About Tangent Draft
Tangent Draft features can add or remove material tangent to the selected surfaces of a reference part on one or both sides of a parting surface. Tangent drafts can be created as either solid or surface features. You can also create neutral curves based on the tangent draft geometry. You may need to create a parting surface and a reference curve, such as a draft line, prior to using the Tangent Draft functionality.
The types of tangent drafts are:
• Curve-driven tangent draft—Adds material on one or both sides of a parting surface between a reference curve (such as parting curve or sketched curve) and selected surfaces of the reference part, tangent to these surfaces. The reference curve must lie outside of the reference part.
• Constant-angle tangent draft—Adds material by following the trajectory of the reference curve and creating surfaces at a specified constant angle to the Pull Direction. Use this feature to add draft to surfaces that cannot be drafted with the regular Draft feature. You can also use this feature if you need to add drafts to a rib with rounded edges and preserve tangency to the reference part.
• Tangent draft cut—Removes material on one or both sides of a reference curve (such as draft curve or silhouette curve) at a specified angle to the reference part surfaces and provides a rounded transition between the draft surfaces and the adjacent surfaces of the reference part.
When you create a tangent draft, you select the draft type, geometry, and side options, and specify the Pull Direction. If a Pull Direction has already been defined in the mold or cast model, you can either accept the default direction or specify a different one. Then you select a reference curve and define other draft references, such as tangent surfaces or draft angle and radius, depending on the tangent draft type.
The optional elements of a tangent draft are:
• Spine Curves—Lets you specify an additional curve that controls the orientation of normals to the sectioning plane. Use this element if using the reference curve alone results in geometry intersecting itself.
• Closing Surfaces—Lets you trim (or, in some cases, extend) the tangent draft up to selected surfaces. Use this element when adjacent surfaces are located at an angle to the surface being drafted.
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A closing surface must always be a solid surface. A datum plane or a surface geometry cannot be a closing surface.
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• Cap Angle—For one-sided curve-driven tangent drafts, controls the draft angle for additional planes created automatically when a draft line does not extend to the surface borders and the Closing Surfaces have not been specified. If no value is specified, a zero angle is used.
Finally, you can edit the reference curve by using the Curves tabbed page. Select the reference curve segments to include in draft line or exclude from draft line. Use this functionality when the system has trouble creating the tangent draft, for example, when the reference curve intersects itself.