I've been studying industrial CNC controls and one thing I've seen that's pretty much universal on big iron is a spindle load meter. I'm curious whether something of the sort might be useful on my X2 as I don't recall ever seeing one and a search of the forum here didn't reveal much of anything.
I'm assuming that the straightforward way to implement something like this would be to measure the current drawn by the motor using an ammeter. I'm not looking for an ultra-precise measurement, more like "No Sweat," "Getting Up There," and "Maxed Out."
What I'm envisioning is to calibrate things based on the difference between current draw with no load (i.e. cutting air) and with the spindle loaded to the point just before RPM starts to fall. You could then look at where you are on the gap between the two to get a sense of how much headroom you have.
Assuming this would give an accurate indication of % spindle capacity, I also don't know whether it would be useful in the sense that general rigidity is often the limiting factor long before spindle torque is. Even then I'd be curious whether there's enough consistency between torque and rigidity limits--i.e. maybe 50% of spindle torque is where you're going to start running into rigidity problems when milling, while you can push a twist drill very close to 100% and be fine.
Has anyone ever tested current draw and RPM on their mill to see if there's any useful information to be gained here?