CALYPSO: True Position of a Slot with MMC - Formulas

Written by Jason Jonassen

How to Evaluate True Position of a Slot with MMC In CALYPSO 

Example: 

Measure:

• Top Plane (Datum A) 

• Center Circle (Datum B) 

• Symmetry Point in Left Slot (Datum C) 

• Left side of slot to evaluate as a line or plane 

• Right side of slot to evaluate as a line or plane

Create Constructions: 

CONSTRUCTION>PERPENDICULAR between Left and Right side of slot.

• FEATURES>POINT.  Open the point and choose NOMINAL DEFINITION>RECALL.  Select the Perpendicular from above. 

• FEATURES>CIRCLE.  Open the circle and choose NOMINAL DEFINITION>THEORETICAL FEATURE.   

         In the X ACTUAL field of the circle, right click and choose formula.  Enter the formula getActual(“Point1”).x assuming the constructed point is named “Point1”. 

         In the Y ACTUAL field, right click and choose formula.  Enter the formula getActual(“Point1”).y assuming the constructed point is named “Point1”. 

         In the Z ACTUAL field, right click and choose formula.  Enter the formula getActual(“Point1”).z assuming the constructed point is named “Point1”. 

         In the Diameter ACTUAL field, right click and choose formula.  Enter the formula getActual(“Perpendicular1”).len assuming the constructed perpendicular is called “Perpendicular1”. 

         Enter appropriate NOMINALS for the slot center.   Note that the nominals do not need to be perfect – the true position nominals will take care of that. 

Create Characteristic: 

• FORM AND LOCATION>TRUE POSITION 

• Enter the Theoretical Circle as the Feature.  Enter the top plane, center circle, and slot symmetry into the window as the Datums. 

• Click the SPECIAL BUTTON in the True Position window and Rotate about the Z axis the basic dimension angle of 108°. 

• In the True Position window, change the SHAPE OF ZONE to ONLY Y. 

• Edit Y basic dimension to Zero if it is not Zero already. 

• Change RFS to MMC in the dropdown for the Circle Feature and ensure the characteristic nominals and tolerances are correct for the Circle diameter. 

• Enter your True Position tolerance from the Print. 

Understand Report: 

• Below is what is a graphic describing what is set up in the True Position Characteristic. 

• Below is the CALYPSO Custom Printout with Additional Position Result turned on. 

• This Report indicates that the Slot is in Tolerance, but shifted to the “right” by 0.0828mm in the rotated coordinate system.  Notice that the tolerance WITH BONUS, 0.1728mm, is shown in the “Lower Tol.” Column.