NCT Group NCT 990T - Manual (Page 76)

7.2.1 Work Zero Point Offset Measurement
76
Work Zero Point Offset Measurement, if Tool Length Equals to Tool Overhang
If tool length equals to the X-
and Z-direction tool overhang
(because for example tool offset
measuring was executed on an
external measuring device) the
work offset (work zero point)
must always be measured. This
can be done by taking a cut with
a tool previously measured, in
X- and Z-direction on the
workpiece in the spindle, than
measuring the diameter and
length of workpiece on the place
where the cut was taken and en-
tering the sizes to control. The
control takes the tool overhang
into account automatically when
calculating the work zero point
offsets, if prior thereto the tool
offset group containing its size
was selected.
The offset value can be calculated from the following equation:
M
x
= x – x
c
– x
0
M
z
= z – z
c
– z
0
where
– M
x
, M
z
: value of work zero point offset
– x, z: reference position of tool holder in machine coordinate system (excluding length offset)
– x
c
, z
c
: X- and Z-direction tool length offset
– x
0
, z
0
: data entered to coordinate Z in the course of measuring, the measured size of the
workpiece.
L Note:
Values x and z of the above equation differ to position seen on position display G53, if
tool length has been called (Tnnmm). In values "x, z" the called length offset is never
taken into account. Therefore before measuring it is useful to delete tool length by
means of command Tnn00, however this only makes position display more under-
standable.