The document describes various G-code boring cycles used in CNC machining. G85 is a basic boring cycle that rapidly positions the tool to the hole location and reference point before feeding to the programmed depth and back. G86 is for rough boring while G76 is for finishing with a programmed shift amount. G88 includes a dwell at depth for manual operations before retracting, while G89 dwells and retracts automatically. Each cycle uses X,Y,Z,R coordinates and F feed rate along with options like K repeats or P dwell time.

1. Boring cycle

2. What is boring?
• Boring is the process of enlarging pre existing hole.

3. G85 Description
• Rapid motion to hole position
• Rapid motion to R point
• Feed rate motion to Z depth
• Feed rate motion back to R level

4. G85 boring cycle
• G85 X...Y…Z…R…F…K…
• Hole position in X & Y axis.
• R = Reference position.
• Z = Final depth.
• F = Feed rate Spec.
• K = No. of Repeats.

5. G86 and G76 Description
• G86
• After positioning along the X–
and Y–axes, rapid traverse is
performed to point R.
• Drilling is performed from
point R to point Z.
• When the spindle is stopped at
the bottom of the hole, the
tool is retracted in rapid
traverse.
• G76
• When the bottom of the hole
has been reached, the spindle
is stopped at the fixed rotation
position, and the tool is moved
in the direction opposite to the
tool tip and retracted. This
ensures that the machined
surface is not damaged and
enables precise and efficient
boring to be performed.

6. G86 roughing G76 finishing cycle
• G86 X...Y…Z…R…F…K…
• G76 X...Y…Z…R…P…Q…F…K…
• Hole position in X & Y axis.
• Q = Amount of shift for boring
• R = Reference position.
• Z = Final depth.
• F = Feed rate Spec.
• K = No. of Repeats.
• P = Dwell time

7. G88 Description
• Rapid motion to hole position
• Rapid motion to R point
• Feed rate motion to Z depth
• Dwell at the depth in milliseconds
• Spindle rotation stops(CNC operator switch to
manual operation mode and perform a manual task
then switch back to prog.)
• Rapid retract to safety position
• Spindle rotation ON

8. G88 boring cycle
• G88 X...Y…Z…R…P…F…K…
• Hole position in X & Y axis.
• R = Reference position.
• Z = Final depth.
• F = Feed rate Spec.
• K = No. of Repeats.
• P = Dwell time

9. G89 Description
• Rapid motion to hole position
• Rapid motion to R point
• Feed rate motion to Z depth
• Dwell at the depth in milliseconds
• Feed rate motion back to safety position

10. G88 boring cycle
• G89 X...Y…Z…R…P…F…K…
• Hole position in X & Y axis.
• R = Reference position.
• Z = Final depth.
• F = Feed rate Spec.
• K = No. of Repeats.
• P = Dwell time