Changing of tool is an operation only to be carried out by a Level 2 certified user or the Fabrication Lab Supervisor.
Move router to over bed (this is so if the bit drops it doesn't hit the ground)
Pair the right sized collet for the cutting Tool you have selected
Blow collet out clean with compressed air
Blow Collet nut out clean with compressed air and inspect (clean collet nut with steel wool if required).
Inspect Clamping nut surfaces on the Spindle (clean with steel wool if required and blow out clean with compressed air)
Fit collet in Collet nut with an audible click