Update cnc.md

Author: MateoVanDamme

docs/infra/cnc.md

@@ -3,7 +3,8 @@
 The space has a 3 axis CNC machine based on the High-Z S-720 from [CNC-STEP](https://www.cnc-step.com/high-z-s-720-cnc-router-720-x-420-x-110-mm-trapezium-screws/). To use the machine either 1T, Elvis, Teus or Sander should be present. 
 
 ## Safety
-The machine has two E-stops (emergency stops). One is located on the x-axis gantry and another one on the electronics box. When pressed they cut the voltage to the spindle, motors and controller board. ``TODO: FACT CHECK``. 
+The machine has two E-stops (emergency stops). One is located on the x-axis gantry and another one on the electronics box. When pressed they cut the voltage to the spindle, motors and controller board. 
+Extra informatino about implementation: It cuts off the controller board which also deprives the steppers of current. The spindle circuit is cut off using a seperate relay.  
 
 ![E-stop gantry](./images/cnc_estop.jpg)