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G33 Thread cutting with constant lead
Siemens 840D 828D G-code · Lathe
Cuts a thread with the axis feed locked to the spindle. K is the lead along Z, I along X for face threads. SF= shifts the start angle for multi start threads.
Format
G33 Z K [SF=] or G33 X I [SF=]
Addresses
| Address | What it does |
|---|---|
Z | Thread end point in Z |
K | Lead along Z in mm per rev |
X | End point in X for face or taper threads |
I | Lead along X for face threads |
SF= | Start angle offset in degrees for multi start threads |
How it works
Modal, G group 1 (motion).
Example program
G97 S600 M3 ; FIXED RPM FOR THREADING
G0 X19 Z5 ; START, 5 MM RUN IN
G33 Z-30 K1.5 SF=0 ; FIRST PASS
G0 X22 ; RETRACT
…
G0 X19 Z5 ; START, 5 MM RUN IN
G33 Z-30 K1.5 SF=0 ; FIRST PASS
G0 X22 ; RETRACT
…
The full 8-line example is in the app. Example is in inch. Check offsets and clearances first.
Watch out for
- Start far enough in front of the part to let the axis reach speed, or the first threads have the wrong lead.
- Keep spindle override constant during the cut. Feed override has no effect in G33.
- Use G97 so the rpm does not change between passes.
Related codes
G33 on other controls
The same number can mean something different on another control.
| Control | Meaning |
|---|---|
| Fanuc | Thread cutting, constant lead |
| Okuma OSP | Fixed thread cycle, longitudinal |
| Fagor 8055 8065 | Electronic threading |
| LinuxCNC Tormach | Spindle synchronized motion |
Every G-code for Siemens 840D 828D 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 G33 in the app All Siemens 840D 828D G-codes