Swung Surface


This topic will explain the Swung Surface function, and the optionsfound in it.This topic will also describe where to find the function,provide quick steps and an example on how to use it, and provide links to related topics.

The Swung Surface Function

The Swung Surface function is used to create surfaces using two wireframechains: the path (trajectory curve) and the profile.The profile is swungalong the path using the Z-axis of the Active UCS as the revolution axisfor the function.The geometry selection requires that the path is selectedin the XY plane, and the profile is selected in the XZ plane of the ActiveUCS.The path is selected before the profile with both using chain selection.Both the path and the profile can be open or closed chains.

Follow TrajectoryCurve

Follow ProfileCurve

Tip: Thereare three main points for successful swung surface creation:

1) The path must be selected on the XY plane of the Active UCS whencreating the surface.
2) The profile must be selected on the XZ plane of the Active UCSwhen creating the surface.
3) The Z-axis of the Active UCS is the revolution axis, so its locationin reference to the profile and path has an effect on the results.

To open the Swung Surface function:

  • In the Advanced Surfaces group, of the Create 3D tab, clickSwung Surface.

The parameters display in theData Entry Manager.

The Data Entry Parameters

  • Preview - Select the check box to enable the CAD preview, which displays what the result will be before you create it. Once all geometry is selected, the preview is shown.
    Preview - Clear the check box to turn off the CAD preview.

Trajectory Curve on XY plane


(Delete) - removes the highlighted item from the list.

(Reverse) - Changes the direction of the selected chain.

This list box will show the entity currently selected for the function.

Profile Curve


(Delete) - removes the highlighted item from the list.

(Reverse) - Changes the direction of the selected chain.

This list box will show the entity currently selected for the function.


  • Follow Trajectory Curve- the surface follows the location of the trajectory curve or path.

Follow Path

  • Follow Profile Curve -the surface follows the location of the profile.

Follow Profile

Note: The previoustwo options provide the same result when the start of the profile andthe path are the same distance (XY) from the origin.

  • Tolerance - defines themaximum amount of deviation allowed for the surface creation.

  • OK - finalizes the function.

  • Cancel - exits the function.

Quick Steps - Swung Surface

  1. Open the function and define the Data Entryparameters.

  2. Chain select the path on the XY plane ofthe Active UCS as explained next.

  3. Click near the end of the first chain entityto set the start of the chain.

    Hold Shift and click near theend of the last entity to set the end of the chain.

    Alternatively, you can hold Shiftand click the end of the last entity to set the start and end of thechain in one click.

  4. Chain select the profile on the XZ planeof the Active UCS using one of the methods described previously.

    The CAD preview is automatically created when you finish chain selectingthe profile.

  5. You can update the Data Entry parametersto see the changes in the CAD preview, if the Preview check box isselected.

  6. Click OK to create the surface.

    The feature is added to the CAD Tree.

  7. To close the function, click Cancel.


A BobCAD file was installed with the software and can be opened to followalong with this example.

Part 1) Open the Example File

  1. In the Quick Access Toolbar, click Open.

  2. In the Opendialog box, navigate to C:\BobCAD-CAMData\BobCAD-CAM V**\Examples.

  3. With SwungSurface Example.bbcd displaying in the FileName box, click Open.

Part 2) Open Swung Surface

  1. In the Advanced Surfaces group, of the Create 3D tab, clickSwung Surface.

    The parameters display in the Data Entry Manager.

Part 3) Select the Swung Surface Chains

The first step is to select the geometry and create the CAD preview.This way we can modify the Data Entry parameters and get visual feedbackof the result before creating it.

Chain Selection

Swung Surface requires two chain selections: the Trajectory Curve orpath (on the XY plane) and the Profile Curve (on the XZ plane).You canperform chain selection in one of two ways.You can click to set the startingentity of a chain and then hold Shift and click to set the ending entityof the chain, or you can hold Shift and click the end of the last chainentity.For Swung Surface, you can often use the second method.

  1. In the Parameters group, of the Data Entry Manager, select the Follow Profile Curve option.

  2. Press and hold Shiftand click to chain select the Trajectory Curve on the XY plane.Clicknear either end of the chain.

    Notice that the Trajectory Curve is selected on the XY plane of theActive UCS, and that the focus has shifted to the Profile Curve list.


    The start and end arrows display to show that the current chain selectionis finished.

  3. Hold Shiftand click to chain select the Profile Curve on the XZ plane.(Clicknear the upper end of the chain.)

    Note that the Profile Curve is selected on the XZ plane of the ActiveUCS.


    After chain selecting the profile curve, the CAD preview displays inthe Workspace.


    Notice the resulting surface.The profile curve follows the trajectorycurve while being revolved around the Z-axis of the Active UCS.(Also,the direction of the profile curve does affect the result when usingFollow Trajectory Curve as it defines where the profile starts andends in relation to the path.)

    You also have a choice to create the surface using the location ofthe selected profile curve.

Part 4) Modify the Data Entry Parameters

  1. In the Parameters group, of the Data Entry Manager, click Follow Trajectory Curve.

    The CAD preview updates to reflect the change.


    The surface now uses the location of the profile curve to define thetrajectory path.

  2. To create the surface as shown in the CADpreview, click OK.


  3. The Swung Surface is complete.To close theData Entry Manager, click Cancel.

The CAD Tree

After creating a Swung Surface, it is added to the CADTree.This allows you to modify the results after creating the surface.

Part 5) Modifying Geometry

In this part of the example, we move our profile curve to show a fewimportant processes.

  1. In the CAD Tree Manager notice the Swung Surface feature in the CADTree.

    You can click the feature name to highlight the surface in thegraphics area.

    A shortcut menu is provided to allow you to modify the feature.

  2. Right-click Swung Surface, and click Suppress/Unsuppressin the shortcut menu.

    We are temporarily suppressing the feature to make it easier to modifythe wireframe input.

  3. In the Move group, of the Utilities ribbon,click Translate.

  4. In the Data Entry Manager below End, setthe Z value to 2.000.

  5. Click to select the profile curve.


    The preview appears.

  6. To confirm the selection, press Spacebar.


  7. To close the function, click Cancel.

Part 6) Rebuild and Edit the Swung Surface Feature

  1. In the CADTree, right-click Swung Surface, and click Suppress/Unsuppress.

    The surface returns to the Workspace.

  2. Right-click SwungSurface, and click Rebuild.

    We are rebuilding the feature because we modified the input geometry.

    Notice that because we used Follow Profile Curve, the surface updatesto the modified profile geometry.


    Notice that Follow Profile Curve uses the Z-axis location of the profilecurve to create the surface.

  3. Right-click SwungSurface, and click Edit.

    This option allows you to update the Data Entry parameters for thefunction without the need to reassign geometry.


    The function opens with the CAD preview displayed as the geometry isautomatically pre-selected.

  4. In the Data Entry Manager, click Follow Profile Curve.


  5. To update the changes to the surface, clickOK.


The profile curve now follows the locationof the trajectory curve.

Active UCS and Revolution Axis

As a final note for Swung Surface, the location of the Z-axis of theActive UCS is an important part of the resulting surface as it is therevolution axis for the surface along the path.

The following images show the result of the same wireframe geometryused in the previous example, but created from a different UCS.Note thatthe following example shows more of a creative use of Swung Surface asit results in scaling or stretching of the surface in the XY plane.

Example Geometry and UCS





Img Img

This concludes the example.

Related Topics

TheCAD Overview