CNC Machinist Calculator UltraHome › G-codes › Mazak (EIA) › G74
G74 Reverse tapping cycle / Z axis peck drilling cycle
Mazak (EIA) G-code · Mill, Lathe
On mills: Reverse tapping cycle
Taps a left hand thread. The spindle runs counterclockwise down and reverses at the bottom.
Format
Addresses
| Address | What it does |
|---|---|
X Y | Hole position |
Z | Hole bottom |
R | R plane |
P | Dwell at the bottom |
F | Feed, RPM times pitch in G94 |
How it works
Modal, canned cycle group. Cancel with G80.
Example program
G90 G54 G00 X1. Y1. S400 M04 (SPINDLE REVERSE)
G43 H09 Z1. M08 (LENGTH OFFSET)
G74 Z-.75 R.2 F30.77 (400 RPM TIMES .0769 PITCH)
…
The full 5-line example is in the app. Example is in inch. Check offsets and clearances first.
Watch out for
- Start the spindle with M04 before the cycle.
- Feed hold and override do not act during the tap stroke.
On lathes: Z axis peck drilling cycle
Pecks along Z on center with a short retract after each peck. Also used for face grooving when X moves are given.
Format
Addresses
| Address | What it does |
|---|---|
R | Retract after each peck |
Z | Final depth |
Q | Peck depth in 0.0001 inch, no decimal point |
P | X step for face grooving, 0.0001 inch |
F | Feed rate |
How it works
Non-modal.
Example program
G97 S1500 M03 (CONSTANT RPM)
G00 X0. Z.1 M08 (ON CENTER)
G74 R.02 (RETRACT .02)
…
The full 6-line example is in the app. Example is in inch. Check offsets and clearances first.
Watch out for
- Q and P are in 0.0001 inch with no decimal point. Q2500 is .25 inch.
- For drilling, give X0 or leave X out and start on center.
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 |
| 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 Mazak (EIA) 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 Mazak G-codes