Alibre Design

Chapter 7 - Feature Creation5. If Specify Tangent is checked, Tangent Angles can be specified for sketches (butnot faces). Specify the desired angle in the Tangent Angle field. In this case, thelofted surface tangent would be at the angle specified with the sketch planenormal.6. If Specify Tangent is checked, additional control is obtained using the TangentMagnitude for each Cross Section. Tangent Magnitudes control the rate at whichsurfaces diverge from the cross section sketch planes or faces. As TangentMagnitudes increase, surfaces diverge more slowly from surface tangents at thesketch cross sections. Specify the desired value in the Tangent Magnitude field.A value of 0 is equivalent to not using “Specify Tangent”.7. If desired, Guide curves can be specified to constrain the location or direction ofthe lofted surface that is generated. To specify Guide curves, check the GuideCurves checkbox, and select the sketches in the work area. 2D and 3D sketchesmay be used.Guide curves are each exactly one open or closed loop, each touching all theprofiles. Multiple guide curves can be used for Global and Local types,however, for the Tangent type, only one guide curve should be specified. Aseach curve is selected, the corresponding labels appear in the Guide Curveslist box. To remove a Guide curve from the box, select it from the list andpress delete key on the keyboard, or choose an option from the right-clickmenu.Guide curve types:Global: Creates “virtual” guide curves, providing the ability to make one guidecurve globally affect the lofted surfaces.Local: These guide curves provide the ability to make one guide curve locallyaffect the lofted surfaces.Tangent: Constrains the take-off vectors on each profile based on a “path”curve. The resulting surface does not follow the path; rather aconstant vector field is placed on each profile. The vector is defined as thetangent vector of the path curve at the point in which the curve intersects theprofile's plane.8. If necessary, select a loft creation option:• Simplify Surface: Converts the resultant loft face from a spline type toan analytic type when possible. A simplified surface contains less data, isof higher quality, and is faster to process in subsequent modelingoperations.• Minimize twist: Aligns the profiles so that the start of the second sketchis aligned to the start of the first sketch.170