to display a dialog box that you can use to chop away part of the triangle mesh. Click on the Slice Triangles button to display a dialog box that you can use to chop away part of the triangle mesh.
You use the Plane Normal area to specify the direction of the slicing plane's normal. This plane must be perpendicular to either the X, Y or Z axis.
You define the plane's position using the Position along axis box. If you prefer, you can pick this position in the Graphics window. The plane is marked on the model as a yellow line.
The triangle mesh to one side of the plane will be discarded. You can select to keep either the Lower or Upper part of the triangle mesh in the Part of model to be kept area.
In order to see the part of the model that will be kept, you must have the triangles displayed in the Graphics window. If the triangles are not shown, click on the Draw Triangles button 
to display them.
