T (Tool number)

The T parameter in G-code is a value that represents the tool selection or tool change command, which is used to specify the machine's tool or device being employed for a particular operation. This parameter can be applied to various machines and processes, such as milling, turning, or laser cutting, where multiple tools or devices may be used within a single program. The T parameter is typically followed by a tool number, which corresponds to a specific tool in the machine's tool library or carousel. It plays a significant role in managing the sequence of operations and ensuring that the correct tool is engaged for each process in a multi-tool machining setup.

To select a tool, program T..., where the number is the tool changer slot for the tool. The tool is not changed until an M6 (Tool Change) command is programmed. The T-word may appear on the same line as the M6 command or on a previous line.

It is possible to program a T word more than once before a tool change takes place, but only the last issued statement is taken into consideration. The carousel may move a lot, but only the most recent T-word will take effect at the next tool change. It is OK to

It is possible to issue T0 this means that no tool will be selected. This is useful if the spindle needs to be empty after a tool change. An error occurs if: • a negative T number is used, • a T number larger than the number of slots in the tool changer is used.