ACKNOWLEDGEMENT

I would like to place on record my deep sense of gratitude to Sir Manpreet, Faculty of Seimens, for his generous guidance, help and useful suggestions.

I am extremely thankful to Sir Minesh Vohra, COD, Lovely Professional University Jallandhar, for valuable suggestions and encouragement .

I am also thankful to Mr. Munish, Training officer, LPU, Jallandhar for providing the opportunity to get the knowledge.

Signature of StudentSatyam Sharma11005320

TABLE OF CONTENTS

Introduction

Curves used for creating freeform features Spline Selected Curves

INTRODUCTION

Course descriptionThis course addresses using NX modeling functions to build freeform shapes.Freeform shapes are those that cannot be built using standard analytic shapes (such as blocks, cylinders, spheres and some simple extruded or revolved features). This course includes creating splines and other developed curves, building surfaces through one or more sets of curves, sweeping profiles along guides, and applying specially shaped transitions between faces. The emphasis is on common techniques that lead to low risk results. If you use sound practices you can create models easily and that will dependably update model geometry such as hollows, offsets, thickened sheets, and trimmed bodies.Intended audienceThis course is intended for designers, engineers, manufacturing engineers, application programmers, CAD/CAM managers, and system managers who have the need to use NX freeform modeling.PrerequisitesBasic understanding of parametric/explicit modeling.Working knowledge of the following:• Essentials for NX Designers course• Basic understanding of parametric and explicit modeling, and the mastermodel concept.• Working knowledge of the following:o WCS manipulation.o Basic sketching or curve construction.o Using Expressions.o Using the Part Navigator.

ObjectivesAfter successfully completing this course, you should be able to perform the following activities in NX:• Create and edit splines and developed curves.• Create and edit of primary and transition surfaces using freeform curves and faces: Through Curve surfaces Through Curve Mesh surfaces Swept surfaces and bodies Section surfaces and bodies Bridge surfaces Face and Soft Blends N-Sided surfaces• Analyze curves and faces.

Introduction to Mechanical FreeformPurposeThis lesson provides an overview of typical processes to create freeform shapes.ObjectiveThis lesson will introduce you to some of the best methods to construct models containing freeform elements.

Freeform modelingFreeform shapes cannot be built using primitive bodies; standard features; or sketches containing only lines, arcs, and conics.DefinitionA freeform design process may include the following: • Creating splines • Building primary sheets or bodies using the following: o Through curves o Through a mesh of curves

o Sweeping profiles along guide strings • Applying specifically chosen transitions. • Editing freeform data from any source. • Constructing solid bodies partly or entirely from freeform sheets. Freeform models that are well constructed: • Are easily updated when appropriate edits are made. • May be used efficiently in downstream applications such as Manufacturing.

Methods for creating freeform shapesThere are three basic methods for creating freeform shapes in NX:• Exact modeling:In exact modeling, a shape is modeled as a complete set of wireframe (curves), and then surfaced. This is the easiest method for beginners. You can edit the surfaces and visualize the part as it is being developed. However, if you use this method, the surfaces may not have the best parameterization as they can wrinkle/bulge or show unwanted reflections.• Overbuilding primary sheets:For this method, curves are the basis but the sheets are oversized The sheets are trimmed to the intersections and the result is sewn together to create a solid. You can overbuild sheets when surface highlights and reflectivity are important. Bottles, lenses, lighting and similar products often make use of this workflow. This produces the highest quality surfaces, and is familiar to most users since the surfaces are curve based. However, this method is not intuitive and requires skill and experience. It requires the use of many trimming features that can make the model challenging to edit.• Direct modeling of sheet bodies:In this method, surface slabs are created in a freeform manner, then reshaped and fit into place using various direct modeling commands such as X-Form and Match Edge You can use direct modeling for a wide spectrum of industries, such as initial auto styling, to packaging, and toys, for example.This is the most direct of the methods and is similar to molding clay. However, this method requires the most skill and experience, and make editing difficult. This method is not a familiar methodology for experienced NX users.

