Edge Blend

Edge Blend

Use the Edge Blend command to round sharp edges between faces.

You can do the following:

• Add a single edge blend feature to multiple edges.
• Add corner setback points to change the shape of an edge blend corner.
• Adjust the distances of the corner setback points from the corner vertex. You can use corner setbacks to create ball nose blends, for example, and as an aid in sheet metal stamping of non-styled surfaces.
• Create a blend with a Circular or Conic shape.
• Add stop short points to end an edge blend short of a specific point.
• Create an edge blend of constant or variable radius.

It is a good practice to do the following:

• Add blends last, except when they provide a face or edge that you must have to complete your design.
• When you edit a series of blends, edit them in order of their timestamps, because blends frequently modify edges created by earlier blends.

Where do I find it?

Application	Modeling
Command	Edge Blend
Graphics window	Right-click an edge→Blend

Create a circular edge blend with constant radius

1. Choose Home tab→Base group→Edge Blend .
2. In the Edge group, from the Continuity list, select G1 (Tangent).

Select Edge is active. 3. In the graphics window, select edges for the first edge set.

For this example, two edge strings are selected.

Handles are displayed on the selected edges.

Tip: It is recommended that you blend sets of edges at the same time, rather than blending edges one at a time. 4. From the Shape list, select Circular. 5. In the Radius 1 box, type a value to specify the radius of the first edge set.

For this example, the radius of the first edge set is set to 15. 6. Click Add New Set to complete the selection of the first edge set.

Select Edge is active. 7. In the graphics window, select more edges for the second edge set.

Handles are displayed on the selected edges. 8. In the Radius 2 box, type a value to specify the radius of the second edge set.

For this example, it is set to 20. 9. Click OK to create the edge blend feature.

Create a conic edge blend

Choose Home tab→Base group→Edge Blend .

In the Edge group, from the Continuity list, select G1 (Tangent).

Select a set of edges for the first edge set.

In the Edge group, perform the following actions:

1. From the Shape list select Conic.
2. From the Conic Method list select Boundary and Center.
3. In the Boundary Radius 1 box, type 3.
4. In the Center Radius 1 box, type 2.
5. Click Add New Set .

Select a second set of edges for the next edge set.

Perform the same actions on the second edge set that you performed on the fist.

Click OK.

Create an edge blend of variable radius

This example shows how to create a blend with varying radius by defining points along the edge at which you want to vary the radius of the blend.

1. Choose Home tab→Base group→Edge Blend .
2. In the Edge group, from the Continuity list, select G1 (Tangent).

Select Edge is active. 3. Select edges for the edge set.

For this example, three edges are selected for the edge set. 4. From the Shape list, select Circular. 5. In the Radius 1 box, type a value to specify the radius

For this example, it is set to 10. 6. In the Variable Radius group, click Specify Radius Point. 7. Click Inferred Point and specify points on the edges where you want to set a variable radius value.

For this example, two variable radius points are selected on a vertical edge. 8. To specify variable radius values, in the Variable Radius group, do the following:

Click List.

The list shows the two selected variable radius points, V Radius 1 and V Radius 2. 9. Select V Radius 1 and in the V Radius 1 box, type a value.

For this example, it is set to 15. 10. Select V Radius 2 and in the V Radius 2 box, type a value.

For this example, it is set to 25.

Move the location of a variable radius point by choosing a Location option: %Arc Length, Arc Length, or Through Point.

For this example, %Arc Length for V Radius 2 is set to 45.

If you manually move the point location by changing the value for % Arc Length, the point loses its associativity.

Click OK to create the blend feature with variable radius points.

Add setback points to an edge blend corner

This example shows how to change the curvature of the corner when you blend three or more edges.

1. Choose Home tab→Base group→Edge Blend .
2. In the Edge group, from the Continuity list, select G1 (Tangent).

Select Edge is active. 3. Select three edges that intersect at a corner for the edge set.

Handles are displayed on the selected edge set. 4. From the Shape list, select Circular. 5. In the Corner Setback group, do the following:

Click Select End Point. 6. Select the vertex point of the blend corner that has three edges.

