Point Generator

Command Activation

The Point Generator feature builds and tolerances 1D, 2D and 3D point features. This allows building of offline features when not connected to a coordinate measuring machine or when the production part is not available. The Point Generator also provides tools to build all motion path and can execute on demand the measuring of the new point.

The Circle Generator also provides a step and repeat function to create rows and columns of data points for capturing multiple point features.

figure 1, The Point Generator

To create a new feature, activate the generator by pressing <Ctrl + 5> simultaneously or by selecting [Measure→Auto Features→Point Generator] from the drop down menu. NOTE: the key press "5" is located on the number pad, not the row of numbers over the top of the keyboard.

Step 1 - Feature Characteristics

Complete the selections in the Feature Characteristics Group

1. Choose the Point type: 1D Points, 2D Points, 3D Points
2. Select Apply Tolerance if required.

When selecting a 1D Point type (-X, -Y, -Z, +X, +Y or +Z), a command button labeled <Auto IJK> will become available. This command when selected, will apply standard default values in the I, J and K controls located in the Target Parameters group. The ability to perform Step and Repeat capabilities are available only when 1D Point type has been selected.

Step 2 - Step and Repeat

The Step and Repeat function is available when 1D Point type has been selected.

Under The Step and Repeat group you have the option to specify rows and columns of data points that will be orthogonal to the current Part Coordinate System. The number of data points and spacing between the rows and columns are separately controlled.

figure 2, Step and Repeat Activated

To activate the Step and Repeat tool, place a check next to Use Grid: . Additional information will appear which allow you to abort the execution when using on a DCC style CMM.

Enter the parameters for the row and column count and spacing. The values you enter for spacing is sign sensitive. These spacing values are applied against the XYZ position entered in Target Parameters group which is considered the starting point of the grid.

The grid is assumed to be parallel to a PCS base plane and does not perform any contour walking capabilities. Those commands are better suited by the Scanning Tools within Geomet. For example: a -Z Point will expect a constant Z through the execution of the grid.

Step 3 - Target Parameters

Complete the values required in the Parameters Group

1. Enter the XYZ contact point location
2. Enter the IJK approach vector

NOTE: The IJK approach vector is defined as a direct line to the contact point that is perpendicular to the surface. Using the surface plate of your CMM as an example, we know the IJK surface vector is I=0.0, J=0.0, K=1.0. Therefore when we specify a -Z 1D Point, the surface normal would be I=0.0, J=0.0, K=1.0. If we select the <Auto IJK> command button, the IJK controls will populate with these values.

Some IJK values will be difficult to calculate when the surface is not parallel to a PCS Axis. If your inspection part has a CAD drawing associated to it, most CAD programs can easily provide the IJK values.

figure 3, IJK Approach Vector

It is not necessary to always approach the contact point along the IJK approach vector. When you teach an inspection program you generally do not control the CMM with such a high degree of motion accuracy. Therefore you should enter an IJK that allows direct line-of-sight approach to the contact point. In figure 3, we have a condition where the surface we need to measure has a restriction on approach. We must account for this by entering a IJK that provides a safe line-of-site approach to the contact point.

Our inspection requires that a -X 1D Point be used to contact the step. Under normal conditions, we would enter an IJK value of 1.0, 0.0, 0.0. However to clear the restricting surface, we used the approach vector 0.7, 0.8, 0.0. The Stand-Off Point would be created along that approach line.

To get a simple understanding, if we stood on the contact point, we would look at a line from the contact point alongside the restricting surface. In this example, we moved 0.7" along the X-Axis and simultaneously, move 0.8" along the Y-Axis.

When the Point Type selected is Vector Point, additional parameters will appear in the Target Parameters group. These include Probe Deviation, Plus and Minus Deviation, see figure 4.

figure 4, Vector Point Target Parameters

Vector Points are executed one-at-a-time. If you require a grid of Vector Points we suggest using the Vector Point Generator described here. A good description of the deviation fields and general information regarding Vector Points can be found here. A detailed explanation regarding Vector Point can be found in our technical notes section and titled:

Curved Surface Measurement with Vector Point

There are several tools available to build motion paths to ensure clear motion without collision into the inspection part, or 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.

This command acts upon the values displayed in the Point Generator and instructs the CMM to perform the inspection.

When executing a row / column grid, the CMM will start at the first point as defined in the Target Parameters group and move in column number 1 until reaching the required number of points. The CMM will then move to column number 2 (if required) and reverse direction to the bottom of column number 2. The CMM will continue this operation until all data points have been captured.

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