What command moves the spindle at maximum speed in CNC?
TonZaMaking
In most mainstream CNC machines (e.g., HAAS, Fanuc, Siemens, Mazak, etc.), the command to move the spindle at maximum speed is typically:
👉 S[MaxRPM] M3 or S[MaxRPM] M4
Where:
Ssets the spindle speed in RPM.M3starts the spindle in the clockwise direction.M4starts the spindle in the counterclockwise direction.
💡 How to move the spindle at the machine’s maximum allowable speed:
Most machines have a built-in max spindle speed limit set in their parameters (e.g., 8000, 12000, 15000, or 24000 RPM). If you want to always run at that machine-defined maximum without hardcoding a number, do the following:
✅ For Fanuc, Haas, and most G-code-based systems:
Example:
🔧 If you’re unsure of the exact max speed, check the machine manual or look for spindle speed limits in your machine’s parameter/settings page.
Brand-specific notes:
| Brand | Max Speed Command |
|---|---|
| Fanuc | G50 S[Max], then S[Max] M3 |
| HAAS | S[Max] M3 directly; spindle override applies |
| Siemens | Uses similar commands but may use cycles or ShopMill |
| Mazak | Uses Mazatrol (conversational), but G-code mode supports S[Max] M3 |
| Heidenhain | SPINDLE RPM MAX set in setup, then M3 to run |
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Nailed it.