Delta Tau GEO BRICK LV User Manual

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Turbo PMAC User Manual 
306
 
Writing and Executing Motion Programs 
Until a surface-normal vector is declared explicitly with 3D compensation active, no actual compensation 
will occur.  A tool-orientation vector must also be declared for compensation to work on anything other 
than a ball-nose cutter. 
Turning Off 3D Compensation 
3D cutter compensation is turned off by the buffered motion program command CC0, just as for 2D 
compensation.  Compensation will be removed over the next LINEAR or CIRCLE mode move after 
compensation has been turned off. 
Declaring the Surface-Normal Vector 
The direction of the surface-normal vector is determined by the NX{data}NY{data}, and 
NZ{data} components declared in a motion program line.  The absolute magnitude of these components 
does not matter, but the relative magnitudes define the direction.  The direction must be from the surface 
into the tool. 
Generally, all three components should be declared together.  If only one or two components are declared 
on a program line, the remaining component(s) are left at their old value(s), which could lead to 
unpredictable results.  If it is desired that a component value be changed to zero, it should be declared 
explicitly as zero. 
Note that the coordinates of the surface-normal vector must be expressed in the machine coordinates.  If 
the part is on a rotating table, these coordinates will not in general be the same as the original part 
coordinates from the part design – the vector must be rotated into machine coordinates before sending to 
Turbo PMAC. 
The surface-normal vector affects the compensation for the move on the same line of the motion program, 
and all subsequent moves until another surface-normal vector is declared.  In usual practice, a surface-
normal vector is declared for each move, affecting that move alone. 
Declaring the Tool-Orientation Vector 
If the orientation of the cutting tool can change during the compensation, as in five-axis machining, the 
orientation for purposes of compensation is declared by means of a tool-orientation vector.  (If the 
orientation is constant, as in three-axis machining, the orientation is usually declared by the normal vector 
to the plane of compensation, although the tool-orientation vector may be used.) 
The direction of the tool-orientation vector is determined by the TX{data}TY{data}, and 
TZ{data} components declared in a motion program line.  The absolute magnitude of these components 
does not matter, but the relative magnitudes define the direction.  The direction sense of the tool-
orientation vector is not important; it can be from base to tip, or from tip to base 
Generally, all three components should be declared together.  If only one or two components are declared 
on a program line, the remaining components are left at their old values, which could lead to 
unpredictable results.  If it is desired that a component value be changed to zero, it should be declared 
explicitly as zero. 
Note that the coordinates of the surface-normal vector must be expressed in the machine coordinates.  If 
the part is on a rotating table, these coordinates in general will not be the same as the original part 
coordinates from the part design. 
The tool-orientation vector affects the compensation for the move on the same line of the motion 
program, and all subsequent moves until another tool-orientation vector is declared.  In usual practice, a 
tool-orientation vector is declared for each move, affecting that move alone. 
Note that the tool-orientation vector declared here does not command motion; it merely tells the 
compensation algorithm the angular orientation that has been commanded of the tool.  Typically the 
motion for the tool angle has been commanded with A, B, and/or C-axis commands, often processed 
through an inverse-kinematic subroutine on Turbo PMAC.