Autodesk Inventor - Using Splines and Surfaces

Using Splines and Surfaces

Inventor R2010Estimated Time Required to Complete: 30 minutes

This Skill Builder explores the tools available for creating and controlling the shape of splines. Surfaces are used to shape the part andto define the body split contours.

In This Exercise

In this Skill Builder, you learn how to:

Create and define splines.Loft with a rail.Create surfaces.Replace a face.Extend surface edges.Split the part into multiple bodies.Use the Emboss command.Create a Grill.

Prerequisites

Have Inventor 2010 installed.Understand how to open, create and save part files in your active project.Understand the fundamentals of solid modeling.Download (and unzip) the zip file containing the source file to use during this exercise to a folder in your active project.

Download

spline_1.zip (zip - 1902Kb)The zip file contains two Autodesk Inventor 2010 part files named spline_1_start.ipt and spline_ 1_complete.ipt. It also containsan animation (spline_1.swf) which demonstrates basic spline functionality.

System Settings

On the Application Options, Sketch tab enable the following settings:

Edit dimension when created.Autoproject edges for sketch creation and edit.Autoproject part origin on sketch create.

The Grid lines display is not enabled in any of the sketch environment images in this Skill Builder.

Note: You can specify the icon color scheme in Application Options. The appearance of the icons presented in this Skill Builder maydiffer if you are not using the color scheme noted in the following image.

Autodesk - Autodesk Inventor Services & Support - Using Splines and S... http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=135231...

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In the first section of this exercise, we will create two spline cross sections and one spline rail to use in a Loft operation.

To begin, open the file spline_1_start.ipt and orient to the Front view on the View Cube.

Notice that the part is wedge shaped and one end is wider than the other.

1.

Start a 2D sketch on the face indicated.2.

Start the Spline command. Refer to the following image for placement. Place a fit point at the mid-point (green dot) of thevertical line on the left (1), another directly above the origin (2). Double-click to place the final point (3) at the mid-point of thevertical line on the right. This action creates the spline. You can also right-click and choose Create to finish the spline segment.

3.

Right-click and select Done or press the Escape key to exit the command.

Note: Fit points at the end of a spline are square. Fit points along the curve are diamond shaped so you can identify the startand end of joined spline segments.

When you create a spline, handles appear at each fit point in a passive state. Handles are shape manipulators. You can drag ordimension to a fit point without activating a handle. If the handles are not visible, select a spline in the sketch to display the activeand passive handles.

4.

Activate the handle on all fit points. To activate a handle use one of the following methods:

Press and drag anywhere on the handle.Right-click a fit point and choose Activate Handle in the context menu.

Tip: Handle manipulation changes the shape of a spline. It is sometimes necessary to “undo” a spline handle manipulation.Depending on how many handles were manipulated, a normal Undo command might not produce the required results. When aspline is selected, there are two context menu commands available for reversing handle manipulations:

Reset All Handles Reverses all handle edits and restores the spline to the natural solve state. Active handles remain active.

5.


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Reset Handle Reverses a handle edit on a selected fit point or handle, or the handle nearest the cursor. The reset uses thecurrent spline shape. If other handles were modified, the reset may not return the handle to the original solve state. Thehandle remains active.

Right-click the middle fit point and enable Curvature in the context menu.

Tip: Enabling Curvature also activates the linear handle. Enabling the linear handle does not activate Curvature.

6.

Place a horizontal constraint on all handles.7.

Place a vertical constraint between the middle fit point (not the handle) and the part origin.8.

Place a dimension on each handle with a value of 1. A linear handle dimension is unitless and indicates the distance thespline is tangent to the handle.

9.

Place a radial dimension of 110-mm on the middle fit point curvature handle. A radial dimension is not a unitless dimension.10.

Place a 9-mm vertical dimension from the projected Origin point to the middle fit point.

The following image shows the completed sketch.

11.

Finish the sketch. The 9-mm dimension persists; the handles and all handle dimensions are visible only when the spline isactive.

12.

Start the Save As command and save the file as Spline_Skills1.ipt.13.

To create an exact duplicate of the spline on the other side of the part perform the following steps.

Orient the part to match the view in the following image and start a new sketch on the indicated face.1.

Start the Project Geometry command and project the spline to the new sketch.2.


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Finish the sketch.3.

In the next portion of the exercise, we will create the rail or “guide curve” to use in the lofting operation.

Orient the part so the narrow end is facing you as shown in the following image.1.

