Abstract: A method is disclosed for surveying drill holes with a drilling arrangement and borehole survey assembly. The method can include providing a drill tool having at least one drill rod and a drill bit assembly, and providing a borehole survey tool having a sensor) for measuring a borehole. In the method a drill tool having a central flushing channel for conducting flushing fluid to the drill bit assembly is used, and the borehole survey tool is arranged in the central flushing channel so that flushing fluid can flow in the central flushing channel past the borehole survey tool.

Abstract: A bit assembly for a drilling apparatus working by impact and rotation or merely by rotation, and comprising a pilot bit (1) drilling the hole centre and in connection with the pilot bit a ring bit (2) is arranged to drill the outer circle of the hole and, further, between pilot bit and ring bit surfaces are arranged to transmit impacts and/or rotary motion from the pilot bit to the ring bit, and the bit assembly also including an arrangement for pulling protection tube into the hole on drilling. In the bit assembly between ring bit (2) and pilot bit (1) at least an arrangement transmitting rotation is jointly fitted in the ring bit shirt portion (5) by forming the rear edge of the shirt portion seen in the drilling direction to comprise surfaces with different directions, which with one of their portion (4) can transmit rotary motion force to the ring bit (2) and with their adjacent part (3) force to pull said ring bit off the hole.

Abstract: A drill bit, the frame of which comprises a front section with protrusions. A set of first rear teeth is arranged at the front section, preferably at the rear part of the protrusions. The set of first rear teeth broadens a drilled hole when the drill is reversed.

Abstract: A method for mounting hard metal buttons in a drill bit and a drill bit. In the method, a hole (4) is worked into a drill (1) before the drill bit is tempered. Subsequently, a hard metal button (3a) surrounded by brazing material is positioned into the hole (4) of the drill bit (1). The assembly is positioned into a tempering space, in which the brazing material spreads around the hard metal button (3a) into a space between the walls of the hole (4) and the hard metal button (3a) under the influence of heat. When the drill bit (1) is cooled after this, the brazing material (5) solidifies, and simultaneously, the body portion (2) of the drill bit (1) having a higher thermal expansion coefficient presses the hard metal button (3a) through the brazing material (5).