Wegener also noted that the continents move up and down to maintain equilibrium in a process called isostasy. As an example he cited the sinking of Northern Hemisphere lands under the weight of continental ice sheets in the last ice age, and their rise since the ice melted some 10,000 years ago.
Drill that is fitted with a Pipe provides effective connection to the rig surface equipment or application with the bit and the bottom hole assembly for the purpose of pumping the Drill fluid to the bit.
Refer to a technical publication for the exact measurements for hole size. For example, if you want to use a 1/4-20 screw then you must use a #7 drill bit. Your set of taps may also state the appropriate hole size to use with each tap. tap cuts threads on the inside of a hole, to accept a machine screw or bolt. Taps can also be used to restore an internal thread that has been damaged or to cut a new, larger thread in the case of severe damage or stripping. Ad.