To Align Surfaces
1. Select a free form surface that you want to align with another free form surface.
2. Click > 
Align. The Align tab opens. An edge of the surface is highlighted. This edge of the surface is aligned and modified.
Align. The Align tab opens. An edge of the surface is highlighted. This edge of the surface is aligned and modified.3. Select Position, Tangent, Curvature, or Normal constraint on the Align tab. Position is the default.
4. Click the Side 1 collector on the Surface Sides tab.
5. Select an edge of another surface as reference.
While aligning, the surface that you selected modifies itself to align with the selected reference and the selected constraint is applied.
6. If required, move the edge of the modified surface along the reference to the required location. The edge of the modified surface is indicated by a handle.
7. If required, you can also align the other edges of the surface. Click Side 2, Side 3, or Side 4 on the Surface Sides tab and repeat steps 5 and 6.
8. If required, change the applied constraint using the Surface Sides tab. Select a new constraint from the list next to the Side 1, Side 2, Side 3, or Side 4 collector on the Surface Sides tab to apply the constraint to Side 1, Side 2, Side3, or Side4 of the selected free form surface, respectively.
9. Click 
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