View Full Version : Cutting Flatout! - monitoring and optimising the current drawn by the spindle/router

Mon 17 August 2009, 22:24
Something I came across in my travels in and out of CNC workshops is the load feedback loop. Can we or does anyone incorporate this into MM use.

This feedback loop measures the load on a motor by how much current is being drawn, for 2 functions.

1:Used to determine the maximum cutting load possible for the motor rating (eg full load current (spindle or router and possibly steppers for feed rates) This means you can start to maximise your cutting speed and reduce part completion time.

2: Monitor bit quality. For repetitive cuts a history of load (amps) can be mapped and applied to the live cut, as the bit starts to wear and blunt then the current draw for the path increases and the software can flag a warning or stop. Additionally if a spike (up = tool jam, down= tool break) occurs then the machine can auto shutdown.

I intend to hook up a VFD and want to look at incorporating this principle so if someone is already doing it here, I'm happy to follow the leader.