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:

$$TLO = current\_tool\_position - reference\_tool\_position$$

Example

1. First tool: Probed at machine Z position -72.300 → becomes reference tool

2. Second tool: Probed at machine Z position -105.688 → current tool

3. 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

Demo of M491.1

Example

M491.1              ; Perform tool break check with default tolerance (0.1mm)
M491.1 H0.05        ; Perform tool break check with 0.05mm tolerance

M493 - 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 values

M493.1 - 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 position

M493.2 - 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 active

M493.3 - 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)

Demo of M493.3

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-30.488

M493.4 - Report Current TLO

Description

M493.4 reports the current tool length offset values to the console.

Parameters

None

Example

M493.4              ; Report current TLO values