I pretty much have my 3-axis CNC mill conversion complete and I am now looking to add all the nice-to-have goodies. I run my spindle via a VFD that talks over a serial connection to Mach 3. I was thinking that it would be really neat to set up a macro pump or brain in Mach 3 that read the spindle load from the VFD and automatically slowed down the feed rate via the feed rate override DRO if it sensed that the spindle motor was being overloaded and could potentially stall. What do people think? I thought it might be cool to do full closed-loop control to optimize spindle loading but I quickly realized that it would be a very bad idea to allow the control to increase the feed rate over-ride based solely on spindle load (especially for small tools for which you could never reasonable use the full spindle power).