HEIDENHAIN TNC 426 (280 476) - Manual (Page 209)

182 7 Programming: Miscellaneous functions
7.
4 Miscellaneous F
unctions f
o
r Cont
our
ing Beha
vior
Insert rounding arc between straight lines: M112
Compatibility
For reasons of compatibility, the M112 function is still available.
However, to define the tolerance for fast contour milling,
HEIDENHAIN recommends the use of the TOLERANCE cycle, see
“Special Cycles,” page 337.
Machining small contour steps: M97
Standard behavior
The TNC inserts a transition arc at outside corners. If the contour steps
are very small, however, the tool would damage the contour.
In such cases the TNC interrupts program run and generates the error
message “Tool radius too large.”
Behavior with M97
The TNC calculates the intersection of the contour elements—as at
inside corners—and moves the tool over this point.
Program M97 in the same block as the outside corner.
Effect
M97 is effective only in the blocks in which it is programmed.
Example NC blocks
A corner machined with M97 will not be completely
finished. You may wish to rework the contour with a
smaller tool.
X
Y
X
Y
S
16
17
15 14
13
S
5 TOOL DEF L ... R+20 Large tool radius
...
13 L X ... Y ... R.. F .. M97 Move to contour point 13
14 L IY–0.5 .... R .. F.. Machine small contour step 13 to 14
15 L IX+100 ... Move to contour point 15
16 L IY+0.5 ... R .. F.. M97 Machine small contour step 15 to 16
17 L X .. Y ... Move to contour point 17