Getting uniform thickness after two blends

[blam-jam-man]

I've created a hollow shape, first by blending from a square with rounded corners to a circle, then by using a second blend concentric to the first but slightly smaller and removing material. The issue is that the resulting structure does not have a uniform thickness. Is there a way to make the thickness uniform?

[tbraxton · Accepted solution]

The shell feature is useful for some geometries and can be used on solid geometry and is easier and preferred to building surface models when it can be used. It may work if you get to a solid defined by the first blend shape.

The arguably more robust approach to maintaining wall thickness of non trivial forms to model the surfaces explicitly. For your specific example:

Use the surface option for the first blend feature. Offset (normal to surf) this feature by the desired wall thickness. This only works if the geometry supports a constant wall thickness otherwise you will have to tweak the first blend to enable the offset. It may not be easy to control the topology of the blend to manipulate it to enable the offset.

In the context of what most would consider complex shapes (styled surfaces that need to be molded) but would also apply to engineered surfaces such as optical or fluid handling (e.g. turbo charger volute).

A best practice for geometry with a controlled wall thickness is to build it with surfaces (usually outer surface) and then offset it by the desired wall thickness. When doing this check your offset often to insure that all underlying surfaces can be offset by the design goal.

[blam-jam-man]

Looks like the shell was the way to go. Thanks.

Doing surfaces can cause issues like attached where things don't line up evenly.