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Okuma OSP Controller
System · Intermediate
Okuma OSP Alarm A 8505 - Tow-along steady rest clamp/unclamp
The control is monitoring the tow-along steady rest clamp and unclamp confirmation switches and found an impossible or unsafe state: both confirmations ON or OFF together for 6 seconds or more, the unclamp signal lost while ZA is moving with the steady rest attached, or the steady rest unclamped while XA is not at its plus variable limit position. This means the steady rest clamp state cannot be trusted, so axis motion is stopped to protect the workpiece and steady rest.
8505
Okuma OSP Alarm A 8505 - Tow-along steady rest clamp/unclamp
Tow-along steady rest clamp/unclamp
The control is monitoring the tow-along steady rest clamp and unclamp confirmation switches and found an impossible or unsafe state: both confirmations ON or OFF together for 6 seconds or more, the unclamp signal lost while ZA is moving with the steady rest attached, or the steady rest unclamped while XA is not at its plus variable limit position. This means the steady rest clamp state cannot be trusted, so axis motion is stopped to protect the workpiece and steady rest.
Common Causes
- Clamp or unclamp confirmation limit switch / proximity switch out of adjustment so both read ON or both read OFF
- Unclamp confirmation switch dropping out (loose actuator, wiring, or switch) while ZA travels with the steady rest
- Steady rest left unclamped while XA is away from the plus variable limit position
- Faulty clamp/unclamp confirmation proximity switch
Troubleshooting Steps
- 1Read the code number shown with the alarm: code 1 = Outside manual/manual-interruption mode, clamp and unclamp confirmation signals were both ON or both OFF continuously for 6 s or more; code 2 = Steady rest unclamp confirmation signal went OFF while the ZA axis was moving with the steady rest; code 3 = Steady rest is unclamped while XA is not at the plus variable limit position; confirmation input pattern matches code 2
- 2Read the code on the alarm screen. Code 1: the clamp and unclamp confirmation signals were both ON or both OFF for 6 s or more outside manual/manual-interruption mode. Code 2: the unclamp confirmation went OFF during ZA-axis movement with the steady rest. Code 3: the steady rest is unclamped while XA is not at the plus variable limit position.
- 3For code 3, move XA to the plus variable limit position and clamp the steady rest, then verify the clamp confirmation input turns ON and the unclamp input turns OFF.
- 4Watch the clamp and unclamp confirmation inputs on the I/O monitor while operating the steady rest clamp/unclamp; a healthy setup shows exactly one of the two ON in each state.
- 5If both read ON or both OFF, check the adjustment of the clamp/unclamp limit switches or proximity switches and re-gap or reposition the actuators so each switch changes state cleanly.
- 6For code 2, inspect the unclamp confirmation switch wiring and connector for a loose connection that vibrates open during ZA travel, and verify the switch stays made through the full stroke.
- 7If the alarm returns after switch adjustment and wiring checks, record the alarm number, code and object and contact Okuma service.
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