Haas 802 - NEGATIVE R AND C VALUES NOT ALLOWED | Haas CNC Alarm
Alarm 802 fires when the way lubrication reservoir float switch detects oil level at or below the minimum threshold. The NGC control continuously monitors this input to prevent axis motion when insufficient lubrication could damage precision ground ways and linear bearings.
HaasSystemBasic10-20 minutes
802
Haas 802 - NEGATIVE R AND C VALUES NOT ALLOWED | Haas CNC Alarm
NEGATIVE R AND C VALUES NOT ALLOWED
This alarm is triggered during G02 or G03 circular interpolation programming when negative values are entered for the radius (R) or center coordinates (I, J, K or C values in some contexts). The control rejects the command because the geometry calculator cannot process negative radius values, which would define an invalid arc. The program halts at the offending line and will not execute until corrected.
Root Cause Summary
Alarm 802 fires when the way lubrication reservoir float switch detects oil level at or below the minimum threshold. The NGC control continuously monitors this input to prevent axis motion when insufficient lubrication could damage precision ground ways and linear bearings.
Safety
Add oil soon
Causes and Fixes
1
Check Physical Oil Level
Visually inspect the way lube reservoir tank located on the machine. Check oil level against the minimum mark on the sight gauge.
Use only Haas-approved way oil (typically ISO 68 slideway oil)
2
Refill Reservoir
Add approved way oil through the fill port until level reaches the maximum mark on the sight gauge. Do not overfill.
Fill slowly to prevent air bubbles and allow float switch to settle properly
3
Clear Alarm and Test
Press RESET to clear alarm 802. Verify float switch operation by observing level in diagnostics or performing a manual lube cycle test.
Check parameter 800 (Lube Timer) to ensure proper lubrication intervals
1
Verify Oil Level vs Switch Status
Check actual oil level in reservoir. If adequate but alarm persists, suspect float switch malfunction.
Float switches typically fail in the 'low' position due to contamination or magnetic coupling failure
2
Test Float Switch Operation
Access DIAGNOSTICS > INPUTS and monitor the way lube level input while manually moving the float (if accessible). Input should change state.
Disconnect power before accessing electrical connections
3
Replace Float Switch
If switch fails to operate correctly, replace with Haas part number specific to your machine model. Verify proper wiring connections.
Clean reservoir thoroughly before installing new switch to prevent premature failure
1
Inspect Wiring Connections
Check all connections from float switch to the main control cabinet. Look for loose terminals, corrosion, or damaged wire insulation.
Always disconnect power and follow LOTO procedures before inspecting electrical connections
2
Test Circuit Continuity
Use multimeter to verify continuity through the float switch circuit. Check for proper voltage levels at the control input.
Typical float switches operate on 24VDC - verify voltage matches control requirements
3
Repair or Replace Wiring
Repair any damaged connections or replace faulty wiring using appropriate gauge wire and connectors per Haas specifications.
Use marine-grade connectors in areas exposed to coolant or oil mist
1
Check for External Leaks
Inspect all way surfaces, fittings, and tubing for oil leaks. Look for oil accumulation on machine base or floor.
Use UV dye in way oil to help identify small leaks under UV light
2
Verify Lubrication Parameters
Check parameter 800 (Lube Timer) and related lube cycle parameters. Verify settings match machine specifications and operating conditions.
Typical lube intervals range from 8-30 minutes depending on machine usage
3
Test Lube Pump Operation
Manually activate lubrication system and verify proper pump operation and distribution to all way surfaces. Check for over-pumping.
Excessive lubrication can attract debris and cause way cover damage
1
Verify Input Module Status
Access DIAGNOSTICS > INPUTS and check all input module functions. Look for other input-related alarms or erratic behavior.
Input module failures often affect multiple inputs simultaneously
2
Test with Known Good Signal
Temporarily connect a known good switch or jumper to the lube level input to verify control response and isolate the problem.
Only qualified technicians should modify control wiring
3
Replace Input Module
If input module is confirmed faulty, replace with genuine Haas replacement part and verify proper installation and configuration.
Document all parameter settings before replacing control modules
DIY Feasiblehigh confidence
Call a technician if:
·Input module replacement required
·Persistent alarm after all troubleshooting
·Multiple related system failures
Prevention
Check way lube level weekly during routine maintenance
