How to make solids "solid"?

[RonR]

This is probably very basic, but I'll ask anyway. When drawing solid shapes- mechanical parts, in my case, I often want to create a cutaway view. But my parts, when split, often appear to be shells rather than solids. That is to say the sectioning surface doesn't create a flat surface on the part, and if I split an object in half, what I see is the interior of the skin, rather than the sectioned surface.

What am I doing to cause this to happen?

Thanks, RonR

[Peter van der Elst]

I think this is just how it works. The command makes a section of the faces. Maybe it's something for the wishlist. You could close them with the 3dpolygon tool (I think...). If you then group those polygons you can give them a nice reddish (or something) color. (just an idea)

[propstuff]

It depends on the type of solid and what you cut it with.

If you start with a simple solid, solid extrude, or a mesh object, and cut it with the Split by Line tool you will end up with a new solid.

If you cut it with the Cut 3D Section tool you will end up with a hollow cut what ever it was you started with.

You can (usually) fill in the cut end by using the Extract Curves and/or Create Planar Caps tools. It depends a bit what type of object was cut.

cheers,

N

[tom kyler_dup1]

Ron, you probably won't like this answer. If you begin with a solid, and then use the "cut 3D section" you'll end up with a "group" of 3D polygons with an open side where you cut. You have to "ungroup", then "add solids", then "convert to nurbs", then "ungroup" again, then "add solids" again, then "create planar caps" and finally "add solids" a last time. and that will turn your hollow model into a solid and cover up that open side, at least for most geometry

Fun huh? This has to do with the way Vectorworks keeps track of an objects creation history. By ungrouping and using the "add solids" command, you essentially loose some ability to go back and change parameters you used to create your part initially. But since the "3D section" creates a copy of the section, then this isn't usually a problem.

If you use the "cut line" you'll cut your model, but will still be able to go back and edit it. If you go this route, then you won't be able to cut multiple sections without making copies of your model.

The mathematical model a computer uses to classify something as a solid, nurbs surface, or polygon is different, and each time you do that "ungroup" and "add solids" you're essentially converting your model from one type to another finally getting to a type (nurbs in this case) where you have the ability to cover up that "hole" (with the "add planar caps" command). It's a "by-product" of the method Vectorworks chooses for their design process and still be economically viable.

[ 05-06-2004, 10:39 AM: Message edited by: tom kyler ]