Core drill with detachable end portion

A core drill comprising:

• at least an end portion and a drill bit portion, where the end portion and the drill bit portion are joinable in a watertight fashion, and where a sealing element is provided in a space between the end portion and the drill bit portion, wherein the sealing element is arranged such that it is being compressed in a sealing fashion when the end portion and the drill bit portion are joined, and where the end portion and the drill bit portion are locked together with a joining element, comprising a screw portion arranged in the drill bit portion and joining part arranged in the end portion, where the screw portion is arranged such that the screw portion can be screwed such that screw portion moves in the radial direction of the core drill between a locking and a non-locking position, and where the screw portion and/or the joining part comprise at least one surface that, in a cross section extending parallel to and through the center axis of the core drill, extends at an angle to the radial direction of the core drill, and where this angled surface is arranged such that when the screw portion moves in essentially the radial direction of the drill, the end portion and the drill bit portion are forced to move towards each other along the direction of the axis of the core drill.