Fanuc Parameter 1860 Work ^hot^ Page

This is a full guide to Fanuc Parameter 1860, explaining what it does, why it matters, and how to set it correctly.

1. Spindle Encoder and Zero Pulse

Every modern FANUC spindle motor comes with a built-in encoder (often a pulse coder with 1024, 2048, or 4096 pulses per revolution). This encoder generates a one-per-revolution (Z) pulse that marks a reference position. However, due to mechanical tolerances in coupling the encoder to the spindle shaft, the Z-pulse rarely aligns exactly with the physical keyway or tool-change orientation required by the machine.

2. When do you need to change it?

You typically only touch this parameter during: fanuc parameter 1860 work

1. Motor Replacement: Swapping an old motor for a new one with a different encoder.
2. Scale Replacement: Replacing a linear glass scale with a different resolution model.
3. Retrofitting: Installing a new CNC control on an old machine.
4. Pitch Error Compensation Failure: If the machine consistently drifts or cannot finish the pitch error compensation cycle.

Interrelationship with Other Parameters

Parameter 1860 does not work in isolation. It is tightly coupled with:

• Parameter 1820 (CMR - Command Multiplier): This parameter scales the CNC’s internal command pulses. Together, 1820 and 1860 define the overall closed-loop gain.
• Parameter 1815 (APC, APZ): When setting the absolute position encoder, the control relies on the feedback resolution defined by parameters like 1860 to establish the machine’s position at power-up.
• Parameter 1870 (Separate Detector Pulse Count): In some advanced configurations, 1870 works in conjunction with 1860 for dual-feedback systems.

Conclusion

FANUC Parameter 1860 is a precise and powerful tool that bridges the digital command of the CNC with the analog reality of mechanical motion. While it may be overshadowed by more commonly discussed parameters, its correct configuration is the bedrock of accurate axis scaling, consistent homing, and safe operation. For any service engineer or machinist facing unexpected axis movement errors, verifying the value of Parameter 1860 against the specifications of the installed pulse coder is an essential diagnostic step. In the high-stakes world of precision machining, this single parameter ensures that a command to move one inch results in exactly one inch of movement—no more, no less. This is a full guide to Fanuc Parameter

Practical Implications for Setup and Troubleshooting

For a machine tool builder or maintenance technician, correctly configuring Parameter 1860 is a non-negotiable step during initial commissioning or after replacing a servo motor or coder.

1. Reference Point Return: An incorrect Parameter 1860 will cause the axis to return to a different physical location each time a reference return (home) is performed. The grid shift defined by Parameter 1850 relies on the accurate pulse count from Parameter 1860 to establish a consistent zero point.
2. Following Error (Deviation): If the value is set too low, the CNC will command a high speed but receive few feedback pulses, leading to a large following error alarm (e.g., ALARM 410 or 411 - "SERVO ALARM: EXCESS ERROR").
3. Rapid Traverse Mismatch: The axis will not move at the programmed rapid traverse rate. For instance, commanding G00 X100. may result in the table moving only 50mm.

3. Parameter Details

| Parameter Number | Data Type | Unit | Valid Range | | :--- | :--- | :--- | :--- | | 1860 | Word Integer (2-byte) | Percentage (%) | 0 – 100 (or higher depending on specific Fanuc Series/Option) | Motor Replacement: Swapping an old motor for a

• Typical Setting: 100 (Disables override increases; locks feed at 100%).
• Default Setting: Often set to 150 or 200 by machine tool builders (MTB).

6. Step-by-Step: How to Change Parameter 1860

⚠️ WARNING: Changing parameters can affect machine safety. Always write down the original value before changing it.

1. Enter MDI Mode: Set the mode selector to MDI.
2. Enable Parameter Write:
   • Press the OFFSET/SETTING button on the keypad.
   • Navigate to the SETTING soft key.
   • Find the line labeled "Parameter Write".
   • Change it from 0 to 1.
   • The machine will likely alarm (usually Alarm 100 or 000) asking you to turn off the parameter switch. You can ignore this alarm while editing parameters.
3. Search for the Parameter:
   • Press the SYSTEM button on the keypad.
   • Type 1860 on the numeric keypad.
   • Press the [NO. SRH] (Number Search) soft key.
4. Edit the Value:
   • Cursor down to the parameter number 1860.
   • Type the new value (e.g., 100).
   • Press INPUT.
5. Lock Parameter Write:
   • Go back to OFFSET/SETTING -> SETTING.
   • Change "Parameter Write" back to 0.
6. Reset: Press the RESET button to clear the alarm.