Curves used for creating freeform featuresPurposeUnderstand and work with curves that are often used to create freeform features, including splines, offset curves, bridge curves, intersection curves, projected curves and others.ObjectivesUpon completion of this lesson, you will be able to:• Create offset curves• Create combined offset curves• Create curves offset in a face• Create bridge curves• Create intersection curves• Create wrapped curves• Create splines using an appropriate method

Overview of developed curvesA framework of curves is the basis of primary freeform features such as Through Curves, Through Curve Mesh, and Swept. When simple analytic curves (lines, arcs, conics) cannot create the required shapes, it is necessary to develop a suitable curve. You can develop curvesusing the following:• Projection of curves onto faces.• Intersection of faces.• Offsetting curves in a direction or in a face.• Computation from data.• Application of one or more rules (such as location, tangency, curvature, etc.) to other geometry.Offset CurveUse the Offset Curve command to offset lines, arcs, conics, splines, edges and sketches. Offset curves are constructed through points calculated normal to the selected base curves. You can choose whether to associate the offset curves to their input data. Curves can be offset within the plane defined by the selected geometry, to a parallel plane using the draft angle and height options, or along a vector you specify when using the 3D Axial method. Multiple curves can only be offset if they are in a contiguous string. The object types of the resulting curves are the same as their input curves, except for conics and curves created using the Rough Offset option or the 3D Axial method, which are offset as splines. Selection Intent options are available on the Selection Bar, to select the curves. If the input string is linear, you must define a plane by defining a point which is not colinear with the input string. This plane is used as the offset plane. Choose Information®Feature to open the Feature Browser dialog box, where you can view information on offset curves, such as lists of parents and lists of expressions used in the creation parameters. The following graphic shows the different types of offset curves you can create.— Distance type offset curve.— Draft type offset curve.— Law Control type offset curve

Where do I find it?• Choose Insert-Curve from Curves-Offset.• On the Curve toolbar, click Offset Curve

Offset curve optionsThere are four options for offset curces:• Distance — Creates offset curves at a constant distance, in the plane of the input curves.

• Draft — Offsets curves in a plane parallel to the plane of the input curves at a specified distance and angle.• Law Control — Offsets curves at a distance defined with the Law Function.• 3D Axial — Creates an offset of selected 3D curves by a given distance along a vector direction that you specify. The function also corrects the curves similar to rough offset, to maintain the specified distance between curves regardless of the steepness of the input curve. When you select 3D curves for offset, only the 3D axial offset is available. You can get information on associative offset curves, such as lists of parents and lists of expressions that were used in creation parameters when you choose Information→Feature.Trim OptionsYou can choose a method for trimming or extending the offset curves to their intersection points. The choices for trim method vary, depending on whether or not you use an associative output.Rough OffsetWhen you want to discard regions of self intersection in the offset string of curves you can use the Rough Offset option. The output of rough offset applied to splines is a single spline that approximates the input string at the specified offset distance.

ActivitiesIn the Curves used for creating freeform featuressection, do the following activities:• Create an offset curve• Create a 3D axial offset curve

Bridge CurveUse the Bridge Curve command to create, shape, and constrain bridge curves between curves, points, surfaces, or surface edges. You can also use this command to create symmetric bridge curves across a datum plane. This following graphic shows five bridge curves between a surface edge and points on a curve. The bridge curves are perpendicular to the surface edge at the intersection point.

Create and customize basic bridge curvesThis example shows how to create and customize bridge curves between the sheet bodies below. The final part includes four bridge curves and a Through Curve Mesh surface based on the curves.

1. From the Curves toolbar, choose .2. To define start and end points for the straight curve at the bottom of the part, select the curve ends at 1 and 2 .

3. To complete the first bridge curve, click Apply.4. To define start and end points for the second curve, select the curve ends At 3 and 4 .

5. To change the tangent magnitude from the start point, click the handle at , type 2, and press ENTER.

6. To complete the curve, click Apply.7. To create the final two bridge curves, select the start and end points and click Apply. The following graphic shows the final part, including a Through Curve Mesh surface based on the bridge curves.

Symmetric BridgeA symmetric constraint is useful when creating half of a model that is to be mirrored across a center plane. The symmetric bridge curve is automatically constructed when you set the following options in the Bridge Curve dialog box:• End Object (at center line) is set to Vector.• The vector is normal to the mirror direction across the center line.• G1, G2, or G3 curvature continuity is used. Procedure• Select the first curve.• Filter to Object. For symmetry.• Select a datum plane.• Select G2 or G3 Continuity to the datum normal.• Click Apply.

ActivityIn the Curves used for creating freeform featuressection, do the following activity:• Create bridge curves

Project CurveUse this command to project curves, edges, and points onto faces, faceted bodies, and datum planes. You can direct your projection toward, or at an angle to, a specified vector, a point, or along the face normals. The software trims projected curves at holes or edges of the faces. This example shows sketch curves projected along the –Z axis onto a sheet body.

