Troubleshooting Mori Seiki NZ2500 Rigid Tapping Sync

At S250 and F1.5 in feed-per-revolution mode, the intended axial feed is 250 rev/min × 1.5 mm/rev = 375 mm/min. The commanded path from an intended R5. plane to Z-30.Instead, the Z-axis advances while spindle speed remains effectively zero, so the control is not executing a valid spindle-axis synchronized cycle. This is timing and kinematics, not cutting load.

Failed substitutions and their limits

Replacing M329 with M29 does not fix a cycle selected for the wrong axis, spindle, or control option. Likewise, changing G84 to G84.2 only helps when the machine builder defines that cycle for the required tapping orientation and active path.

Changing G99 to G95 is not the answer on this installation because G99 is the identified feed-per-revolution mode. The feed mode controls the pitch relationship after synchronization exists; it does not select a spindle or enable rigid tapping.

G303 also failed to create spindle motion. That separates the fault from a simple missing synchronization request. Setting R to zero merely changes the malformed motion: it removes the Y move but produces an X move to X22. at the bottom. It does not correct the cycle geometry.

G28 H0 is another installation-specific mismatch because the machine does not accept it. Commands such as M46, M69, M329, and axis letters used with return commands must be verified in the Mori Seiki programming documentation for the exact control and path. Similar-looking controls can assign different machine functions to the same M-code.

Cycle geometry revealed by axis motion

The number that matters is the axis associated with the retract plane. The program intends R5. to describe a Z-axis tapping approach, yet the machine moves to Y-5.. That is a strong diagnostic: the control is parsing the block, but the selected cycle context does not map its drilling axis and retract word to the intended Z direction.

G18 normally establishes the X-Z plane on a lathe, but a multitasking machine can also apply path, turret, spindle, live-tool, and builder-specific canned-cycle rules. The active plane alone therefore cannot prove that G84 means axial rigid tapping on the selected path. The X move seen with R0 further shows that changing numeric values cannot repair the modal or cycle-selection mismatch.

The small spindle movement at the end is not proof of rigid synchronization. A valid rigid-tapping cycle must establish an angular master, coordinate Z travel to spindle position, reverse at depth, and coordinate the withdrawal. Motion only after the feed stroke points instead to a delayed command, a cycle exit action, or movement of a spindle that was not assigned as the cycle master.

Command-state decision table

Diagnostic isolation sequence

1. Retract the tool clear of the work and use single-block operation for the test. Watch commanded spindle speed, actual spindle speed, active path, and axis positions together.
2. Command the selected spindle in an ordinary, non-canned-cycle test using the machine-approved spindle selection and rotation commands. If it does not rotate, resolve the spindle assignment, interlock, or path selection before testing rigid tapping.
3. Confirm which spindle the active turret or channel controls. On a machine with multiple spindle resources, a speed word can be accepted without addressing the spindle expected by the tapping cycle.
4. Open the option, parameter, or diagnostic screen and check whether rigid tapping is installed and enabled for this spindle/path combination. Do not change undocumented option or parameter bits; an incorrect builder parameter can produce hazardous axis or spindle behavior.
5. Use the control's cycle table to identify the axial Z tapping cycle, its required plane, feed mode, spindle-selection state, and rigid-mode command. Check G84, G84.2, M29, and M329 only against that table rather than treating them as interchangeable.
6. Check the definitions of M46 and M69. Retain them only when their documented functions are required for the selected spindle and path.
7. Run a tool-clear test and verify which axis responds to the R word before allowing motion near the part. If R still drives Y, stop; the cycle or plane context remains wrong.

Correction procedure

1. Select the correct machining path, turret, and spindle using the machine-builder sequence for the MSX-850 III control.
2. Establish the documented plane and axial tapping cycle for a thread along Z. The required cycle may be G84 or G84.2; the observed behavior cannot identify which definition this machine uses.
3. Activate rigid tapping with the exact builder-defined command, if a separate activation command is required. Use neither M29 nor M329 until its definition is confirmed for this control.
4. Keep G99 when the cycle documentation specifies feed per revolution, then program the required 1.5 mm/rev lead as F1.5.
5. Build a minimal tool-clear test containing only verified spindle/path selection, plane, speed, rigid-mode, and tapping-cycle commands. Add coolant, returns, and other machine functions only after synchronized motion passes.
6. If the rigid-tapping option is absent or disabled, correct programming cannot create electronic spindle-Z gearing. Arrange option verification or activation through official Mori Seiki support.

Verification and recurring pitfalls

Verify the correction from the control displays before cutting. Actual spindle speed must leave zero, Z must advance in the intended direction, the R value must act along the documented drilling axis, and the spindle must reverse as Z withdraws. For F1.5, measured axial travel divided by measured spindle revolutions should equal 1.5 mm/rev within the machine's positioning and display resolution.

Run the first material test with a suitable test piece and inspect the thread with the specified gauge. A correct-looking Z trajectory is insufficient if the wrong spindle feedback channel supplies the master position; that fault can damage the tap during reversal.

Recurring mistakes include copying codes between similar controls, treating every rigid-tap M-code as universal, using R-value changes to hide an axis-selection error, and editing option parameters without the builder documentation. A program that worked on a Mitsubishi CELOS-controlled machine is a reference for intent, not a verified code map for the MSX-850 III.

FAQ