A corner setback with default values is displayed at the vertex, and is aligned along the three edges. 7. Click List to display the setback points. 8. Select each setback point from the list and change the value in the Point Setback box.

For this example, Point 2 Setback 1, Point 2 Setback 2, and Point 2 Setback 3 are changed to 15, 20, and 25, respectively.

The new setback distances change the shape of the corner.

Click OK to create the blend with setback corners.

Stop an edge blend short of a corner

1. Choose Home tab→Base group→Edge Blend .
2. In the Edge group, from the Continuity list, select G1 (Tangent).

Select Edge is active. 3. In the graphics window, select edges for the first edge set.

For this example, one edge string is selected. 4. From the Shape list, select Circular. 5. In the Radius 1 box, type a value to specify the radius of the first edge set.

For this example, the radius of the first edge set is set to 10. 6. In the Stop Short of Corner group, do the following:

From the Limit list, select Distance. 7. Click Select End Point and select end points on the edge set where you want to stop the blend.

The Location and Arc Length options appear.

Handles are displayed at the selected end points. 8. In the Location list, select Arc Length. 9. Click List to display the list of stop short points. 10. Select Stopshort1 and type a value in the Arc Length box.

For this example, it is set to 10. 11. Select Stopshort2 and type a value in the Arc Length box.

For this example, it is set to 30.

The stop short points are moved to the specified distances.

Click OK to create the blend.

Create an edge blend with curvature continuity

This example shows how to create edge blends that are curvature continuous (G2) with their adjacent faces.

1. Choose Home tab→Base group→Edge Blend .
2. In the Edge group, from the Continuity list, select G2 (Curvature).
3. With Select Edge active, select the edge(s).
4. Set the desired radius and rho.

For this example, a radius of 8 was used. 5. Click OK.

Edge Blend dialog box

Edge
Continuity
Select Edge
Shape
Radius x
Conic Method
Boundary Radius x
Center Radius x
Rho x
Variable Radius
Creates a variable radius blend by adding points with unique radius values to the edge chain. Note: If you define variable radius points on the chain of edges, it is good practice to also define them at both end points of the chain. Otherwise, NX will define its own variable radius values at the chain end points based on where the other variable radius points have been defined. Example: Single variable radius When a single variable radius is defined at a point on the left segment of a two-edge chain: The left chain segment end point defaults to the radius value defined on that segment. The right chain segment end point radius defaults to the value in the Radius 1 box. If there is more than one variable radius defined on the left segment, then the end point gets the value of the one nearest to it.
Two variable radius When two variable radius points are defined, one on each segment of a two-edge chain: The radius at the left end point of the chain defaults to the value of the variable radius defined on that segment, The radius at the right end of the chain defaults to the value of the variable radius defined on that segment.

Specify Radius Point

Available when you select an edge using Select Edge in the Edge group.

Lets you specify radius points and set radius values along edges in an edge set.

• You can define a variable radius point location that is not on the blend edge. NX automatically projects it to the edge.
• Variable radius points are associative. If you move the associated point when the part is updated, the variable radius location moves with it. If you delete the point, the variable radius location for that point continues to exist (as a percent of arc length), but is no longer associative.

V Radius xx

Available when you select a variable radius point.

Sets the radius at the selected point.

xx is the number representing the variable radius point.

You can change the radius values in the graphics window.

Variable radius points with drag handles

Location

Available when you select a variable radius point.

Lets you specify one of the following options to position the variable radius point on the edge.

Sets the specified value for the arc length.

Enter the distance values in the Arc Length box.

Sets variable radius point as a percent of total edge arc length.

Enter the distance values in the % Arc Length box.

Lets you specify a variable radius point.

Specify Radius Point options are available.

You can also do the following:

• Drag the variable radius point handle along the edge.
• Type values in the scene dialog.

If you manually move the point location by changing the value for % Arc Length, the point loses its associativity.

Right-click a point handle to toggle between Arc Length and % Arc Length.