ActivityIn the Curves used for creating freeform features section, do the following activity:• Projected CurvesCombined ProjectionUse the Combined Projection command to combine the projections of two existing curves to create a new curve. The two curve projections must intersect. You can:• Select curves, edges, faces, sketches, and strings.• Specify whether the new curve is associated with the input curves.• Specify whether you want to keep, hide, delete or replace the input curves.In most cases, this command creates an approximated B-curve. However, you can also create an exact curve without approximation if:• There is only one curve in each of the two original strings, which can be "matched" together internally by NX with the same number of poles, degrees and knots.• The deviation between each correspondent control pole of the two resulting matched curves is less than the current modeling tolerance along the "non-projection" direction, which is normal to the two projection vectors.

ActivityIn the Curves used for creating freeform features section, do the following activity:• Create a combined projectionIntersection CurveUse the Intersection Curve command to create intersection curves between two sets of objects.• Intersection Curves are generated between two sets of faces or planes.• Intersection Curves are associative and update according to the changes in their defining objects. They can be edited by adding or removing objects to or from the sets of intersection objects.• You can select multiple objects in the input sets to perform an intersection operation.• When possible, analytic curves (lines, arcs, and ellipses) are created; otherwise, a spline is created. The following graphic shows an example of intersection curves that are created where a sheet body intersects a solid body.

1— First set of faces or planes (body faces selected).2— Second set of faces or planes (sheet body).3— Intersection Curve feature.

Part Versions groupThe Part Versions group contains the Load list, with options to control how to find component parts.• As Saved loads parts from the directory in which they were saved.• From Folder loads parts from the same directory as the parent assembly.• From Search Folders loads parts from a list of search directories.

ActivityIn the Curves used for creating freeform features section, do the following activity:• Intersection curves

Offset Curve in FaceUse this command to create offset curves on one or more faces from connected edges or curves on the surfaces. The offset curves can be associative or non-associative, and lie at a specified distance from an existing curve or edge section. The curves are created on the face, and are measured along face sections normal to the original curves.

Curve on surface used to create offset curves

1. Selected curve on surface to offset. 2. Resulting offset curves on the surface.

• Different spanning methods let you fill the gaps between the curves. There are also options to let you trim against the selected face boundaries.• The resulting offset curves are either cubic splines or analytic curves, depending on the input curves and the faces from which they are offset.• The offset curves can be created outside, of off their faces if there is enough surface.• The Modeling Distance Tolerance parameter determines how accurately the offset curve approximates the true theoretical offset curve, although you can specify your own tolerance.• Use the same options to edit an Offset in Face feature that you usedto create it.

ActivityIn the Curves used for creating freeform features section, do the following activity:• Create offset in face curves

Wrap/Unwrap CurveUse the Wrap/Unwrap Curve command to wrap curves from a plane onto a conical or cylindrical face or unwrap curves from a conical or cylindrical face onto a plane. You cannot delete defining geometry, such as the wrapped face or faces, the Wrap plane, or the input curves until you remove all dependence on that geometry.

Wrap/Unwrap Curve terminology

1. Unwrapped cut line2. Unwrapped cone top3. Unwrapped cone bottom4. Cut line – an imaginary line that is some rotation of the tangent line around the axis of the cone or cylinder. This line affects where curves are placed after being wrapped or unwrapped.If a closed curve on the face of a cone or cylinder that completely surrounds the axis is unwrapped, it cuts at the cut line. This is the only time the cut line actually cuts anything. For all other curves, if the majority of a curve is to one side of the cut line, it will be unwrapped to the same side of the tangent line.

5. Tangent line – an imaginary line that lies on both the wrap face and the wrap plane where they meet. It is a straight line that is coplanar with the axis of the cone or cylinder6. Wrap face. For the Wrap option, this is the conical or cylindrical face to which selected curves on a tangent plane are wrapped. For the Unwrap option, selected curves on this face are wrapped onto a tangent plane.7. Wrap plane. For the Wrap option, selected curves on this plane are wrapped onto a tangent conical or cylindrical face. For the Unwrap option, selected curves on a tangent conical or cylindrical face are wrapped onto this plane

