In the world of CNC machining, precision is everything. A misalignment of just 0.001 inches can scrap a part costing thousands of dollars. Among the hundreds of system parameters that control a Fanuc CNC controller, Parameter 1860 often stands out as both a powerful tool and a potential hazard.
: It stores the absolute position data for each controlled axis. Absolute Encoders : This parameter works in conjunction with Parameter 1815 (specifically the fanuc parameter 1860 full
Here is the interesting "hidden" feature regarding this parameter that many machinists overlook: Fanuc Parameter 1860 Full: The Ultimate Guide to
Note: In newer FANUC controls (31i-B, 0i-F), parameter 1860 is often replaced or augmented by parameter 1865 (grid check tolerance), but 1860 remains active for legacy mode or specific axis setups. Check belt/pulley alignment (if semi-direct drive)
0: The reference position is not established. The machine does not know its absolute zero, and you will likely see a "Need ZRN" (Zero Return) alarm or a 300-series absolute pulse coder alarm.
| Machine Type | Rigidity | Typical 1860 Range (ms) | | :--- | :--- | :--- | | Small VMC (BT30) | High | 30–60 | | Large VMC (BT40/BT50) | Medium | 60–120 | | Heavy-duty lathe (X-axis) | Medium | 80–150 | | Gantry mill (heavy slide) | Low | 120–250 | | High-speed machining center | Very High | 10–40 |
Servo Tuning: If the Position Gain (P1825) is too low, the axis won't have enough "stiffness" to stay in place.