About the Extend Feature
Use the Extend tool to extend a quilt. You do this by selecting a boundary edge chain on the quilt to be extended. To activate the Extend tool, click > 
Extend.
Extend.You can extend a quilt either by a specified distance, or up to a plane:
• 
Along Original Surface—Extends the surface boundary edge chain along the original surface.
Along Original Surface—Extends the surface boundary edge chain along the original surface.• 
Up to Plane—Extends the boundary edge chain up to a specified plane in the direction normal to this plane.
Up to Plane—Extends the boundary edge chain up to a specified plane in the direction normal to this plane.When Along Original Surface is used to create an Extend feature, choose one of the following options to determine how the extension is done:
Along Original Surface is used to create an Extend feature, choose one of the following options to determine how the extension is done:• Same—(Default) Creates the extension of the same type as the original surface (for example, plane, cylinder, cone, or spline surface). The original surface is extended past its selected boundary edge chain.
• Tangent—Creates the extension as a ruled surface that is tangent to the original surface.
• Approximate—Creates the extension as a boundary blend between the boundary edges of the original surface and the edges of the extension. This method is useful when extending the surface up to a vertex that does not lie along a straight edge.
When extending quilts, consider the following information:
• You can indicate whether you want to measure the extension distance along the extended surface or along a selected datum plane.
• You can add measurement points to the selected edge so you can vary the extension distance at different points along the boundary edge.
• You can enter a positive or negative value for extension distance. If the configuration option show_dim_sign is set to no, entering a negative value flips the extension direction. Otherwise, entering a negative value sets the extension direction pointing to the inner side of the boundary edge chain.
• Entering a negative value causes a surface to be trimmed.