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Siemens SINUMERIK Controller
Program/G-code · Basic · 5 - 15 minutes
Siemens 10605 - Block thread pitch decrease too high
SINUMERIK alarm 10605 occurs when the Z-axis physically contacts the positive hardware limit switch, triggering an immediate emergency stop. This hardware interlock is activated by machine data parameter MD36100 (POS_LIMIT_SWITCH) and prevents mechanical damage to the machine structure.
10605
Siemens 10605 - Block thread pitch decrease too high
Block thread pitch decrease too high
The thread pitch decrease is causing an axis standstill in the thread block Control reaction: Correction block is reorganized. Local alarm reaction. Interface signals are set. Alarm display.
Root Cause Summary
SINUMERIK alarm 10605 occurs when the Z-axis physically contacts the positive hardware limit switch, triggering an immediate emergency stop. This hardware interlock is activated by machine data parameter MD36100 (POS_LIMIT_SWITCH) and prevents mechanical damage to the machine structure.
Safety
- Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.
Causes and Fixes
- 1
Check Active Work Offset
Press OFFSET key, navigate to Work Offset tab, verify G54-G59 Z-axis values against machine coordinate system using MD26010 (G54_X), MD26020 (G54_Y), MD26030 (G54_Z).
Use machine coordinate display (MCS) to verify actual position relative to machine zero
- 2
Verify Tool Length Compensation
Check Tool Management, verify active tool length offset T-number corresponds to correct geometry offset D-number in tool table parameters.
Excessive positive tool length values can cause virtual overtravel
- 3
Validate Program Coordinates
Review NC program for Z-axis moves, calculate total travel including work offset + tool length + programmed coordinate against MD36200 (SOFTWARE_LIMIT_PLUS_Z).
Use SINUMERIK simulation mode to trace axis movements before execution
Call a technician if:
- ·Encoder feedback errors persist
- ·Machine data parameter corruption
- ·Mechanical damage to limit switches or actuators
Prevention
- Regular verification of work offset accuracy
- Implement program simulation before execution
- Periodic limit switch function testing
- Maintain proper reference point procedures
Common Mistakes
- Ignoring software limit warnings before hardware activation
- Incorrect tool length measurement entry
- Modifying machine data without understanding coordinate relationships
- Forcing jog movement while on limit switch
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