CNC Machinist Calculator UltraHome › G-codes › Haas NGC › G74
G74 Reverse tapping cycle / End face grooving and peck drilling cycle
Haas NGC G-code · Mill, Lathe
On mills: Reverse tapping cycle
Taps a left hand thread. The spindle runs CCW into the hole and reverses out. Works like G84 with the opposite direction.
Format
Addresses
| Address | What it does |
|---|---|
X Y | Hole position |
Z | Hole bottom |
R | R plane |
F | Feed rate, RPM times pitch in G94, or pitch in G95 |
S | Spindle speed |
J | Retract speed multiple, J2 retracts twice as fast |
L | Number of holes for repeats in G91 |
How it works
Modal, canned cycle group 09. Cancel with G80.
Example program
G90 G54 G00 X1. Y1. S500 (HOLE POSITION AND SPEED)
G43 H06 Z1. M08 (APPROACH)
G74 G99 Z-.5 R.1 F25. (25 IPM EQUALS 500 RPM TIMES .05 PITCH)
…
The full 5-line example is in the app. Example is in inch. Check offsets and clearances first.
Watch out for
- The control runs the spindle in the correct direction for the cycle.
- Feed must match RPM times pitch exactly or the tap breaks.
On lathes: End face grooving and peck drilling cycle
Pecks in Z for face grooves or center drilling. With X and I it steps over and pecks again for a wide face groove. Peck retract comes from Setting 22.
Format
Addresses
| Address | What it does |
|---|---|
Z | Absolute depth of the pecks |
W | Incremental depth of the pecks |
K | Peck depth in Z |
X | Diameter of the furthest groove pass |
U | Incremental X to the furthest pass |
I | X step between groove passes, diameter |
D | X clearance shift before returning, rarely used |
F | Feed rate |
How it works
Non-modal, group 00.
Example program
G97 S600 M03 (FIXED RPM)
G00 G54 X2.5 Z.1 M08 (START AT OUTER GROOVE DIAMETER)
G74 X2. Z-.25 I.2 K.05 F.003 (FACE GROOVE 2.5 TO 2.0 DIAMETER)
…
The full 5-line example is in the app. Example is in inch. Check offsets and clearances first.
Watch out for
- Do not use D when there is a wall on both sides of the groove. The shift will break the tool.
- If the X distance is not a multiple of I, the last step is smaller.
- For a plain drilled hole on center, G74 without X gives a simple peck drill.
Related codes
G74 on other controls
The same number can mean something different on another control.
| Control | Meaning |
|---|---|
| Fanuc | Left hand 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 |
| Mach3 Mach4 | Left hand tapping, Mach4 |
| 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 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 G74 in the app All Haas NGC G-codes