SplinesA spline is a standard curve in most CAD systems. Unlike lines and conic curves, the spline can be adjusted to virtually any shape in two dimensions or three dimensions. The term spline originated from a long flexible strip of wood, metal, or plastic used to lay out various curved shapes. Weights were attached to hold the spline in place. To modify the curve, the weights are moved. Spline mathematics simulates, and sometimes improves upon, the behaviour of physical splines. Splines are known as Non-Uniform Rational B-splines (NURBS). Their flexible nature and variety of data interpretation methods make splines the foundation of freeform modeling. The spline was constructed through five points using the Through Pointsmethod. The spline is constrained to pass through the selected points, represented by plus symbols (+). There are a corresponding set of poles. Poles are represented as circles. A series of lines connecting consecutive poles is called the control polygon of the spline. The fan shape is the curvature comb of the spline. The control polygon and comb are part of the analysis display of the spline, which you will study in greater detail later.

The following two splines were created using the same five points as Through Points spline illustrated on the preceding page. The first was created using the By Poles method, in which the points specified define a control polygon. The spline passes through only the first and last pole.

The second spline was created by the Fit method, in which the system approximates input points with a relatively smooth curve. The first and last points are on the spline. You can see that different construction methods produces dramatically different results.

Spline creation methodsNX offers three basic methods for creating splines:

• Studio splinesStudio splines can be created so they are associated with the points selected to create them. If the points change, the spline is updated. This is the recommended method for creating splines. There are two methods to create studio splines.o Through PointsThe spline passes through a set of specified points.o By PolesThe points specified define the control polygon of the spline. Only the ends of the spline pass through specified points.• SplinesThere are four methods for creating non-associative splines.o By PolesThe specified points define the control polygon of the spline.o Through Points.The spline passes through the points specified.o FitThe spline is fitted to the specified points. The spline does not exactly pass through any the points.o Perpendicular to Planes.The spline passes through one specified point, and is perpendicular to all the planes specified.• Fit splineYou can create a spline fitted to the specified points, that allows you to specify constraints as with studio splines.

Segmentation, knot pointsThere are two types of points associated with splines:Defining points - Used to create the spline.Knot points - Endpoints of the spline segments. The minimum number of points required for all splines is one more than the degree of the spline.

Spline dataThe following data is stored for a spline:• The degree of the curve.• An array of poles (vertices) for the curve.• Parameter values which define the segments of the curve.• Defining points (if created using through points).• Fit weight (if created using the fit method).Associative spline dataStudio splines created with the associative option are features. The associative splines appear in the Part Navigator. They must be edited using Feature methods, such as Edit Parameters, or by double-clicking in thePart Navigator. Associative splines are updated when changes are made to geometry selected for:• Points• Poles• Tangency constraints• Curvature constraintsTips for creating freeform curves• Use single segment splines whenever possible.• If you need more than two segments to capture a shape, consider framing the part with multiple curves. How you can do this is explained later in the course.• Use degree three splines when possible.• Use degree five splines to maintain curvature continuity with curves at both ends of a single segment spline.

Selected Curves

Most freeform construction methods covered in this course require the selection of curves. Depending on the type of feature being created, they are referred to as Sections, Guides, Primary Curves, or Cross Curves. Swept features require one to three Guides, with no limit on Sections. Through Curve Mesh and Through Curves features do not have a limit on the number of curves. Each set of selected curves can consist of a combination of curves or edges. Up to 5000 can be selected, if you have enough memory. However, we recommendthat the fewest number possible be used. Some features require that certain strings are planar, or must be tangent continuous. Each of these cases is described individually.

Primary and transition bodiesPrimary bodies (sheets or solids) are, in general, the main features that define a required shape. Transitions are secondary contours that define a blend or transition from one primary face, or set of faces, to another face or set of faces. Applications for primary sheet bodies Use sheet bodies for the following:• To create contours and shapes that would be difficult or impossible to achieve with standard solid modeling.

• To trim a solid body to create a contour or shape on one or more faces of the solid body.

• To create a solid body by creating and sewing several sheets together to totally enclose a volume.

U and V GridsFaces of sheet or solid bodies can be visually represented in Static Wireframe rendering by U and V grids and boundaries. Note that the U and V grid is a display feature only, not an analysis tool. Grid display may be useful to examine iso-parameter lines of a surface.

When a body is first created, the density of the grid is determined by the values in U Count and V Count on the General tab of the Modeling Preferences dialog box. You can change the grid display of an existing body.• Choose Edit→Object Display .• Select the object.• Change the values for Wireframe Display U V.To modify individual faces on a sheet or solid body, select Face on the Selection bar. You can also set the default color and font of grid lines by choosing Preferences-Modeling (Analysis tab)-Face Display group.

