And the last step using a special tool called a collar bearing. " In order to piercing (a bearing) 50 cm thick reinforced concrete walls. Hole size 25 cm (10 ") by punching many holes in the long 45cm (18") so that the channel is wide enough to get into the room.
Finally, using a special tool called "neck bearing" on drilling (neck bearing) thick reinforced concrete walls 50cm. Diameter 25cm (10 ") well was drilled several holes long. 45cm (18 ") hole wide enough to get into the room.
And finally the use of special tools called "coring machine". In the drilling coring) reinforced concrete thick wall (50cm hole size 25cm (10. ") by punching each other many long hole 45cm (18. ") in order to obtain a channel wide enough to come into the room.