Plane Generator

Command Activation

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

The Plane Generator tool has two functions. The first is to create a new feature. The second provides access to editing an existing feature whether created by the generator or manually taught.

NOTE: When editing a plane feature that was not created with the Plane Generator care must be taken to account for IPs that may be inserted between the first and last Stand Off. The Generator does not retain those IPs.

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

Step 1 - Defining the boundary of the plane

Complete the selections in the Parameters Group

1. Select the probing direction.
2. Enter the four XYZ corner end points.
3. Select the number of rows and columns

Step 2 - Feature Characteristics

Complete the values required in the Feature Characteristics Group

1. Reverse IJK if required.
2. Select the reported PCS Pierce Axis.

Step 3 – Exclusion Zones

Exclusion Zones are added to the plane to account for portions of the surface where a hole or slot may cut through. Data points defined by the row and column positions may fall within these exclusion features. The Exclusion Zones removes those data points from the final motion map.

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.

Creating Offline IPs and Automatic IPs

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

Special Interim Point Commands

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

The Add Entry IP command will calculate 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 as its reference. The combination of these two commands results in the CMM moving directly over the first SO, perform the measurement and exit the line safely.

Defining the Corner End Points

The Plane Generator defines the boundary of planes as having four straight sides, shown here are some examples:

figure 2, Acceptable	figure 2, Acceptable
figure 2, Acceptable	figure 2, Not Acceptable

The shape of the enclosed area can be a wide variety, however there is one rule the shape must follow. That example can be seen in the right image where one end point is inside a straight line drawn between its adjoining corners. The Plane Generator will test for this condition and prompt you to correct it.

Entering End Points

figure 6, Corner Endpoint Tool

Press the button <Set End Points> to launch the Boundary Corner Endpoints dialog. The simplest method is to enter the XYZ values for each corner directly into the cells.

<Capture>

If you have a CMM attached and your part is available you can use the <Capture> function. When you press <Capture> Geomet will prompt you to take 4 data points. Capture the 4 data points around the boundary of the surface where you want your plane measured. As you make contact, the data points XYZ position will update in the dialog.

These Points are entered as surface points

When checked, the entered XYZ corner points are on the surface of the plane. This is important when working off line of the CMM. When you capture the end points using the CMM, the XYZ values are not compensated for the probe direction. The information for the plane normal has not yet been developed.

<Recall Last>

The Plane Generator writes the 4 end points out to the registry for recall at a future time.

Building the Motion Map Example

figure 7, Endpoints Set

In our example, we will use a 1-2-3 Block with the standard 6 holes through the part. The PCS is defined on the part and its origin is located on the lower left corner.
The four end points were manually entered and are:

	X	Y	Z
Endpoint 1	0.000	0.000	0.000
Endpoint 2	3.000	0.000	0.000
Endpoint 3	3.000	2.000	0.000
Endpoint 4	0.000	2.000	0.000

In the Boundary Corner End Points dialog, we placed a check on the “These Points are entered as surface points” option. When this was finished, we pressed the <Ok> button. The graphic area will now update showing the data point spread.

Rows are set at 20 and columns are set at 15. The Plane Generator will display the data point distribution based on this data. Please note the calculated IJK values are:

I	J	K
0.0000	0.0000	-1.0000

This indicates the plane vector normal is pointing downward from the surface of the part. Our plane has a real vector normal of:

I	J	K
0.0000	0.0000	1.0000

To correct this, press the <Reverse IJK> button. It is important that the vector direction is correct when building the motion path. With the vector normal now pointing “up” the probe path will be generated above the part.

figure 8, Incorrect IJK, Probing from the bottom	figure 9, Correct IJK, Probing from the top

Data Point Edge Clearance

figure 11, Enter Scale Value

In our example we are using a 1-2-3 block and our endpoints that define the plane boundary are the real edges of the part. This is not a good practice as our CMM will move to the exact edge and capture data points. Since our stylus is a sphere, we will get questionable data points that will result in an erroneous solved plane.

To remedy this condition we could have entered corner points that are inside the physical boundaries, or we can scale our endpoints using the Scale tool.
The value you enter in the Scale Dialog is a percentage of the total boundary area.

With the scaling operation completed, we now have a safe distance between the edge of the physical part and where the data points are captured.

Exclusion Zones

To eliminate data points from the grid, the Plane Generator provides three tools.

