Line Generator

Command Activation

The Line Generator feature builds and tolerances 2D line features. This allows building of offline features when not connected to a coordinate measuring machine or when the production part is not available. The Line Generator also provides tools to build all motion path that can be executed on demand for the measuring of the new line.

The Line Generator provides complete access to define a line feature. The tool has two functions, its primary function is to create new features, it also provides access to editing an existing feature whether created by the generator or manually taught.

figure 1, The Line Generator

To create a new feature, activate the generator and follow these steps:

Step 1 - Defining the End Points and Hit Count

Complete the selections in the Parameters Group

1. Enter the XYZ PCS Values for End Points 1 and 2.
2. Select the number of hits required.

Step 2 - Feature Characteristics

Complete the values required in the Feature Characteristics Group

1. Select the projection plane, XY, YZ or ZX.
2. Select the reported PCS Pierce Axis.

Step 3 - Probe Direction

In the Probe Direction Group, select the appropriate probing direction.

Step 4 - Motion Path Adjustments

There are several tools available to build motion paths to ensure clear motion without collision into the inspection part, clamps and other obstacles. These include Clearance Coordinate Systems, offline IPs and Automatic IPs.

A complete description on Clearance Coordinate Systems can be found here.

Once the Clearance Coordinate System has been establish and set active, Offline IPs can be generated to build a motion path for safe CMM travel, see Offline IPs.

In most applications, the use of the command <Add Entry IP> and <Add Exit IP> will ensure safe transition for your CMM. The use of these commands requires that a Clearance CS is currently set active.

The Add Entry IP command calculates an IP directly over the feature in the normal base plane. For example, in the XY line example, the first Standoff Point is extracted and projected into the XY Base plane of the active Clearance CS. The motion will start directly over the line and plunge to the first SO safely.

The Add Exit IP command creates a similar IP to Add Entry IP except it will use the last SO.

The combination of these two commands instructs the CMM to safely position itself directly over the first and last SO respectively within the current Clearance CS base plane. The Entry IP will position the CMM directly over the first SO and commence the motion required for the measurement by moving directly to the first SO. All motion will be executed until the last SO is reached. Finally, motion will exit the feature by a direct line from the last SO into the Clearance CS base plane safely. In most applications, this sequence of events will be sufficient for safe CMM travel.

This command acts upon the parameters entered in the Line Generator and instructs the CMM to perform the inspection under motion.

While the <Execute> button performs the measurement on demand, the <Ok> command will process the feature record and append it to the current inspection. The <Ok> command is used when in a offline mode, editing an existing feature or building the inspection report without the need for immediate feedback.

The Relative Adjustment command will offset the current XYZ end points a specified distance. This is helpful when measuring similar features. An example would be a series of five +Y Lines 1.00" apart in the +Y direction. Build and Execute the first line using the Line Generator. When the feature has been completed, activating the Line Generator will display the last known values, or in this case, the parameters of line number one. Enter 0.0, 1.0, 0.0 in the Relative Adjustment group and press <Perform Adj>, the line XYZ end points will update. If you are using Entry and Exit IPs, they will update automatically. Press the Execute command and the CMM will transition and measure line number two.

This command is useful when learning to use the Line Generator. As shown in figure 2, the Review command displays the current settings and highlights any potential problems. Here we see a highlight (***CAUTION***) indicating there are no Entry or Exit IPs in the motion path.

figure 2, The Line Generator Review

The motion path does not show a clear path into the line and out of the line. You have to choose if this is acceptable based on your part. To return to the graphic display, press the <Review> button again.

The line end points will determine the full range of CMM motion. The CMM will move from end point 1 toward end point 2 inclusively. It is not always possible to locate safe end points that provides proper clearance for the current stylus during CMM motion. To illustrate, refer to figure 3, we have a production part with known end points at:

End Point 1:	X=4.500"	Y=1.000"
End Point 2:	X=3.500"	Y=2.250"
Probe Depth:	Z=-0.100"

 

figure 3, End Point Example

Enter the end point XYZ values in the Parameters Group. To allow for the size of the current stylus we will need to move the end points toward the center of the defined line. This ensures the stylus contacts the line away from the blended corners or other obstacles.

In figure 4, we have entered the nominal line end points as defined in the drawing. Processing the command <Probe Auto Adjust Clearance> will calculate new end points, moving them toward the center, see figure 5. The distance the end points are moved equals 200% of the current stylus radius. The stylus diameter used for this example is 0.100". Here we show the new end points:

End Point 1:	X=4.4375"	Y=1.078125"
End Point 2:	X=3.5625"	Y=2.171875"
Probe Depth:	Z=-0.100"

 

figure 4, Before End Point Adjustment	figure 5, After End Point Adjustment

Not all lines being measured are continuous between the endpoints. The line may have slots or other voids that will require the data points to be adjusted to prevent a bad data point being introduced into the line calculation.

figure 6, Data Point Exclusion Control

Removing data points from the final motion path can be accomplished with the Data Point Exclusion Control. As shown in figure 6, we have removed the data point at position number three.

The graphic display of the line contains four components for the line being generated. Starting at the top of the graphic, there is a vector length shown of 2.411600". This is the total length of the line between the end points. The next component below, shows the line between the end points displaying the data point contact locations. The third component displays the direction and expected motion path. The last component shown in the lower left refers to the PCS projection plane (XY) and the PCS Pierce Axis (Y) used for reporting.

To use this exclusion control, start by identifying the data point you will remove from the motion path. The slider control, when moved, displays the XYZ coordinates for that contact point. In the graphics, a small green square will follow the slider as you move it to identify the data point being selected. There is also a list located below the slider that lists the data point by the vector distance from end point one.

To exclude a data point, slide to the data point and press the button <Delete>/Add. When deleted, the graphic will show a continuous path over the previous site of the data point. The list will add the text "(removed)" behind the listing for that data point. The <Delete>/Add button is a toggle which will replace a data point that has been removed.

A second method of toggling the state of a data point involves the use of the list control. Highlight the data point and double left-click which will toggle its state.

NOTE: You can change the number of data points required for the line while data points have been removed. By changing the number of hits, you will slide the data points along the line to correspond to the changed number of data points.

This check option exaggerates the distance of the stand off distances in the graphic display. The Line Generator graphics scales the relationship of the line and its motion path. If the line is large, or the stand off distance is small the graphic displays the motion path too close and becomes hard to distinguish. Select this option by checking which will double the standoff distance only for displaying.

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