G81: Drilling Cycle

G81 (X- Y- Z-) or (U- V- W-) R- L-

The G81 cycle is designed for drilling.

The cycle includes the following actions:

1. Preliminary movement described in the section "Canned Cycles".
2. Move the Z axis with the current feedrate to Z position.
3. The Z axis moves quickly to the return height along Z.

Example 1

Suppose the current position (X1, Y2, Z3) and the following line of G-code is executed:

G90 G98 G81 X4 Y5 Z1.5 R2.8

In the example, when the command is executed, the absolute positioning mode (G90) and the mode of returning to the initial height in Z (G98) are valid.

The following movements will take place:

1. Quick movement in the XY plane to the point (X4, Y5).
2. Fast movement along the Z axis to a point (Z2.8).
3. Moving along the Z axis at a given feedrate in (Z1.5).
4. Fast movement along the Z axis in (Z3).

Example 2

Suppose the current position (X1, Y2, Z3) and the following line of G-code is executed:

G91 G98 G81 X4 Y5 Z-0.6 R1.8 L3

In the example, when executing the command, the incremental positioning mode (G91) and the mode of returning to the initial height in Z (G98) are effective. The machine performs a drilling cycle three times. The initial position in X is 5 (= 1 + 4), the initial position in Y is 7 (= 2 + 5), the return height in Z is 4.8 (= 1.8 + 3), the target position in Z is 4.2 (= 4.8-0.6 ) The initial position in Z is 3.

During the preliminary movement, a quick movement along the Z axis to the position (X1, Y2, Z4.8) is made, since the initial height in Z is less than the return height.

The first iteration of the loop consists of 3 movements:

1. Fast movement in the XY plane in (X5, Y7).
2. Moving along the Z axis at a given feedrate in (Z4.2).
3. Fast movement along the Z axis in (X5, Y7, Z4.8).

The second iteration of the loop consists of 3 movements:

1. Fast movement in the XY plane in (X9, Y12, Z4.8).
2. Movement along the Z axis with a given feedrate in (X9, Y12, Z4.2).
3. Fast movement along the Z axis in (X9, Y12, Z4.8).

The third iteration of the cycle consists of 3 movements:

1. Fast movement in the XY plane in (X13, Y17, Z4.8).
2. Movement along the Z axis with a given feedrate in (X13, Y17, Z4.2).
3. Fast movement along the Z axis in (X13, Y17, Z4.8).

Example 3

Suppose that the current position (X0, Y0, Z0) instead of (X1, Y2, Z3), and a line of G-code is executed:

G90 G98 G81 X4 Y5 Z1.5 R2.8

Since the initial height in Z is less than the value of the parameter R, during the preliminary movement, the initial movement in Z will be performed.