Method for connecting a casing tube (4) to a drill bit (1) in which method an annular groove (6) that circulates around the outer track is formed at the outer track of the bit (1) and in order to connect the casing tube (4) to the bit (1 ) at its front edge, one uses a drill shoe, such as a connection ring (2), as an aid which drill shoe can be installed around the bit (1) and which connection ring is attached both to the mentioned annular groove (6) and on the other hand to the mentioned casing tube (4) in which case at the first stage of the installation a chopped ring element (3) is installed into the groove (6) located at the outer track of the bit (1) at least partly. At the second stage the connection ring (2) is pushed around the bit (1) so far that the ring element (3) existing in the groove (6) becomes strained at the same time into the groove (5) existing at the inner surface of the connection ring (2) in which case when the connection ring (2) is being moved, the ring element (3) follows in the groove (5) along the connection ring and slides in the groove (6) of the bit ( 1 ) in such a way that its movement to the deepest point of the groove (6) is prohibited by adding a stopper (7), (8) to the structure which stopper restricts the movement of the connection ring (2).