Soft Radius Change at End

Select this option to apply a soft change at the end of the blended chain. Zero slope at each end of the blended edge chain.

Corner Setback

Select End Point

Appears when Continuity = G1 (Tangent).

Lets you select an end point to specify setback along each edge entering the corner. A drag handle displays at each edge.

Use the drag handles to increase the corner radius values as required.

Do not use this option for creating curvature continuous faces.

Point 1 Setback 1

Lets you set the distance for the currently selected setback point to the value you specify.

The option Point 1 Setback 1 corresponds to the first point set and the first set back. The number varies according to the point set and the edge you select.

Corner Setback

Appears when Continuity = G1 (Tangent).

Specifies whether setbacks are included in the edge blend corner or if they are kept separate.

Include with Corner		Separate from Corner

Stop Short of Corner

Stops an edge blend at a point short of the end of the edge.

Select End Point

Lets you select a end point to limit the length of the blend.

After you select the edge end point, you can specify the Limit.

Limit list

Available when you select an end point.

• Distance stops the blend short of the edge end point.

** Stop Short of Corner using Distance

**

• Blend Intersection stops a blend at the selected vertex where multiple blends intersect.

You cannot use Distance at an end point where edge blends intersect.

Use Blend Intersection to create multiple edge blends at a complex vertex, where the default resolution is likely to fail, so that blend-to-blend intersections can be resolved using a manually created patch.

Location list

Available when you select an end point in the Select End Point group.

• Arc Length lets you specify a value for arc length at which you want to select a stop point.
• % Arc Length lets you specify the percentage of the arc length at which you want to select a stop point.
• Through Point lets you select a point on the model.

Specify Point options are available.

Limit Length

Trims an edge blend to a selected face or plane.

Before and after trimming

Enable Length Limit

When selected, the following options let you specify objects and locations to use to trim blend faces.

Limit Object

Lists methods for trimming the edge blend with specified objects.

The limiting plane, face, or edge set (or its extensions) becomes the end cap for the blend.

Trims the edge blend with one or more planes in face sets.

Specify Plane

Lets you specify planes to trim the blend.

Trims the edge blend with one or more faces in face sets

Select Face

Lets you specify faces to trim the blend.

Trims the edge blend with one or more edges in edge sets.

Select Edge

Lets you specify edges to trim the blend.

Trim to Limit Object

Trims blend length to the limit object, otherwise limit length to the first intersection point.

Use Limit Plane to Cap Blend / Use Limit Face to Cap Blend

Available when Trim Object = Plane or Face.

Caps the blend using a plane or face.

Specify Point options are available.

Specify a point nearest to the intersection where you want the blend capped. Use this method if the trim plane intersects the blend face in more than one location.

Specify Trim Location Point

Available when Limit Object = Plane.

Specifies a point nearest to the intersection where you want the blend capped. Use this method if the trim plane intersects the blend face in more than one location.

Overflow

Controls how blend overflows are handled. Blend overflow occurs when tangent edges of a blend encounter other edges on the solid.

Preferences

Roll Across Smooth Edge

Rolls across a smooth edge, when the blend encounters a smooth edge.

Roll Along Edge

Appears when Continuity = G1 (Tangent).

Rolls along an edge, when the blend encounters a smooth or sharp edge

Trim Blend

Appears when Continuity = G1 (Tangent).

Extends the neighbor face to trim the blend, when the blend encounters a sharp edge.

Explicit

Controls whether the Roll Along Edge overflow option is applied to a selected edge.

Available when Continuity = G1 (Tangent).

Select Edge to Force Roll on

Lets you select an edge on which you want to force the Roll On Edges (Smooth or Sharp) option.

Select Edge to Prohibit Roll on

Lets you select an edge on which you do not want to apply the Roll On Edges (Smooth or Sharp) option.

For this edge blend, an encountered edge is selected with Select Edge to Prohibit Roll on option. This will prevent the Roll On Edges (Smooth or Sharp) option being applied to it. The Roll On Edges (Smooth or Sharp) option is applied to the edge of the other cylinder as usual.

