shaw]

Good one, Michaelk!

I'm not sure what happens in FormZ, but both these VW methods end up fudging the perforation shapes compared to real world fabrication. Imagine manipulating a flat metal sheet. Cut a circular hole in it and then bow the sheet. The bent circle is now taller than it is wide (straight line measurement - the length of the bow string).

In Michaelk's method the wall gets longer, and circle width is stretched rather than compressed when the NURBS points are pulled off the plane. Maybe to correct that, one could start with the flat rectangle at correct curved wall length, make the perforations, convert to NURBS, pull the middle out to bow it, and move the ends inward to shorten the new bowed wall length back to the flat length.

In my method, the circular hole is distorted in different ways depending on the direction & shape of the punch.

Oh well. CAD is a virtual approximation/description of the design, and fab/construction is a methods and materials approximation of the design.

-B

[ChrisW]

Great! This works perfectly. Thanks for the responses.