Plane

Command Activation

b	Measure→Plane
Keyboard	Main Menu	Toolbar

Planes have locations, attitudes and directions. The location of a plane is defined as the point at which it is pierced by a PCS axis. The attitude of a plane is defined by the projection angle AX/Y, AY/Z and AZ/X of the plane normal in each of the three PCS base planes, with range values from 0° to ± 180°.

figure 1, Plane represented in the working PCS

The direction of a plane is defined by the vector normal, pointing out of the plane. Figure 1 shows a plane with its projection into each PCS base plane. The normal, when projected into each PCS base plane provides the attitude in angles, see figures 2, 3, 4.

figure 2, AX/Y Projection	figure 3, AY/Z Projection	figure 4, AZ/X Projection

The Plane feature may be used to measure non-skewed planes. The printed pierce point of a measured plane is determined by the PCS axis that is most parallel to the normal of the measured plane. In the example in figure 1, the pierce point would be report as a Z axis point. Planes which are essentially parallel to PCS base planes have only two attitude angles which are meaningful, the third is printed in lower case, as for example "ax/y" to indicate its reduced significance.

figure 5, Direction Selector	figure 6, Out-of-Form Warning

To measure Planes press the Plane key < b >for a 4 point (or the default number of hits as established in System Options) plane, or < shift +  B > for a multi-point plane.

figure 7, Enter Data Point Count

If you required additional data points even during point capture, you can repeatedly press the Plane key which increments the required number by one. If Auto-Direction is not enabled, you will be prompted to enter the probing direction, see figure 5. Upon completion of gathering your data points, Geomet will test the form error to the newly calculated plane. If the form error exceeds the default setting, see figure 6, you will be prompted to < Accept > or < Re-Measure > the plane.

The definition of the Boundary Plane is a plane the passes through the minimum or maximum extreme data point of a measured or constructed plane and parallel to that reported plane. This plane can be used in all cases which a measured or constructed plane is be used such as PCS components, constructions and tolerance.

figure 8, Boundary Menu	figure 9, Example of Boundary Plane

Geomet offers two directions from which you can choose from, Upper and Lower. The Upper Boundary Plane represents the plane constructed at the most positive side of the reported pierce point. For example a plane reported at Z: +1.345 might have an Upper Boundary Plane reported at +1.349.

To use the feature, measure or construct a plane, select the plane directly on the report by left-clicking our mouse over the feature to highlight it . Activate the feature menu by right-clicking and a menu similar to the one shown in figure 7 will pop-up. Choose Upper or Lower Boundary Plane and the feature will recalculate showing the new reported values.

It is suggested to recall the plane, then apply the Boundary plane change to the recalled plane. This ensures the original plane is available for other construction or tolerance requirements.

If you do not have the Upper/Lower menu selections in your pop-up, the plane you have selected is referenced by another operation. You can only change the reported values on planes that have no reference. However you can recall the plane and then apply Upper/Lower Boundary Plane.

One example in which this feature can be used is to determine the width of a slot, see figure 10. Where the effective distance is the closest two points as if a gage block were used to identify the width of a slot. Select the plane representing one side of the slot and report it as an upper boundary plane, then select the opposite plane and report it as the lower. Obtain the distance <s> between the planes and that distance will represent the closest points in the slot.

figure 10, Boundary Plane Slot Example

It is important that your PCS be established close to the desired location where the distance should be taken. As shown in figure 10, should the PCS be outside the effective location the distance is expected, the reported result will not represent the actual distance.

figure 11, Localization of the PCS

Referring to figure 11, we have two established Part Coordinate Systems. PCS 1 is established on the base of the 2.000" gage block. PCS 2 is located 4.000" inches in the X direction from the right side of the gage block.

Two planes were measured, one representing the lower base and one on top of the gage block, The lower base plane was used to establish the XY PCS Base Plane for both PCS 1 and 2. The top plane had a AZ/X of 89.9943° and the AY/Z was 90.0000°. The intersection with the pierce point with the PCS1 Z Axis, d1, is reported at 1.9999". The reported pierce point on the Z axis of PCS2, d2 is 1.9995". By not having PCS localized to the actual measured surfaces we introduced 0.0004", d3, error!

Click here for a more detailed discussion on Projection Errors.

Tolerance of Planes is available in Cartesian / Linear format.

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