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G76 Lathe multi pass threading
LinuxCNC Tormach G-code · Lathe
Cuts a full thread in many passes from a drive line. Sets pitch, depth, infeed angle, degression, spring passes and taper.
Format
G76 P Z I J K [R] [Q] [H] [E] [L] [$]
Addresses
| Address | What it does |
|---|---|
P | Thread pitch, distance per revolution |
Z | Final Z position of the thread |
I | Thread peak offset from the drive line, negative for external |
J | First cut depth, positive |
K | Full thread depth, positive |
R | Depth degression, 1 constant depth, 2 constant area |
Q | Compound infeed angle, often 29.5 |
H | Spring passes |
E L | Taper length and where it is, L 0 none, 1 entry, 2 exit, 3 both |
How it works
Non modal.
Example program
G20 G18 G8 G90 (INCH, XZ PLANE, RADIUS MODE)
T4 M6 G43 (THREADING TOOL)
G97 S600 M3 (THREAD AT 600 RPM)
G0 X0.2 Z0.2 (DRIVE LINE AT RADIUS .200)
…
T4 M6 G43 (THREADING TOOL)
G97 S600 M3 (THREAD AT 600 RPM)
G0 X0.2 Z0.2 (DRIVE LINE AT RADIUS .200)
…
The full 7-line example is in the app. Example is in inch. Check offsets and clearances first.
Watch out for
- Start at the drive line, an X clear of the thread, and a Z ahead of the start.
- The current manual says I J K read as diameter in G7. Check on your version with a dry run.
- Needs a spindle encoder. Keep feed hold and overrides off during threading.
- R below 1 is an error.
Related codes
G76 on other controls
The same number can mean something different on another control.
| Control | Meaning |
|---|---|
| Fanuc | Fine boring cycle |
| Haas NGC | Fine boring cycle |
| Mazak (EIA) | Fine boring cycle |
| Okuma OSP | Fine boring cycle |
| Mitsubishi M70 M80 | Fine boring cycle |
| Brother Speedio | Fine boring cycle |
| Fagor 8055 8065 | Probing move while touching |
| Mach3 Mach4 | Fine boring, Mach4 |
| Centroid CNC12 Acorn | Fine boring cycle |
| Hurco WinMax (NC) | Fine boring with orient |
| Fadal | Fine boring with oriented shift |
| Swiss (Citizen Star) | Multiple pass threading cycle |
Every G-code for LinuxCNC Tormach 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 G76 in the app All LinuxCNC Tormach G-codes