# How to create a 3D tri-axial ellipsoid in Alibre Design

*Example file for this tutorial is attached below

Here is an example of a 3D Tri-Axial Ellipsoid. Notice the above is an ellipsoid shape, with three distinct axises of symmetry, a, b, and c.

If you revolve a simple sketch created using the "ellipse" sketch tool with height & width a and b, and revolve about axis a, you run into a problem: You only end up with a 3D Bi-Axial ellipsoid, such as the one shown below with axises a and b. To make an ellipsoid tri-axial we can't rely on only sketch revolve.

Let's assume we have the above bi-axial ellipsoid with width which corresponds to the desired tri-axial ellipsoid dimension of b. But, we also need an axis of length to be present in our ellipsoid.

Since is of known length, as is c, it's possible to assume there exists some S value you can solve for, such that:

S*c = b

After solving for S, here we use Alibre Design's non-uniform scale command on the bi-axial ellipsoid to modify the c direction with scalar value = S.

The result after the scaling is a tri-axial ellipsoid:  Did you find it helpful? Yes No

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