Freeform Construction Result optionsYou can use the options on the Freeform tab in the Modeling Preferences dialog box to set freeform feature construction and analysis display. The Freeform Construction Result options allow you to control the type of body created when using Through Curves, Through Curve Mesh, Sweep, and Ruled commands. B-Surface – Creates B-Surface faces, even ifthe generator geometry is planar. Plane – Creates trimmed Planar faces if the defining curves are coplanar. However, if you edit the defining curves so that they are no longer coplanar,the faces will automatically be converted to B-Surface.

Analysis tab optionsThe Analysis tab on the Modeling Preferences dialog box has the following options.Pole and Polyline Display — Lets you control the color and font of poles and the control polygon of a spline or face.Edited Pole and Polyline Display — Lets you control the color and font of poles and the control polygon of a spline or face when it is being edited.Face Display — Lets you control the color and font of the grid and knot lines of faces.

Determining the face typeYou can determine the type of face of a freeform feature by usingInformation→Object, and selecting Face on the Selection bar and then selecting the face. Or, you can choose Information→Object and use the TypeFilter (in the dialog box) to turn on Face, and select the faces. The information about the faces selected is displayed in a window.Modifying Parameters Edit Feature Parameters allows changing the parameters of anyparametric feature – freeform or not. It is found on the Edit Feature toolbar, or by choosing Edit→Feature→Edit Parameters and selecting the feature. Or you can edit them by right clicking the feature in the Part Navigator or in the graphics window, and choosing Edit Parameters. Edit with RollbackEdit with Rollback rolls the model back to a timestamp just precedes the one you wish to edit. It is accessed on the Edit Feature toolbar, or by choosing Edit→Feature→Edit with Rollback. This option works the same as Edit Parameters, but the edited feature—and all earlier features disappear during edit. It is accessed the same as Edit Parameters, or you can double-click the feature in the Part Navigator or in the graphics window..

TolerancesNot all surfaces use the tolerances specified on the Modeling Preferences dialog box. See the NX online help or technical documentation for a full explanation.

Distance ToleranceDistance tolerance is the maximum distance allowed between the true theoretical sheet and the resulting approximated sheet that NX creates. Methods using approximation require a distance tolerance. The distance tolerance can be set in the Modeling Preferences dialog box on the General tab.Angle ToleranceAngle tolerance is the maximum angle allowed between the normal of the true theoretical sheet, and the normal of the sheet that NX creates to approximate it. Some methods require an angle tolerance. If you increase the tolerance to a very large value, you effectively removethat tolerance from consideration. If you set tolerances to extremely small values, it can result in unwanted surface complexity.

Through CurvesUse the Through Curves command to create a body through multiple sections where the shape changes to pass through each section. A section can consist of a single object or multiple objects, and each object can be any combination of curves, and solid edges, or a solid face. You can do the following:• Use multiple sections to create a sheet body or solid body.• Control the shape of the surface by aligning it to the sections in a variety of ways.• Constrain the new surface to be G0, G1, or G2 continuous with tangent surfaces.• Specify single or multiple output patches.• Make the new surface normal to the end sections.

The Through Curves command is similar to the Ruled command. With Through Curves, you can use more than two sections and you can specify tangency or curvature constraints at the start and end sections.Alignment methodsAlignment methods are available in many NX commands. They allow you to control how the feature flows from one section to another. Following is a list of the methods. Not all are available in all commands.• Parameter — Spaces the isoparametric curve connection points at equal parameter intervals along the sections. NX uses the entire length of each curve. Parameter values vary according to curvature; the tighter the curvature, the closer is the interval. The following graphic shows the grid display of how the isoparametric lines are spaced when you use the Parameter alignment method.

• Arc Length — Spaces isoparametric curve connection points at equal arc length intervals along the defining sections. NX uses the entire length of each curve. The following graphic shows how the entire section length is divided into equal arc length segments to align.