Exclusion Zone Tools
	Radial Exclusion Zone defined by a center point and radius. All data points that fall within this zone will be removed from the motion map. The Radial Exclusion Zone is a fixed position that does not scale.
	Boundary Exclusion Zone is defined by 4 endpoints. All data points that fall within this zone will be removed from the motion map. The Boundary Exclusion Zone is a fixed position that does not scale.
	This tool creates a small 0.05” radius Target Exclusion. The center position of the zone is positioned with mouse. As you position over a existing data point, an anchor shows, left click to set the zone.

Radial Exclusion Zone

figure 12, Radial Definitions

The Radial Exclusion Zone is used to delete data points from the motion map where a hole might exist on the surface that would interfere with measuring of a plane. There are many options available in building Radial Exclusion Zones.

Basic Radial Exclusion Zone

Using our 1-2-3 block example we have 6 holes, or areas where no data points should be taken. Enter the XYZ center for the first hole:

X	Y	X
0.5000	0.5000	0.0000

Now enter the radius of the hole, which is 0.250” and press <Ok>. The example below shows the removal of data points for that one exclusion zone.

figure 13, One Radial Exclusion Zone	figure 14, Enlarged Exclusion Zone

Care should be taken when entering empirical sizes for the exclusion zone. Although the radius of the hole is 0.250”, that will not take into account position changes or a chamfer on the edge of the hole. To account for this use the tools available in the Clearance Compensation Group. We could place a check next to Add and enter a value of 0.035 in the Additional Amount control. This will be added to the entered radius value and enlarge the exclusion zone as shown in figure 14.

figure 15, Radial Definitions

Should you have selected Subtract in the Clearance Compensation Group, the radius would have been reduced by that amount.

Building these exclusion zones can be done efficiently if you have your inspection piece on the CMM. Each zone can be built by capturing data points around the exclusion zone on the actual piece.

Place a check next to Multiple Capture and press the <Capture> button. Geomet will respond with a prompt for you to capture 4 data points. Capture data points surrounding your remaining holes on the 1-2-3 block example. When you finish with the exclusion zone, you will be prompted to continue capturing data points on the next zone.

When you have finished building all the exclusion zones using the CMM capture method, press <Cancel> to stop the capturing process.

figure 16, Multiple Exclusion Zones	figure 17, External Exclusion Zone	figure 18, Plane on tube end

External Exclude

When this option is checked, only the data points inside the radial zone are kept. All data point outside are excluded, see figure 17. This can be used when measuring a plane on the end of a cylinder and if combined with an Internal Radial Exclusion Zone, you can actually measure a plane on the end of a tube, see figure 18.

<Clear Entries>

Deletes all entries in the Parameters Group and preserves the check states.

Boundary Exclusion Zone

figure 19, Boundary Exclusion Tool

The Boundary Exclusion Zone is used to delete data points from the motion map where a void might exist on the surface that would interfere with measuring of a plane. There are many options available in building Boundary Exclusion Zones.

Basic Boundary Exclusion Zone

The simplest method to create a Boundary Exclusion Zone is by entering four endpoints that correspond to the area on your part that should be excluded from data points. In the left example below, we show a simple 0.5” x 0.5” exclusion zone.

figure 20, Basic Entered Exclusion Zone	figure 21, Captured Exclusion Zone

Using the <Capture> option, we can utilize the CMM and capture 4 data points that surround the area we want excluded, see figure 21.

Target Exclusion

The Target Exclusion Zone is used to delete single data points from the motion map where a void might exist on the surface that would interfere with measuring of a plane. This method work interactively with the graphic display to locate data points for removal.

When you activate the Target Exclusion mode, your mouse becomes the pointing device to locate data points. Pass your mouse over the graphic area and the pointer changes into a crosshair and arrow.

figure 22, selecting Data Points for Exclusion	figure 23, Targeting Exclusion Zones

Move the mouse over a data point and when over that data point, it changes into a larger green symbol. Left click and that position is captured and a small Radial Exclusion Zone is placed there.

Redraw Graphics

figure 24, Data Point List

This command refreshes the graphic display.

 

Delete All Exclusion Zones

This command deletes all exclusion zones.

 

Display Data Point List

This command produces a window that contains the full list of all data points.

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Related Procedures:

Auto-Direction, Origin, System Options, Introduction to Tolerance, Motion Edit, Disable Motion, Clearance CS, Offline IPs, Planar Profile Tutorial, Planar Profile