By adding tangency conditions you can pull the surface of the loft in the direction of the tangent. For part lofting you add the part related tangent conditions within the Loft to Part specification.
Unless you switch AutoWeight on, tangency conditions are always valid for the complete profile, workplane, or face. With AutoWeight on, Creo Elements/Direct Modeling tries to optimize the tangent conditions and applies a varying tangent weight for all specified tangents. The tangent directions do not vary.
To add a tangent for a part loft between two parts,
1. Create the two parts.
2. Click Modeling and then, in the Model group, click More.
3. Click To Part in Basic Loft section. The Loft to Part and Select dialog boxes open.
4. Click Part and specify the part to create or add material to.
5. Click Type and choose Part/Part.
6. Click Edges1 and select the edges on the first part.
7. Click the option menu next Tangents1. The option menu offers three choices:
a. No Tang to proceed without a tangent condition.
b. To Faces to add tangent conditions to the faces.
a. Click To Faces. The Define Tangent menu is displayed, and on the part a turquoise line appears to indicate the tangent direction. The default tangent direction is parallel (0 degree) to the adjacent neighbor faces.
b. Click Angle and enter the angle for the tangent. The angle is measured relative to the neighbor face.
c. Click Weight and enter a weight (between 0.2 and 5 - the greater the number, the stronger the pull of the tangent).
d. Click Adjacent on or off to toggle the tangent between the two adjacent faces.
e. Click Apply to add the tangent without ending the operation.
c. User Def to add user defined tangent conditions.
a. Click User Def. The Define Tangent menu appears with the All option on.
b. To define tangents for all vertices belonging to the highlighted set of edges:
a. Click Direction and use the options in the Direction 3D menu.
b. Click Weight and enter a weight (between 0.2 and 5 - the greater the number, the stronger the pull of the tangent).
c. To modify single vertex tangents:
a. Click Single.
b. Click a vertex with a tangent.
c. Click Direction and use the options in the Direction 3D menu to specify a new direction for the tangent at this vertex.
d. Click Weight and enter a weight for the tangent.
e. Click another vertex. The vertex tangent gets the same tangent conditions as the previous vertex tangent. To give new tangent conditions proceed as above.
d. To modify all vertex tangents of the set:
a. Click All and specify a new direction and weight for all vertex tangents.
e. Click Apply to add the tangent definition without ending the operation.