Fanuc Parameter 1860 Full →

| Problem | Cause | |---------|-------| | Alarm PS0030 or PS0031 | 1860 set too high → reference point signal missed due to overshoot | | Inconsistent reference position (drift every cycle) | Speed too high for deceleration zone length (dog/switch timing mismatch) | | Long cycle time | 1860 set unnecessarily low (e.g., 100 mm/min on a large VMC) | | Machine overshoots reference point | 1860 > rapid rate (not allowed; parameter clamped internally) |

The relationship between time constant (T) and acceleration (a) is:

a (mm/s²) = Vc / T

Where:

Example:

Real-world adjustment: Most machines will not run a 10 ms 1860 due to mechanical resonance. Multiply by 3–5x for safety (e.g., 40–60 ms).

When setting Parameter 1850 (grid shift), P1860 must be larger than the correction amount. Example: fanuc parameter 1860 full

| Machine Type | Typical P1860 (detection units) | Comment | |-----------------------|---------------------------------|---------------------------------| | Machining Center (VMC)| 1000 – 3000 | Standard tolerance range | | Lathe (Turning) | 500 – 1500 | Shorter axis travel | | Large Gantry Router | 5000 – 8000 | High inertia, longer decel zone | | Grinder (precision) | 200 – 500 | Tight tolerance, slow speeds |

Unit conversion: If parameter 1820 = 100 (0.1 µm/unit), then 1000 units = 0.1 mm.

This is the most serious consequence. You calculated the shift in the wrong direction. Always test with a dry run and the rapid override turned to 25% or lower. | Problem | Cause | |---------|-------| | Alarm

This is not an error, but a reminder. Set PWE back to 0.

A: Older controls (Fanuc 6, 10, 11, 12, 15) use different parameter numbering. For example, on Fanuc 15, the reference shift might be Parameter 700+ (axis-specific). Check your yellow Fanuc manual.

| Parameter | Function | Interaction | |-----------|----------|-------------| | 1420 | Rapid traverse (G00) | Must be ≥ 1860 in value | | 1850 | Grid shift | Fine reference point offset; 1860 affects grid capture reliability | | 3001 | Reference point deceleration signal (dog length) | If dog is short, 1860 must be lowered | | 1826 | Position coder 1-revolution signal check speed | Must be higher than 1860 to detect reference mark | The relationship between time constant (T) and acceleration