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Lofting Options Explained

Lofting sketches can quickly and easily generate non-prismatic parts. When values are entered for a combination of the three Cross Sections options it can give you radically different parts. These options give you more control over how your part looks.

Specify Tangent enables the Tangent Magnitude and Tangent Angle options.

Tangent Magnitude controls the rate at which surfaces diverge from the cross section sketch planes or faces. As Tangent Magnitudes increase, surfaces diverge more slowly from surface tangents at the sketch cross sections.

Tangent Angle allows you to specify the angle of tangency for the specified for sketches (but not faces).

Tangent Angle

The easiest way to see what the different options are is to see them in action. The loft in Fig 01 was created by sketching a 3.0" circle on the XY plane and creating an offset plane 1.00” from the XY plane. The only sketch entity on the new plane is a Sketch Node that was placed at the origin. The circle and point were then lofted together and no cross sections options were used (Fig 02).

By selecting Specify Tangent and changing the value of the Tangent Angle to 90 in the Point Sketch, you can see that the model in Fig 03 is different than the original. The value of 90 for the Point Sketch (Fig 04) essentially makes the original sharp point into a spherical shape.

Entering values for other sketches demonstrates how the part can also be drastically changed, Fig 05 and Fig 06. In this example a value of -90 was used for the Circle Sketch and that sketch is mushroomed out at the bottom because the loft is coming off the circle at -90o and then lofts to the point. By using a value of 90 for the Circle Sketch's Tangent Angle value, you can achieve the shape in Fig 07.

Tangent Magnitude

Changing the Tangent Magnitude changes the rate at which the loft deviates. The values you use can vary significantly depending upon the sketches your are using, but a smaller value causes a faster deviation and a larger value causes a slower deviation. With the previous model, change the Tangent Angle for the Circle Sketch to 60.0 (Fig 08 and Fig 09). We will now change the Tangent Magnitude values and see how the model changes (Fig 10 and Fig 11).