A VM17 spindle that rotates slowly but never locks before a tool change can indicate a command-interface mismatch after replacing a Magnatek drive with a Hitachi SJ700. The reported SJ700 behavior requires the JOG and forward-run inputs simultaneously; a JOG command alone may not produce the expected orientation motion.
Identify the command mismatch
The original drive completed tool changes, while the replacement SJ700 leaves the spindle turning. This isolates the first diagnostic decision to the replacement drive's input logic and configuration. The available evidence reports that the SJ700 exposes a jog function in its parameters but does not accept JOG as a standalone run command.
| Observed condition | Engineering interpretation | Check |
|---|---|---|
| Old Magnatek oriented correctly | Machine-side orientation hardware previously operated | Compare old and new drive input functions |
| SJ700 rotates but does not stop | Run-command logic or mechanical capture may be incomplete | Monitor JOG, forward-run, cylinder, and proximity-switch states |
| Clicking during slow rotation | The bearing may be passing the wheel detent without capturing it | Inspect cylinder travel and verify the orientation speed |
Understand the orientation sequence
The reported mechanism commands low-speed spindle motion while energizing an air cylinder above the spindle. The cylinder presses a bearing against a wheel containing a machined notch. When the bearing enters the notch, a proximity switch signals the controller to stop the motor, and the cylinder mechanically holds the spindle in position.
A failure at any point can leave the spindle rotating: the drive may not receive a valid run combination, the cylinder may not extend, the bearing may miss the notch, or the proximity switch may not change state. The cited cylinder, bearing, and sensor specifications came from a different machine and are not confirmed for the VM17; identify the installed parts before ordering replacements.
Correct the SJ700 input logic
- Trace the controller's orientation or jog output and confirm whether it currently reaches only the SJ700 JOG input.
- If the machine wiring confirms the reported SJ700 behavior, use an interposing relay driven by the controller's jog output. Wire separate relay contacts to command both JOG and forward run at the drive at the same time.
- Confirm that the relay drops both commands when the orientation proximity switch indicates capture and the controller ends the orientation sequence.
A reported operational workaround is to command the spindle to run before issuing orientation:
S50 M3
M19This workaround depends on the machine control accepting those commands and is not a substitute for correcting the input interface.
Verify speed, stopping, and hardware
The previous drive reportedly used a jog frequency of 1.5 Hz, while another installation achieved capture at about 1 Hz. These values are observations, not a confirmed VM17 setting. If the bearing repeatedly clicks past the notch, reduce the configured jog frequency cautiously and verify capture without assuming either value is universally correct.
A separate WJ-series installation used parameter A039 set to 03, described as “Free Run Stop,” to let the bearing fall into the slot without bouncing. Do not transfer that setting to the SJ700 without confirming that A039 has the same function on the installed drive. Verify the complete result by observing low-speed rotation, cylinder extension, bearing capture, proximity-switch transition, motor stop, and spindle retention before permitting a tool change.
FAQ
Why does my VM17 spindle keep turning during M19 after installing an SJ700?
The reported SJ700 input behavior requires JOG and forward run simultaneously. Check whether the controller supplies only JOG, then verify the drive input states during M19.
What jog frequency should I use for VM17 spindle orientation?
The evidence reports 1.5 Hz on the previous drive and about 1 Hz on another installation, but no VM17-specific value is confirmed. Reduce speed only as needed to obtain reliable bearing capture, then verify the full orientation sequence.
Can I use S50 M3 before M19 with a Hitachi SJ700?
S50 M3 before M19 is a reported workaround that provides a run command before orientation. Confirm that the machine control accepts the sequence and correct the JOG/forward-run interface for a permanent repair.
