Tip: If you will make it a HABIT after loading your gcode file into Mach3, to navigate to the Toolpath Screen, and click on Simulate Program Run you can get a fairly accurate estimate of time until the various tool changes (IF your CAM software has added comments in the gcode such as Roughing, Finishing, etc. at the location of the M3's) by watching the elapsed time in the Simulation text box. You have to watch the Status field at the bottom of the screen closely, and when you see the message change from Roughing Cut, to Finishing Cut IMMEDIATELY glance up at the Simulator text box to read the elapsed (estimated) time. It's not an exact method, but it will get you in the ballpark of estimating when the toolchanges will occurr. Just be sure to read the elapsed time IMMEDIATELY after the message changes in the Status field, because it continues to run the Simulation (and the elapsed time is still flying by). As I said, it's not exact. But it will get you within a couple of minutes of WHEN you need to be there. I still like the idea of a DRO box which gives you a count down to next tool change - Additionally, it would be nice if Mach3 also included a box which lists line numbers of all tool changes. In case of inacurate Re-Zero of the Z axis happens during a tool change (for quick reference of where to set next line to Run From Here, after subsequently correcting the Z Zero). For those of us not yet equipped with digital probes for setting the Z Zero......