1) For spatial circular interpolation, the path to the end point along an arc
can be obtained by specifying the midpoint as well as the end point.
The movement can be divided into the following two blocks: a block
from the start point to the midpoint and a block from the midpoint to
the end point. Therefore, during single–block operation, the nozzle
does not move at the first start, but moves from the start point to the
end point at the second start.
2) When spatial circular interpolation is specified continuously, the end
point of the previous block is used as the start point of the next block.
(Always specify the midpoint and end point because the midpoint of
the previous block is not used as the start point of the next block.)
3) The G12 command is treated as linear interpolation if it cannot create
an arc because:
(a) Neither a midpoint block nor an end–point block has been
(b)The start point, midpoint, and end point are on a straight line, or
(c) Two or more of the start point, midpoint, and end point are
4) The G12 command cannot specify axis movement for any axis other
than the first to fifth axes, because alarm 4025 occurs.
5) G12 cannot be issued during coordinate system rotation (G84).
6) G12 cannot be issued during three–dimensional coordinate transform
7) G12 cannot be issued during cutter compensation. It must be issued
with cutter compensation canceled.