T-SLOT cutting - CNC Machining

I don't understand how the arbor helps If you're going straight down, won't the arbor collide with the walls of the slot you're cutting?

Groove Milling for small and medium bore diameters GM Slot offers indexable inserts for internal and external grooving and chamfering applications with a

indexable t slot cutter I don't like slot drilling, my tiny hobbymat mill doesn't like it I have found that overlapping chain drillling end the end milling the slot

indexable t slot milling cutter 4 cutting edges per indexable insert; For machining radial grooves and T-slots in machine beds; With internal coolant for reliable chip evacuation by