Direct/indirect selection (G41/G42) of TRC

When TRC is selected directly or indirectly, an approach block is generated in the selected compensation plane with the next motion block in the NC program.

When TRC is selected, G138 selects an alternative approach strategy (direct selection of TRC) besides the standard approach strategy (indirect selection of TRC).

The figures below show all the possible approach blocks for the permitted contour transitions. Two NC blocks NC10 and NC20 are illustrated for the 3 relevant contour transition angles.