Inventor and Its Applications 2010 � Copyright by Goodheart-Willcox Co., Inc.

Inventorand Its Applications

Student Web Si t eS tudent Web Si t e

Chapter 3A

Spline OptionsSplines are complex curves that you can adjust and calculate using a variety of methods.

You have the option of making adjustments directly after you create a spline, or changing any existing spline by picking the spline to display control functions. Spline control points provide most curvature options. Right-click with a spline selected or on a control point to access options for refining the spline shape. See Figure 3A-�.

Figure 3A-�. Options for controlling spline shape. Use the handlebars at each control point to make adjustments.

Handle

Spline controloptions

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Inventor and Its Applications 2010 2Copyright by Goodheart-Willcox Co., Inc.

Inventorand Its Applications

Student Web Si t eS tudent Web Si t e

Chapter 3A

NOTE

Most spline adjustments are only necessary for advanced spline sketching and analysis.

Specifying Fit MethodPick Fit Method to access a cascading menu with options for defi ning how spline points

are positioned in reference to the spline. The Standard option is active by default and displays smooth curves between spline points. Select AutoCAD to use the AutoCAD spline fi t technique. Pick Minimum Energy to create a spline with smoother and more even curves than those provided with the Standard fi t.

Displaying CurvatureChoose Display Curvature to add combs to the spline. See Figure 3A-2. When you select

Display Curvature, the Setup Curvature Display option becomes available from the shortcut menu when you right-click on a spline. Pick Setup Curvature Display to access the Curvature Settingsdialog box. The Curvature Settings dialog box contains sliders for increasing or decreasing comb density and scale. Comb adjustment may be necessary when you analyze splines, especially those with little or extreme curvature.

combs: Lines that indicate and compare the curvature of the spline for analysis.

slider: A movable bar that increases or decreases a value when you slide the bar.

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Inventor and Its Applications 2010 3Copyright by Goodheart-Willcox Co., Inc.

Inventorand Its Applications

Student Web Si t eS tudent Web Si t e

Chapter 3A

NOTE

The Display Curvature and Setup Curvature Display tools are available when you right-click on any curve. These tools are available from the Analysis panel of the Inspect ribbon tab.

Using HandlebarsA handlebar, or handle, appears at each control point, as shown in Figure 3A-�. Activate

a handle to adjust the spline by picking a handle grip. Drag the handle grips or constrain the

handlebar (handle): Linear bar tangent to spline control points; used for adjusting curvature.

Figure 3A-2.Adjustable combs help illustrate and analyze spline curvature.

Combs

Inventor and Its Applications 2010 � Copyright by Goodheart-Willcox Co., Inc.

Inventorand Its Applications

Student Web Si t eS tudent Web Si t e

Chapter 3A

handle using dimensions and geometric constraints. A handle must be active to be dimensioned and constrained. Figure 3A-3 shows the effects of dragging handle grips to adjust the original spline shown in Figure 3A-�, which appears to be constrained. When you make changes to spline curvature using a handle, the handle remains active. Right-click on a control point or handle and deselect Activate Handle to deactivate the handle. You must reactivate the handle to make changes to curvature.

Figure 3A-3. Adjusting spline curvature using handles. Notice the difference between this shape and the original spline shape shown in Figure 3A-1, with the adjustments made to this spline using handles.

Handlegrip

HandleCurvaturechange

Inventor and Its Applications 2010 5Copyright by Goodheart-Willcox Co., Inc.

Inventorand Its Applications

Student Web Si t eS tudent Web Si t e

Chapter 3A

Adding Curvature BarsRight-click on a control point or handle and select Curvature to add a curvature bar tangent

to the control point. A curvature bar appears with the handle. Drag the curvature bar grips or constrain the curvature bar using dimensions and geometric constraints. The curvature bar adds unique control to the spline by allowing you to dimension the curve radius. See Figure 3A-�.

curvature bar: Curved bar tangent to a spline control point that is used to adjust the curvature by specifying the curve radius.

Figure 3A-�.Adjusting the curvature of the spline shown in Figure 3A-1 using a curvature bar. The curvature bar provides the option to dimension the radius of the curve.

Handle

Curvaturebar

Inventor and Its Applications 2010 � Copyright by Goodheart-Willcox Co., Inc.

Inventorand Its Applications

Student Web Si t eS tudent Web Si t e

Chapter 3A

Flattening CurvatureRight-click on a control point or handle and select Flat to add a flat bar tangent to the control

point. The Flat option removes the radius from the specified spline curve. Drag the flat bar grips or constrain the flat bar using dimensions and geometric constraints. Adjusting the flat bar increases or decreases the size of the flattened portion of the spline. See Figure 3A-5.

Figure 3A-5. Adjusting the curvature of the spline shown in Figure 3A-1 using a flat bar. The flat bar allows you to increase or decrease the size of the flattened portion of the spline.

Handle

Flatcurvature

bar

Drag or dimensionto increase or

decrease the lengthof the flat curve

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Inventor and Its Applications 2010 7Copyright by Goodheart-Willcox Co., Inc.

Inventorand Its Applications

Student Web Si t eS tudent Web Si t e

Chapter 3A

NOTE

After making changes to a spline using handles, you can return the spline to the original shape by right-clicking on a specific control point or handle and selecting Reset Handle, or you can reset all modified curves using Reset All Handles.

Adjusting Spline TensionThe Spline Tension option allows you to adjust the amount of arc, or arc radius, between

spline points using the Spline Tension dialog box. Use the slider to adjust the spline curve tension from 0 to 100 and pick the check mark button. See Figure 3A-�. If you specify a spline fi t

Figure 3A-�.These splines were identical until the tension of the lower spline was increased.

Inventor and Its Applications 2010 8Copyright by Goodheart-Willcox Co., Inc.

Inventorand Its Applications

Student Web Si t eS tudent Web Si t e

Chapter 3A

method other than minimum energy and then increase spline tension, the fi t method automati-cally converts to minimum energy. Pick the Default button in the Spline Tension dialog box to return the default spline tension.

Additional OptionsPick the Insert Point option to add another control point to the spline. Pick a point on an

existing spline to insert the additional spline joint. Select the Close Spline option to change an open spline into one in which the start point and endpoint connect to create a closed spline.

ActivityActivityActivity 1. Launch Inventor if it is not already open. 2. Begin a new part fi le using the Part-IN.ipt or Part-mm.ipt template from the New File

dialog box. Do not open the actual template fi le. 3. Open a new sketch on the XZ plane and use the View Face tool to ensure that your line

of sight is perpendicular to the XZ plane. 4. Sketch a spline with two points and another spline with seven points. 5. Explore the spline adjustment options described in this supplement. 6. Save the part fi le as SUPP3-1.ipt. 7. Keep Inventor open for additional work, or exit if necessary.

1. Launch Inventor if it is not already open. 2. Begin a new part fi le using the Part-IN.ipt or Part-mm.ipt template from the New File

dialog box. Do not open the actual template fi le. 3. Open a new sketch on the XZ plane and use the View Face tool to ensure that your line

of sight is perpendicular to the XZ plane. 4. Sketch a spline with two points and another spline with seven points. 5. Explore the spline adjustment options described in this supplement. 6. Save the part fi le as SUPP3-1.ipt. 7. Keep Inventor open for additional work, or exit if necessary.