Resolving Hyperturn 100 HS Spindle Power Oscillation

After adding SPCOF at the correct point in the transfer sequence, the main spindle can return to ordinary speed control without cyclic no-load power swings or continued motion after reset. Follow the command path from the CNC program to the active spindle-control state: SPCON was issued during the transfer, but that state remained active because no matching SPCOF was executed.

Where does the spindle command path stop?

The request begins in the part program. The CNC interpreter processes the transfer sequence, issues SPCON, and passes the resulting mode request into the spindle-control functions. Those functions continue regulating the main spindle until the program explicitly changes the state.

This is a retained-state problem, not a command that automatically expires when the mechanical handoff finishes. The first commissioning check is therefore program-state continuity: every path that can execute SPCON must later reach SPCOF.

What physical checks come before editing the program?

Layer one first. Cyclic power modulation can also result from binding, eccentric loading, an incompletely released workholding device, or residual contact between the two spindle systems. Separate those conditions from a control-state fault before changing logic.

1. Stop automatic operation and place the machine in the approved service condition for inspection.
2. Check that the transfer mechanics have completed their commanded movement and that no spindle, chuck, workpiece, or tooling component remains in unintended contact.
3. Inspect the workpiece position and clamping state. Look for eccentric seating or a handoff condition that could impose a once-per-revolution load.
4. With tooling clear, observe whether the main-spindle power indication still rises and falls while the spindle rotates without cutting.
5. Record whether the disturbance begins specifically after the counter-spindle-to-main-spindle transfer.

The reported machine showed extreme power variation during unloaded rotation after the transfer. That timing directs the next check toward the executed control sequence. Proceed only after confirming that the oscillation is not produced by mechanical contact or an actual cutting load.

Which program state causes the power fluctuation?

Search the transfer routine, called subprograms, conditional branches, and recovery paths for SPCON and SPCOF. The relevant comparison is not merely whether both tokens exist somewhere in the program; it is whether the active execution path pairs them in the correct order.

An active spindle relationship can make the controller continually correct position or speed error. If the transfer has mechanically ended but the control mode has not, small angular or load differences can drive alternating torque commands. The load meter then climbs and falls even though no tool is engaged. On the affected setup, pressing reset made the main spindle shake, and it stopped only after the motors were switched off. After the motors were switched back on, the machine operated normally because the power transition cleared the problematic operating condition.

The decisive check is an execution trace or single-block observation showing SPCON executed without a later SPCOF before ordinary main-spindle running began.

How should the transfer sequence be corrected?

Add the missing state-release command to the normal completion path. Also inspect every alternate exit, because correcting only the most common branch leaves the same fault available during an interrupted, rejected, or conditional transfer.

1. Identify the block where SPCON becomes active.
2. Trace the successful handoff through all calls, jumps, and conditions.
3. Identify the first point where the temporary spindle relationship is no longer required.
4. Insert or restore SPCOF at that point, before ordinary independent main-spindle operation.
5. Check every alternate branch that can leave the transfer routine after SPCON. Route it through the required shutdown logic or add the corresponding SPCOF.
6. Review reset and restart handling so an interrupted cycle cannot resume under an unknown spindle state.

Do not place SPCOF earlier merely to suppress the symptom. Releasing a transfer-related control mode before the mechanical handoff reaches its valid release point can create a different sequence error. Confirm the command position against the machine program structure and its documented transfer procedure. The proof for this stage is a dry trace in which every path from SPCON reaches SPCOF at the intended transition.

How do you test the correction without masking the fault?

A motor power cycle restored normal operation in the reported case, but it did not correct the program. Test from a known initial state, then reproduce the complete command path that previously failed.

1. Save the corrected program under the site’s normal change-control process.
2. Start from a known machine state with the work area clear and the spindle unloaded.
3. Run the transfer sequence at the approved commissioning mode and observe the blocks containing SPCON and SPCOF.
4. Confirm that SPCOF executes after the handoff and before normal main-spindle running.
5. Command the main spindle under the same no-tool-engagement condition that previously produced the power fluctuation.
6. Watch the power indication for repeated rises and falls synchronized with spindle rotation.
7. Repeat the sequence through each conditional program path that can execute the transfer.

A passing result requires stable unloaded rotation, no once-per-revolution power surge, and repeatable execution of SPCOF. Do not count a test performed only after cycling motor power as proof; that action can clear the symptom without proving that the program now releases the state.

Which recurring pitfalls can recreate the problem?

The final end-to-end test is consecutive counter-spindle-to-main-spindle transfers without a motor power cycle: verify that SPCON is followed by SPCOF, the unloaded main spindle rotates smoothly, its power indication remains stable, and a normal stop completes without shaking.

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