Description and Improvements

The diamond core drill requires a rotary motion and circulating fluid.  The 1860's saw not only the invention of the diamond drill but also numerous patents for pioneer rotary drilling machines although the fluid circulating rotary method could be traced to an 1844 English patent by Robert Beart of Godmanchester.  Rotary drilling came into considerable use in the United States via fluid circulating rotary drilling rigs in Corsicana, Texas in 1894-1900 and in 1901 at Spindletop and thereafter.

In the 1920's and 30's the single tube core barrel was gradually replaced by double tube core barrels.  The inner tube or barrel held the core by core catchers and pivoted dogs and also protected it.  The double tube core barrel for diamond drilling was patented in 1892 by M.G. Bullock, but its use in oil well drilling was slow to happen (Brantly, 1971) .

The diamond core heads changed greatly in the number of borts placed in the sintered matrix in the 1940's to present.  One rib of a diamond bit now holds many more stones than an entire bit of earlier decades.  Note the illustration of a 1965 diamond core bit.

A Christensen diamond core bit ca. 1965.  Christensen Diamond Products Co. advertized with the phrase, Diamonds Mean, "Less cost per foot".