Selecting The Preset - HEIDENHAIN TNC 620 User Manual

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Fundamentals | NC fundamentals

Selecting the preset

A production drawing specifies a certain form element of the
workpiece (usually a corner) as the absolute reference point (datum).
When setting the preset, first align the workpiece along the machine
axes, and move the tool to a known position in each axis relative
to the workpiece. For each position, set the display of the control
either to zero or to a known position value. You thereby assign the
workpiece to the reference system that is applicable for the control's
display or your NC program.
If the production drawing is dimensioned in relative reference points,
simply use the coordinate transformation cycles.
Further information: User's Manual for Programming of Machining
Cycles
If the production drawing is not dimensioned for NC programming,
then select a position or corner of the workpiece as a reference point
from which the dimensions of the remaining workpiece positions
can be determined.
A particularly convenient way of setting the presets is with a 3-D
touch probe from HEIDENHAIN.
Further information: User's Manual for Setup, Testing and Running
NC Programs
Example
The workpiece drawing shows holes (1 to 4), whose dimensions are
shown relative to an absolute preset with the coordinates X=0 Y=0.
The coordinates of holes 5 to 7 refer to the relative preset with the
absolute coordinates X=450 Y=750. A Datum shift allows you to
temporarily shift the datum to the position X = 450, Y = 750 in order
for you to program the holes (5 to 7) without further calculations.
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HEIDENHAIN | TNC 620 | Klartext Programming User's Manual | 01/2022