CNC Machinist Calculator UltraHome › G-codes › Mach3 Mach4 › G74
G74 Left hand tapping, Mach4
Mach3 Mach4 G-code · Mill
Mach4. Taps a left hand thread with a floating holder. The spindle must already run in reverse with M4.
Format
G74 X Y Z R [L] F
Addresses
| Address | What it does |
|---|---|
X Y | Hole position |
Z | Thread depth |
R | Retract plane |
F | Feed, spindle speed times pitch in G94 |
How it works
Modal, canned cycle group. Cancel with G80.
Example program
G0 G20 G90 G54 G17 G40 G49 G80 (SAFE START, INCH)
T7 M6 (.250-20 LH TAP)
S500 M4 (SPINDLE REVERSE)
G0 X1.0 Y-1.0 (HOLE)
…
T7 M6 (.250-20 LH TAP)
S500 M4 (SPINDLE REVERSE)
G0 X1.0 Y-1.0 (HOLE)
…
The full 8-line example is in the app. Example is in inch. Check offsets and clearances first.
Watch out for
- Start the spindle with M4 before the cycle.
- Overrides and feed hold are locked out during the cycle.
- Not in the Mach3 G code table.
Related codes
G74 on other controls
The same number can mean something different on another control.
| Control | Meaning |
|---|---|
| Fanuc | Left hand tapping cycle |
| Haas NGC | Reverse tapping cycle |
| Mazak (EIA) | Reverse tapping cycle |
| Okuma OSP | Reverse tapping cycle |
| Mitsubishi M70 M80 | Reverse tapping cycle |
| Brother Speedio | Left hand tapping cycle |
| Siemens 840D 828D | Reference point approach |
| Fagor 8055 8065 | Home search |
| LinuxCNC Tormach | Left hand tapping cycle |
| Centroid CNC12 Acorn | Left hand tapping cycle |
| Hurco WinMax (NC) | Left hand tap (ISNC) or single quadrant arc (BNC) |
| Fadal | Left hand tap |
| Swiss (Citizen Star) | Face peck drilling and grooving cycle |
Every G-code for Mach3 Mach4 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 G74 in the app All Mach3 Mach4 G-codes