Tool Offset Management
Tool Length Offset (TLO) System
During normal usage, the Tool Length Offset (TLO) is measured using the tool setter on the Carvera bed. The machine doesn't actually know the absolute height of the tool setter - it only knows that the probe triggers consistently when tools touch it. In order to support the ability to change tools the machine maintains knowledge of two tool positions, the current tool and the reference tool. This is needed to maintain consistency in the workspace between different tool lengths.
When the very first tool is probed, the Z height in Machine Coordinate Space (MCS) is recorded as the reference tool position. This tool becomes the "reference tool" that all other tools will be measured against.
Any subsequent tools that are probed afterwards update the current tool position. The TLO is then calculated as the difference between these two positions:
Example
First tool: Probed at machine Z position -72.300 → becomes reference tool
Second tool: Probed at machine Z position -105.688 → current tool
TLO calculation: -105.688 - (-72.300) = -33.388
M491.1 - Tool Break Test
Description
M491.1 performs a tool break check by calibrating the current tool and comparing its length to a previously stored tool length offset (TLO). If the difference exceeds the specified tolerance, it indicates potential tool breakage and halts the machine.
Parameters
H: Tolerance value for break detection (optional, defaults to 0.1mm)
Must be >= 0.02mm
If set too small, the command will halt with an error
Example
M491.1 ; Perform tool break check with default tolerance (0.1mm)
M491.1 H0.05 ; Perform tool break check with 0.05mm toleranceM493 - Tool Length Offset (TLO) Management
Description
M493 manages tool length offset (TLO) settings for the current tool. It can set tool offsets, change tools, and report TLO values.
Parameters
Subcode 0/1: Set tool offset from last probe position
Subcode 2: Set new tool number
T: Tool number (required)
Subcode 3: Set current tool offset manually
Z: Tool length value (optional)
H: Offset above Z0 (optional)
Subcode 4: Report current TLO values
Example
M493 ; Set tool offset from last probe
M493.2 T1 ; Set tool 1 as active
M493.3 Z10.5 ; Set tool length to 10.5mm
M493.3 H2.0 ; Set TLO from current position with 2mm offset
M493.4 ; Report current TLO valuesM493.1 - Set Tool Offset (Same as M493)
Description
M493.1 sets the tool offset from the last probe position. This is identical to M493 with subcode 0 or 1.
Parameters
None
Example
M493.1 ; Set tool offset from last probe positionM493.2 - Set New Tool
Description
M493.2 sets a new tool as the active tool and updates the system accordingly.
Parameters
T: Tool number (required)
Example
M493.2 T5 ; Set tool 5 as activeM493.3 - Set Current Tool Offset Manually
Description
M493.3 sets the current tool offset manually using either a Z value or an H offset from the current position.
Parameters
Z: Tool length value (optional)
H: Offset above Z0 (optional)
Example
M493.3 Z-15.2 ; Set tool length offset to 15.2mm
M493.3 H3.0 ; Set TLO from current position with 3mm offset
; Adding 2.9mm length to the current tool
M493.4 ; returns current tool offset [-105.688], reference tool offset [-72.300]
; tool offset is cur_tool_mz - ref_tool_mz or -105.688 - (-72.300) = -33.387
; increasing it by 2.9mm -33.387 + 2.9 = -30.488
M493.3 Z-30.488M493.4 - Report Current TLO
Description
M493.4 reports the current tool length offset values to the console.
Parameters
None
Example
M493.4 ; Report current TLO valuesLast updated