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G43 Tool length offset
Mach3 Mach4 G-code · Mill
Applies the length offset from tool table entry H. The DRO then shows the tool tip position.
Format
G43 H [Z]
Addresses
| Address | What it does |
|---|---|
H | Tool table entry, usually same as tool number |
Z | Optional move in the same block |
How it works
Modal, length offset group. Cancel with G49.
Example program
G0 G20 G90 G54 G17 G40 G49 G80 (SAFE START, INCH)
T3 M6 (TOOL CHANGE)
S9000 M3 (SPINDLE ON)
G0 X0 Y0 (OVER THE PART)
…
T3 M6 (TOOL CHANGE)
S9000 M3 (SPINDLE ON)
G0 X0 Y0 (OVER THE PART)
…
The full 8-line example is in the app. Example is in inch. Check offsets and clearances first.
Watch out for
- Mach3 omitting H or H0 means a zero offset. The tool tip can then run into the part.
- Mach3 applies an implied G43 when you type a tool number in the T DRO, but a program still needs G43 H.
- Hobby routers often touch off Z on each tool. Then keep length offsets at zero, or do not mix both methods.
Related codes
G43 on other controls
The same number can mean something different on another control.
| Control | Meaning |
|---|---|
| Fanuc | Tool length compensation |
| Haas NGC | Tool length compensation plus |
| Mazak (EIA) | Tool length offset, plus direction |
| Okuma OSP | 3D compensation cancel |
| Mitsubishi M70 M80 | Tool length comp plus |
| Brother Speedio | Tool length offset plus |
| Fagor 8055 8065 | Tool length compensation on |
| LinuxCNC Tormach | Tool length offset on |
| Centroid CNC12 Acorn | Tool length compensation plus |
| Hurco WinMax (NC) | Tool length offset plus |
| Fadal | Tool length compensation positive |
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Open G43 in the app All Mach3 Mach4 G-codes