1748

Common Causes

• A workpiece shorter than required is chucked, so the quill over-travels before touching it (operation error)
• Tailstock initial position is too far from the workpiece, so the quill hits the overtravel limit switch before contact
• Tailstock advance command was issued with no workpiece mounted in the chuck (operation error)
• On NC tailstock machines, the workpiece-hold confirmation limit switch dropped out during advance

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code 1 = Quill over-advanced far enough to trip the over-advance confirmation limit switch; code 2 = Quill over-advanced and the in-position limit switch was OFF; code 3 = NC tailstock: quill over-advanced and the workpiece-hold confirmation limit switch turned OFF
2. 2Read the code on screen. Code 1: the over-advance confirmation limit switch actuated. Code 2: the in-position limit switch stayed OFF. Code 3 (NC tailstock): the workpiece-hold confirmation limit switch turned OFF.
3. 3Check that a workpiece is actually mounted in the chuck and that its length matches the setup; a short workpiece lets the quill run past the expected contact point.
4. 4Verify the tailstock body initial position is close enough to the workpiece that the quill reaches it before the overtravel dog; reposition the tailstock or adjust the dog position if not.
5. 5Only issue the tailstock spindle advance command after a workpiece is set in the chuck; correct the operating procedure or program sequence accordingly.
6. 6If the alarm recurs with correct setup, inspect the over-advance, in-position, and workpiece-hold confirmation limit switches and their wiring for proper actuation.