Start a new sketch on the narrow end of the part on the face indicated.2.

Start the Spline command and sketch a spline from the midpoint of the projected vertical line to a point above the midpoint ofthe part. Place the final point at the endpoint of the opposite projected vertical line. Double-click the last point to create the spline.

3.

Choose Done from the context menu or press the Escape key to finish the spline command.4.

Place a vertical constraint between the middle fit point and the midpoint of the projected line.5.

Place a 7-mm dimension from the midpoint of the top edge to the middle fit point.6.

Choose Done from the context menu or press the Escape key to finish the dimension command.7.

Right-click the middle fit point and choose Flat from the context menu. The mid-section of the spline now has zerocurvature. Although not required for this exercise, a unitless dimension can be applied to the handle to extend the length of the flatsegment.

8.


Save the file.10.

In the next section, we will create a lofted surface using the two parallel splines as cross sections, and the front spline as the drive rail.

Start the Loft command.1.

On the dialog box, choose Surface for the Output.2.


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Select the two parallel splines to satisfy the cross sections.3.

Change the selection type to Rails using one of the following methods, and then select the spline you created as the drive rail:

Right-click and choose Select Rails in the context menu.Select Click to add on the dialog box in the Rails pane.

4.

Click OK to create the surface.

The new surface appears in the browser as a lofted feature and also in the Surface Bodies folder.

Tip: A Surface is initially translucent and a single color. To change the appearance of a surface to opaque, select the surface(in the bodies folder or the browser). Use the context menu to cancel the Translucent selection. Select Properties in the contextmenu to assign a new surface color if required.

5.

In this section, you will use Replace Face to change the top of the object to match the shape of the new surface.

On the Model tab, Surfaces panel, choose the drop-down arrow to expose all available commands from the expanded panel.1.

Select Replace Face.2.


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Select the top planar face to satisfy the Existing Faces selection. Change the selection to New Faces and select the loftedsurface to satisfy the New Faces selection.

3.

Click OK to replace the planar face with the lofted surface.4.

In the browser, select the lofted surface and turn off the visibility in the context menu.

The top of the part now conforms to the shape of the surface.

5.

Start the Shell command.6.

Specify a 2-mm thickness. Do not remove any faces. Use the default Inside shell option.7.

Select OK to complete the operation.8.

Save the file.9.


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The interior of the part is now hollow. In the next section of the exercise we will use a top-down workflow to split the part into multiple solidbodies.

On the Surface panel, select the Thicken/Offset command.1.

In the graphics area, select the top of the part to satisfy the selection.2.

On the dialog box, select Surface for the Output. Enter a distance value of 3-mm. Use the flip direction arrow to offset the surfacetowards the interior of the part.

3.

Select OK to create the offset surface and finish the command.

Notice that the offset surface does not extend to the outside edges on the sides of the part. To use the surface to split the part intotwo bodies, all edges of the dividing surface must meet or extend beyond the edges of the part.

4.

On the Surface panel, click the drop-down arrow to expose all available commands.5.

Select the Extend command in the drop-down.

6.

Select the two outside edges of the offset surface to satisfy the Edges selection. Specify an offset value of 7.5 mm. Click OK to7.


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finish the command.

On the Modify panel, click the Split command.8.

On the dialog box, select the Split Solid option.9.

Select the offset surface as the Split Tool.10.

Click OK to split the part into two solid bodies and finish the command.11.

In the browser, turn off the visibility of the offset surface. Because the extended edges are dependent on the offset surface, thefeature visibility is controlled by the originating surface.

12.

Expand the Solid Bodies folder in the browser. Note that there are now two solid bodies present in the file. You can control thevisibility and color of each body individually.

13.


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Save the file.14.

In the next section, we will create a spline profile and surface for another split tool.

Start a new sketch on the bottom of the part.1.

Orient the part view as shown in the following image with the wide end of the part on the right.2.

Create a spline with five fit points as shown in the following image. Double-click the last point to create the spline. It is of noconsequence if the handles on your spline do not match the image.

3.


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Place a vertical constraint between the following fit points:

1 and 52 and 4

4.

Place a horizontal constraint between fit point 3 and the projected origin point. spline_10.png5.

Enable all linear handles on the spline using one of the following methods:

Right-click and select Activate Handle in the context menuPress and drag anywhere on a handle.

6.

Right-click the middle fit point and enable Curvature.7.

Place a vertical constraint on the handle at the midpoint and the two endpoints.8.

