I know that Mach examines the entire g code file upon opening into Mach3 to generate the toolpath. It would be great, if a field were added on the main program window which lists all tool change line numbers. This would be a great convenience, in the event of a broken bit (so that after changing the bit, and re-zero of the Z one could return to the tool change and set line number for Run From Here).
Seems like every time this has happened, I FAILED to record the line number during tool changes to know where to Set Next Line at within the program.
Even if this info could be recorded into the History file, at least this would provide a method of determining tool change line number locations OTHER than manually editing the file, and doing a search in order to find them. Since Mach has no way of sensing when a cutter bit breaks, by "going back" in the g code to the last tool change which occurred, I have found this method to yield the best results in saving the work piece (without having to completely start over a multi-hour cut).

YOu could set up Mach3 to do that . I think it has already been done a while back. You set up the M6 macros to WRITE to a history file. The data would include the filename line number and tool number. It would record programs WHEN you wanted to run a BIG ONE by using a LED to indicate when  you wanted it to run OR just bypass the operation.

(;-) TP

OR you could have Mach3 write the last line# for the tool change to an unused DRO on the settings screen.

(;-) TP