G77 Back bore cycle

Haas NGC G-code · Mill

Orients the spindle and shifts the tool, rapids through the bore, shifts back, then bores upward to cut a counterbore on the back side.

Verify on your machine. This entry could not be fully checked against the maker manual. Check your machine manual before you run it.

Format

G77 X Y Z R [Q] [I J] F

Addresses

Address	What it does
`X Y`	Hole position
`Z`	Z position to cut to on the back side
`R`	Rapid position below the part where back boring starts
`Q`	Shift amount, direction from Setting 27
`I J`	Shift amount along X or Y when Q is not used
`F`	Feed rate

How it works

Modal, canned cycle group 09. Cancel with G80.

Example program

T9 M06 (BACK BORING BAR)
G90 G54 G00 X0. Y0. S800 M03 (HOLE CENTER)
G43 H09 Z1. M08 (APPROACH)
G77 Z-.75 R-1.1 Q.1 F3. (BACK BORE FROM Z-1.1 UP TO Z-.75)
…

The full 5-line example is in the app. Example is in inch. Check offsets and clearances first.

Watch out for

Check the shift clears the bore on the way through. A wrong shift crashes the tool.
Prove it out with single block and rapid override low.

Related codes

G76 · G80

G77 on other controls

The same number can mean something different on another control.

Control	Meaning
Okuma OSP	Tapping compound cycle
Brother Speedio	Tapping cycle with pitch input

Every G-code for Haas NGC in your pocket. The app has the full example programs, search by number or shop word, a line decoder and calculators for tapping, threading and drilling.

Open G77 in the app All Haas NGC G-codes

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