• By Points — Aligns points between sections of different shapes. NX places alignment points and their alignment lines along the sections. You can add, delete, and move the points to preserve sharp corners or otherwise refine the surface shape. The following graphics shows a surface that transitions from a circular section to a rectangular one.

control the specific alignment of points in each section. It is recommended that you include alignment points at sharp corners. If you do not, NX creates high-curvature, smoothed corner bodies to approximate them, and any subsequent feature operations performed on the corners or faces, such as blends, shells, or Boolean operations, may fail due to the curvature.• Distance — Spaces points along each section at equal distances in a specified direction. This results in isoparametric curves that all lie in planes perpendicular to the specified direction vector. The defining curves determine the extents of the body, the body continues until it reaches the end of one of the defining curves. You can specify the direction in which the isoparametric curves are spaced. Internally, NX constructs planes which are intersected with each of the defining curves to obtain the points needed for the isoparametric curves.

• Angle — Spaces the points along each curve at equal angles around a specified axis line. This results in isoparametric curves which all lie in planes containing the axis line. The extents of the body are determined by the defining curves, the body continues until it reaches the end of one of the defining curves.

Create a through curves surfaceThis example shows how to create a basic Through Curves surface through six sections. Each section consists of two tangent curves.

1. On the Surface toolbar, click Through Curves or choose Insert-Mesh Surface-Through Curves.2. Set the Selection Intent rule. For this example, on the Selection bar, from the Curve Rule list, Tangent Curves is selected.3. Select a curve and click the middle mouse button to complete the selection of the first section. For this example, the first curve at the upper end is selected.

Since you selected Tangent Curves as your selection rule, two tangent curves are added to your model and displayed as Section 1 in the List box.

4. Select additional curves and add as a new section. For this example, each set of tangent curves is selected and added as a new section.

To avoid twisting and to ensure that each section points in the same direction, select the top curve at the upper end.

5. Click OK or Apply to create the Through Curves surface. The surface is created using the default options in the Alignment and Output Surface Options groups. For this example, the default Parameter alignment method is used.

6. Double-click the Through Curves surface to edit it. The Through Curves dialog box opens.7. In the Settings group, clear the Preserve Shape option to make other alignment methods available for selection8. In the Alignment group, from the Alignment list, select an option. For this example, from the Alignment list, Arc Length is selected. The surface isoparametric curves are realigned along the sections.

9. On the View toolbar, set the Rendering Style Drop-Down list to Shaded with Edges.10. Click OK to update the surface.

ActivityIn the Primary Sheets and Bodies section, do the following activity:• Compare Arc Length and Parameter Alignment

Through Curve MeshUse the Through Curve Mesh command to create a body through a mesh of sections in one direction, and guides in another direction, where the shape fits through the mesh of curves. This command uses sets of primary curves and sets of cross curves to create a bi-cubic surface.• Each set of curves must be contiguous.• The sets of primary curves must be roughly parallel and the sets of cross curves must be roughly parallel.• You can use a point instead of a curve for the first or last primary set. You can do the following:• Constrain the new surface to be G0, G1, or G2 continuous with adjacent faces.• Control cross curve parameterization with a set of spine curves.• Locate the surface near the primary curves or cross curves, or at an average between the two sets.

Curve Mesh constraintsUsing the Continuity section of the Through Curve Mesh dialog box you can constrain the body so that it is tangent to (G1), or curvature continuous (G2) with, a face or set of faces at the first or last primary and cross curve. G1 (Tangent) continuity—Lets you constrain the new body tangent to a face or set of faces. G2 (Curvature) continuity—Lets you constrain the new body tangent to, and curvature continuous with, a face or set of faces. When the constraints are created, they match the tangency and the normal curvature, in the tangent direction of the new body. You can match the constraints along common edges, as well as when the edges of the curve mesh body are in the interior of the constraint body. Constraints can be created during the initial creation of the curve mesh, or by editing it later. G0—Is location only.

Create a through curve mesh using curves and a pointThis example shows how to create a surface using a curve and a point as primary sets and other curves as cross sets.

1. On the Surface toolbar, click Through Curve Mesh , or choose Insert-Mesh Surface- Through Curve Mesh.2. Select a curve for the first primary set and click the middle mouse button or Add New Set . For this example, the curve at the top is selected.

3. On the Selection bar, enable Snap Point and set it to End Point.4. Select a point as the second primary set. For this example, the end point of the curve is selected as shown.

You must select the primary and cross sets in consecutive order, moving from one side to the other.

5. Click the middle mouse button twice to complete the selection of primary curves.

6. Select the sets of cross curves and click the middle mouse button or Add New Set after each set. For this example, each blue curve is selected as a set.

As you select each set of cross curves, the preview is updated to display the surface.7. Click OK or Apply to create the mesh surface.