I am using MeshCAM. I could change the setup template for Mach3 and add the G4 statement there.
I would prefer to do that because I can more easily document (for others) what I did - right in the Gcode file.

I would also like to improve this delay by having a pop-up info box with instructions to adjust the spindle speed then press OK to continue. I don't know if that is possible.

The ShopBot that I used at TechShop Detroit uses it own language instead of Gcode. They added a PAUSE command and the ability to create a pop-up info box.

Now I have an Industrial CNC machine which is straight Gcode and don't know how to get the ShopBot features.

As for the spindle spin-up rate, I don't seem to have the ability to change that. That is one of the deficiencies of the ICNC machine. I'll be posting another thread asking how to connect Mach3 to the FVController so that I can program the spindel speed that I want in the Gcode.

Till then, I need to put up instructions on how to manually set the speed and wait for it to reach the target RPM, or in this case the target frequency.

Thanks for the G4 info. I'll start there.

Let me know if you have any ideas on the pop-up info box idea.

JA