When working with parts in nTop, sometimes you may need to increase or decrease the size of the part. There are two main options for doing this: Thicken Body and Offset Body.
Thicken Body: Create a thickened hollow Implicit Body using an Implicit boundary as a mid-surface.
The Thicken Body block will thicken the part in both directions, using the boundary of the body as the centerline of the thickness. Thicken Body is best to use for 1D or 2D parts, such as CAD surfaces or graph lattices. When thickening a lattice, the thickness value can be thought of as a diameter value.
Offset Body: Offset the surface boundary of an Implicit Body inward or outward.
Offset Body works best for objects that already have a volume. It will adjust the surface boundary of the part. A positive value will increase the surface boundary, while a negative value will decrease it. When offsetting a lattice, the distance value can be thought of as a radius value.
Usage in Lattices and Surfaces: Thicken Body Recommended
When an Offset Body is used for a graph lattice, the Offset occurs in every direction since the graph lattice boundary is 2D, which doubles the thickness value. Watch the gif below to see the difference between Thicken Body and Offset Body of the same thickness value on a graph lattice. The Thicken Body creates a total thickness of 1 mm for the lattice, while the Offset Body creates a total thickness of 2 mm. The negative thickness and offset values will result in no volume since a surface or graph lattice cannot decrease in volume.
Usage in Volumes: Offset Body Recommended
Since Thicken Body uses the boundary as a midpoint, it is recommended to use Offset Body when you are starting with a part that already has volume. In the gif below, Thicken Body only adds 0.5 mm to the outside of the body, and Offset Body moves the boundary of the body out by the full 1 mm.