Place a unitless dimension of 1 on each linear handle.9.

Place a 12-mm radial dimension on the curvature handle at the midpoint.10.


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Add an angular dimension of 34 degrees between the linear handles and the edges of the part as shown in the following image.11.

Dimension the fit points as shown in the following image.12.


Start the Extrude command. Set the Output to Surface and select the spline to satisfy the Profile selection. Set theDistance to 40-mm. Reverse the direction of the extrusion so the profile intersects the existing bodies. Click OK to create thesurface.

14.


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Save the file.15.

In the next section, we will use the new surface to split the part and create a third body.

On the Modify panel, choose the Split command.1.

On the dialog box, select the Split Solid option.2.

Select the extruded surface as the Split Tool.3.

If only one body is visible in a multi-body part, Inventor selects the visible body as the solid to include. Because more than onesolid body is visible, select the upper body to satisfy the Solid selection.

4.

Click OK to create the body.Notice there are now three bodies in the Solid Bodies folder in the browser.

5.

Expand the Solid Bodies folder in the browser. browser_multi_body.png6.


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Right-click each body in the folder and select Properties in the context menu. Change the Body Color Style for each body to aunique color.

7.

Save the file.8.

In the next section, we will offset the new surface to create a clearance area between the two bodies on the top of the part.

Expand the Solid Bodies folder and select the new body.1.

With the body highlighted, right-click and select Hide Others in the context menu. It isolates the body you want to workon.

Notice that the context menu also contains the Show All command to unhide all bodies.

2.

In the next section, we will create an offset surface to use as a trimming tool.

On the Model tab, Surface panel, start the Thicken/Offset command.1.


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On the dialog box, set the Output to Surface and pick the extruded surface to satisfy the selection. Set the direction of the newsurface to the interior of the body. Set the Distance to 2-mm. Click OK to create the surface.

2.

Turn off the visibility of the extruded surface.3.

Start the Split command.4.

Select the Trim Solid option; select the surface as the Split Tool. Make sure the side to remove is pointing away from thematerial.

Note: Rotate the model to verify the side to remove arrow is pointing away from the solid. You can also select the secondRemove direction and not the one indicated in the following image. It is acceptable as long as the output is correct.

5.


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Choose OK to remove the material.6.

Turn off the visibility of the surface.7.

Turn on the visibility of all solid bodies. Notice the 2-mm gap between the bodies.8.

Save the file.9.

This completes the spline and surfacing portion of the exercise. To complete the part you can continue the exercise.

In the next section, we will create the embossed feature.

Turn on the visibility of the Emboss Sketch in the browser.1.

Turn off the visibility of the bottom solid and the large upper solid.

Note: Turn off the visibility of the non-participating solids to allow Inventor to choose the body to be operated on automatically.

2.

Start the Emboss command.3.

Set the Depth to 3-mm.4.

Select the Emboss from Face option.5.


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Click OK to create the embossed feature.6.

Start the Fillet command.7.

On the Fillet dialog box, enter 2-mm for the Radius value.8.

Select the dropdown and set the fillet type to Smooth (G2).Click the pencil icon to change to a selection mode.

9.

Pick the upper and lower edges of the emboss feature, and then click OK to create the fillets.10.


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Save the file11.

In the next section we will create a vented opening called a Grill.

In the Solid Bodies folder, make sure the visibility of the bottom solid and the embossed solid is off. Make the large top solid visible.

Tip: If you turn off the visibility of bodies, Inventor will not include them in a feature operation.

1.

Turn on the visibility of the Grill Sketch in the browser.2.

On the Model tab, Plastic Part panel, click the Grill command.3.

On the grill sketch, select the large outer ellipse to satisfy the Profile selection in the Boundary tab. Accept the default settings forsize.

4.


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Select the Island tab and then select the small center ellipse to satisfy the Profile selection. Accept the default of 0-mm.5.

Select the Rib tab and then select all the remaining line geometry to satisfy the rib selection. Accept the size defaults.6.


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Click OK to create the grill.7.

Turn on the visibility of all bodies.8.

Save the file.9.

Congratulations, you completed the Spline and Surfacing Skill Builder.

Let’s review your accomplishments...

SummaryIn this Skill Builder you:

Created and dimensioned splines.Manipulated spline handles.Created lofted and extruded surfaces.Created multiple bodies in a part file.Used Replace Face to change part contour.Extended surface edges.Used the Emboss command.Created a Grill.


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Autodesk Inventor - Using Splines and Surfaces