The three codes
| Code (FANUC) | Name | What the controller does |
|---|---|---|
G43 H.. | Tool length compensation | Shifts Z by the tool length |
G43.4 H.. | Tool centre point control, type 1 | Program gives tip position + rotary angles; controller compensates |
G43.5 H.. | Tool centre point control, type 2 | Program gives tip position + tool vector (I, J, K); controller calculates angles |
All are cancelled with G49. Availability depends on the controller series and purchased options.
Why TCP matters
Without TCP, when a rotary axis moves, the tool tip swings around the pivot point. The post must calculate compensating XYZ moves using exact pivot and tool length data. With TCP, the controller does this in real time, so:
- Programs are independent of tool length (change a tool, no re-post).
- Programs are independent of exact part position relative to rotary centres (with suitable setup).
- Feedrate applies at the tool tip, giving consistent cutting conditions.
Example comparison
(Type 1 - angles)
G43.4 H7
G01 X10. Y5. Z3. A-15. C30. F1000.
(Type 2 - vectors)
G43.5 H7
G01 X10. Y5. Z3. I0.1294 J-0.2241 K0.9659 F1000.Vector values here illustrate the format; the relationship between angles and vector depends on the machine's kinematics.
Equivalents on other controllers
| Controller | TCP function |
|---|---|
| SINUMERIK | TRAORI |
| Heidenhain | M128 / FUNCTION TCPM |
| Haas | G234 (TCPC) |
| Fagor 8065/8070 | #RTCP ON |
| Mitsubishi | G43.4 / G43.5 |
G43 is for 3-axis. For simultaneous 5-axis, TCP is the professional standard.
TCP-ready post development
See our CNC post processor development service and tool length compensation.