Inner corner selection(G238)of TRC

Using inner corner selection means that the TRC should be selected at an inner corner of a closed contour.

In connection with the inner corner selection the following designations are used:

• Selection block: Linear motion block which starts at the point of selection
• First motion block: Motion block that starts at the end of the selection block, this block is also the second motion block after selection of TRC
• Last motion block: last motion block is the motion block before the deselection of TRC appears

Programming example

In contours like a star the TRC should be selected in a pointed inner corner.

%musterstern.nc
N1 G74 X1Y2Z3
N2 G17 G00 X0Y0Z0 G90
N4 F10000
(Display of the contour)
N100 G01 X0 Y100 
N110 X-20 Y20
N120 X-100 Y0
N130 X-20 Y-20
N140 X0 Y-100
N150 X20 Y-20
N160 X100 Y0
N170 X20 Y20
N180 G01 X0 Y100
N200 G00 X0Y0
(Display of the path of tool)
N210 G238 (Activation of inner corner selection)
N220 V.G.WZR = 10 (Determine the radius of tool)
N230 G41 (Selection of TRC at the left hand side of the contour)
N240 G01 X0 Y100 (Selection block)
N310 X-20 Y20
N320 X-100 Y0
N330 X-20 Y-20
N340 X0 Y-100
N350 X20 Y-20
N360 X100 Y0
N370 X20 Y20
N380 G01 X0 Y100
N390 G40 (Deselection of TRC)
N400 G00 X0Y0
N999 M30

Annotation:

The command of selection G41 or G42 take place at point P1, point P2 is the endpoint of the first linear block. This first linear block is the selection block. This point has to be simultaneous also the endpoint of the last motion block before deselection to get a closed contour.

The outer (blue) represented process is the programmed contour, the inner (red) is the path of the tool.

Remark:

After the programmed G40 of the deselection of TRC no monitoring takes place on contour injury with the following movement block.