Fanuc spindle alarm 67 means a reference position return command was issued for the slave axis while spindle EGB (Electronic Gear Box) mode was active. EGB electronically locks a slave axis to the spindle's rotation — the function behind gear hobbing, thread grinding and similar synchronized processes (G81 engages it, G80 releases it). While the slave axis is locked to the spindle, it cannot go off and perform a reference return — the two demands are contradictory, and the control refuses with AL-67. This is a programming/sequence alarm, not a hardware fault — nothing needs replacing.
The fix — straight from the manual
Turn EGB mode off (G80) before commanding the reference position return. The correct order in the program or MDI:
- G80 — cancel the EGB synchronization (spindle and slave axis decouple).
- Command the reference return for the slave axis.
- Re-engage with G81 afterwards if the process continues.
Where it actually bites
- Program flow: a subprogram or macro that assumes EGB is off (a homing cycle, a tool-change macro that references the axis) called from within a G81 section — audit the program flow around the alarm point; the offending reference-return command is usually buried in a called macro rather than the visible program.
- Operator/MDI: an operator issuing a manual reference return after an interruption (E-stop, reset mid-cycle) while the control is still logically in EGB mode. After interruptions, cancel EGB (G80) as part of the recovery procedure, then home.
- Restart/recovery sequences: if AL-67 appears repeatedly at the same recovery step, build G80 into the restart macro so the machine cleans up its own state — the durable fix.
Tip: AL-67 is the control protecting your synchronization, not misbehaving. On hobbing/grinding machines, make ‘G80 before homing, G81 after’ part of the standard recovery instructions posted at the machine — it turns a recurring morning alarm into a non-event. If the alarm appears with NO reference-return anywhere in your program, check the ladder/macros the builder supplied: some builders issue homing internally on mode changes, and a retrofit or parameter change can expose that sequence.
Diagnosis checklist
- Confirm the machine uses spindle EGB (hobbing/synchronized grinding) and note the exact block where AL-67 fires.
- Find the reference-return command — in the program, a called macro, or an operator action.
- Insert/perform G80 before it; re-engage G81 after.
- Recurring at recovery → add G80 to the restart/recovery macro.
Related guides
- Fanuc spindle alarm 36 (error counter overflow — position-mode sequencing)
- Setting the Fanuc reference position / zero return
- Fanuc αi drive alarms — PSM, SVM & SPM codes explained
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