Overlap

Preference list

Specifies how overlapping blends are resolved.

This option differs from those with **Overflow ** in that it only affects the interaction of edges within a single edge blend feature. **Overflow ** can be effective for any edge, including blend edges.

• Trim Blends trims overlapping blends to each other, when overlapping blends of same convexity are applied at the same time.
• If Different Convexity, Roll Over makes the blend roll over itself. Use this option to roll the blend over itself when the convexity is different as the blend encounters a portion of itself.
• Roll Over Blends rolls over region of overlap, when overlapping blends of same convexity are applied at the same time.

Blend Order list

Specifies the order in which blends are created.

It is recommended that you try this option to create blends in situations where they would otherwise fail.

• Convex First applies convex blend first. Concave blend rolls over convex when overlapping blends of opposite convexity are applied at the same time.
• Concave First applies concave blend first. Convex blend rolls over concave when overlapping blends of opposite convexity are applied at the same time.

Settings

Patch Mixed-Convexity Corner

Appears when Continuity = G1 (Tangent).

Patches corner when blends of opposite convexity are applied at the same time.

Use this option to get a different shape for blends that meet the following criteria:

• The blends are of opposite convexity.
• The blends meet at three or more edge vertices.
• One blend rolls over the other.

Remove Self-intersections

Replaces intersections of the blend with itself with a smooth surface patch.

The patch area is not a true representation of a blend produced by a rolling ball, but it is tangential to all the surfaces with which it connects.

This solution may allow an otherwise self-intersecting blend to be created but it may be costly to produce the patched surface.

If you have not selected Remove Surface Self-Intersections option, make sure that the offsets of the surfaces attached to the faces meeting at the edge to be blended do not self intersect. These offsets of the surfaces attached to the faces must intersect to define a "spine" curve for the blend.

Patch Areas of Complex Geometry

Examines selected blend edges for areas of possible failure due to tight curvature or complex topology. If areas are detected that will fail, partial blends of limited data are created and patches automatically created between them. This option relieves users from having to manually create small blend segments and bridging patches in order to blend a complex area that would not normally support an edge blend.

See also the Limit Blend to Avoid Failure Areas option.

Limit Blend to Avoid Failure Areas

When selected, blends are limited to avoid areas that cannot be blended, with or without patching, depending on the setting of this option and the Patch Areas of Complex Geometry option.

Patch Areas of Complex Geometry	Limit Blend to Avoid Failure Areas	Behavior
		Areas that can be patched are patched. Areas that cannot be patched are avoided (partial blends may be provided).
		Areas that can be patched are patched. Blends fail if there are areas that cannot be patched (partial blends are not provided).
		Patching is not performed. Areas that cannot be blended are avoided.
		Patching is not performed. Blends fail if there are areas that cannot be blended (partial blends are not provided).

Segment Blend to Match Face Segments

When selected, this option lets you create faces that are segmented to match the segments in the faces that own the defining edges. Otherwise, adjoining faces will be merged.

Segment Blend to Match Face Segments		Segment Blend to Match Face Segments

Rho Type

Appears when Shape = Conic.

Measures how far the blend shoulder is pushed into the corner towards the apex. Select from Relative and Absolute.

Tolerance

Lets you specify a distance tolerance for non-constant radius blends. Otherwise, the default distance tolerance from Modeling Preferences is used.

For more information, see Modeling Preferences.

If you are adding a blend to an edge that is already tolerant or across a tolerant edge, the blend must be greater than twice the tolerance on the edge or the edge being crossed.

Hierarchy for Allowed Overflow Resolutions in edge blends

Precedence when combining Preferences options
Blend Conditions Edge Being Blended Encountered Edge
When the convexity of the encountered edge is opposite that of the blended edge, and the encountered edge is smooth.
When the convexity of the encountered edge is opposite that of the blended edge, and the encountered edge is sharp.
When the convexity of the encountered edge is the same as that of the blended edge, and the encountered edge is smooth.
When the convexity of the encountered edge is the same as that of the blended edge, and the encountered edge is sharp.