The drill bit then can be used to drill a selected one of several diameters, according to the number of additional cutting edges.

The present invention relates to method and apparatus for drilling a large diameter hole in the ground.

A daughter cylinder having an inner diameter equal to the outer diameter of a drill for forming a recess in the bone underneath the implant is arranged in the mother cylinder.

The ground drilling device can drill a hole with a long length (deep) and a relatively large diameter.

The drill bit then can be used to drill a selected one of several diameters, according to the number of additional cutting edges.

The drill (10) is further adapted to drill a hole having a diameter of about 0,5 mm.

The bottomhole assembly includes a formation displacement member adapted to drill a borehole having a diameter greater than the diameter of the guide assembly.

They can drill holes with casing having diameter of up to one meter (40 inches).

The operator lowers a string of drill pipe (25) into the conductor to drill a first smaller diameter well at the bottom of the conductor.

The design is compact and can be used to drill wellbores as small as about 2 1/2' in diameter, or even smaller.

An underreamer for well drilling comprises pivotally extendible roller cutters that extend slightly beyond the diameter of the pilot drill bit but are retained in their retracted position by the casing.

Due to the non-kick back operation, you can drill holes of up to 200 mm in diameter free hand

Provided is boring equipment having a large diameter cutter head and being capable of an efficient boring even if an object to be bored is hard ground or the like.

As a result of the invention the number and/or size of the ground engaging tools (25) are not a function of the bore diameter to be drilled.

For high temperature measurements, a hole (depth of which is at least 6 times the diameter) can be drilled into the object.