T-word in lathe canned cycles

[sinha_nsit]

In G71, 72 or 73, there is a provision for specifying a T-word also in the second block (e.g., T01). What is its significance? Does it change the tool before executing the canned cycle? If yes, then what offset number is used?

[dcoupar]

It might be used to activate a different offset, i.e. T0101 (in the 2nd G71 line) for the G71 cycle, then T0121 for the finishing cycle (within the finished shape definition). Other than that, it seems useless.

[sinha_nsit]

Thanks for the reply. What you have said appears to be sensible. We cannot change the tool when the turret is very close to the workpiece because of a possibility of interference. But, a new offset number can be, of course, selected. We do not get such information from the manuals.

In fact, I believe that T-word can be provided with all motion related G-codes (such as G01 etc.), with the same purpose.