1747

Common Causes

• Tailstock quill in-position confirmation limit switch is out of adjustment
• Sizing limit switch and overtravel limit switch not synchronized so they fail to come ON together at workpiece contact
• Quill mechanically obstructed or not actually advancing to the workpiece
• Faulty or sticking in-position confirmation limit switch

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code 2 = In-position answer signal missing within 60 seconds of the tailstock advance command; code 3 = In-position answer signal missing within the time set by parameter after the advance command
2. 2Read the code on screen: Code 2 means the answer never came within the fixed 60-second window; Code 3 means it did not come within the time set in the parameter — both point to the same confirmation switch circuit.
3. 3Command M56 again and watch the quill physically advance to the workpiece; if it stalls or stops short, clear the obstruction or correct the tailstock setup before touching switches.
4. 4Advance the quill until it touches the workpiece and check whether the in-position confirmation LS actually changes state at that point.
5. 5Adjust the sizing limit switch and overtravel limit switch so both come ON at the same moment the advancing quill contacts the workpiece, per the manual's corrective action.
6. 6If adjustment cannot make the switch trip reliably, replace the in-position confirmation limit switch and retest with M56.