How to Use Loop Selection

Introduction

This topic explains how to use the loop selection options when selectingthe edges of solid or surface geometry to use as wireframe selectionsfor machining features.There are two loop selection options: ConstantZ and Loop Selection.

Selection

Constant Z

The Constant Z option is used to select one or more loops from the modelthat contain a constant Z-axis value along the entire loop.

Note: TheConstant Z loop selection option uses the Z-axis of the machining origin(which is defined in the Machine Setup) and not the Z-axis of the WCS(world coordinate system).

Loop Selection

The Loop Selection option is used to select one or more continuous loopsfrom the model.These loops may or may not have a constant Z-axis valuealong the entire loop.When using the Loop Selection option, the softwarehighlights two loops.After the two loops are highlighted, you click theloop that you want to keep at any location that is not shared betweenthe two possible loops.The other loop is removed and the desired loopis selected.The following sections explain how to use Loop Selection.

When to Use Loop Selection

The following list gives a few examples of when you can use loop selection.The Constant Z option is useful for selecting 2D chains with a constantZ-axis value.The Loop Selection option is useful for selecting 3D chainsor any loop that does not have a constant Z-axis value.

Loop selection is used:

When selecting feature geometry for 2-axis machining features
When selecting a boundary for 3-axis features or operations
When selecting geometry or boundaries for Multiaxis features

Using Constant Z

The following image shows an example part model and the machining origin(work offset) on the part.

During selection mode, point to the surfaceedge of the loop that you want to select.
While the surface edge displays in the currentHighlight color, right-click (click with the right mouse button) todisplay a shortcut menu.
In the shortcut menu, click ConstantZ.

The outer loop of the model is selected.

To confirm the selection, click OK.

The selection shown can be used to face thetop of the part, profile the outside of the part, or even apply a chamferor corner rounding operation to the top edge.

About the Z Axis Direction

The following image shows the same part model with a second work offsetdefined to face and pocket the side of the part.The new machining originZ-axis is not the same orientation as the first.

During the geometry selection, point to asurface edge, right-click, and click ConstantZ.
To confirm the selection, click .

Again, the selection shown can be used toapply a face, profile, chamfer, or corner round operation to the feature.

Multiple Loop Selection

The loop selection options are designed to assist you when selectingsolid and/or surface edges and you can continue to add or remove selectionsfor features in which more than one contour or profile is needed.

For the next example, we have a part withmultiple pockets to select for a 2-axis feature.

During geometry selection, point to the surface edge and right-click.

In the shortcut menu, click ConstantZ.
Repeat this process as many times as neededto select all of the feature geometry.
During the selection, we realize that wewant to select just one pocket and then use a Toolpath Pattern tohandle the remaining pockets.

You can click to remove selections from theautomatically selected loops.

Removing Loop Selections

In addition to the ability to make multiple selections, you can alsoadd or remove selections when using the loop selection options.

Point to the unwanted entity, and click toremove it from the current selection.
You can repeat this process to remove allunwanted entities.
After removing the unwanted selections, click to confirm the selection.

Note: To remove an entire loop from selection, simply repeat the process.If a loop is selected, right-clicking an edge of the selection and selecting Constant Z will deselect that loop.

The Constant Z option is extremely useful when selecting 2D loops.Whenyou need to select 3D loops from a model, you can use the Loop Selectionoption.

Using Loop Selection

The Loop Selection option is used to select a continuous loop from thegeometry that may or may not have a constant Z-axis value.What is importantto understand about using Loop Selection is that there are often two loopsto choose from when selecting a surface edge.In this scenario, when youclick Loop Selection, the software highlights both of the loops.It isthen up to you to select the loop that you want to keep.The proper wayto do this is explained next.

For the part in this example, we want to select the outer profile ofthe part to create a profile finish operation.The part geometry containswavy surfaces which can't be selected using Constant Z. Furthermore, thereis another pocket in the center of the top surface.If we selected thetop surface for the feature and let the software extract the edges, thenthe pocket in the center would be included in the selection.Loop Selectionmakes it much easier to select only the desired outer boundary as explainednext.

During selection mode, point to the surfaceedge of the loop that you want to select, and right-click.
In the shortcut menu, click LoopSelection.

Two potential loops are highlighted on themodel.

One loop is the outside edge of the top surface,and the other loop is the edge of the vertical face on the side of theopen pocket.The next step is to select the loop that you want to keep.

The Importance of Transparency and Shading

Before moving on with the example, there are a few helpful tips to assistyou in proper loop selection.When we clicked Loop Selection, the softwareautomatically highlighted two potential loops based on the surface edgethat we selected.The first tip is to use Transparency to better showthe two potential loops.

To better view the loops by making the part model transparent:

In the document toolbar, clickTransparent.(You can alsopress T, to toggle the transparencystatus of the part.)

By making the part transparent, it is mucheasier to view the two loops.This makes selecting the loop that you wantto keep much easier, as explained in the next section of this example.

In addition to the model transparency, youmay also want turn on and off the Shading of the part model.This is anotherway to make the two potential loops easier to view.(Turning off shadingcan also make it easier to select edges from complex solid/surface geometry.)

To better view the loops and aid in surfaceedge selection:

In the document toolbar, click Shaded.(You canalso press S to toggle theshaded status of the model.)

The tips provided about using the Transparentand Shaded View options can be useful in many situations when selectinggeometry for machining features, not just loop selection.

Select the Loop to Keep

In order to select the loop that you want to keep, click any entityalong the desired loop that is not shared between the two loops.Whenyou click the loop to keep, the other loop is removed from the selectionand you can then confirm the selection (you can also continue to makeselections or remove selections if needed).

For our current example, there is only one shared entity along the twocurrently selected loops.

The following image shows the entity that is shared between the twoloops (shown in blue).

Clicking this shared entity does not change the selection.

You can click anywhere else to select the loop that you want to keep.

Click the loop that you want to keep anywhere along the chainthat isn't shared with the other loop.

The unwanted loop is removed and the desired loop is now selected.
To confirm the selection, click .

With the selection made in this example,a profile (rough or finish) pass can now be applied to the selected loop.

Notice that we have selected geometry froma 3D model that is being used in the 2 Axis Wizard.To learn more, viewthe Related Topics links.

The loop selection tools are very helpfulwhen you need to select surface edges for machining features.

This concludes the example.