Rockmore said its engineers saw a need for retrieval and decided to develop a new model with retrac-style cutting fins in the rear section to promote better retraction from a hole.
"After blast holes are drilled in the tunnel face with hole diameters ranging from 43-51 millimetres, certain holes in the pattern are enlarged with a typical reaming bit to 76-102mm, depending on the blast and rock formation requirements," the company explained.
With a standard reaming bit, the face designs have domes or narrow nose fronts, and are effective at enlarging a predrilled hole.
"When they are retrieved out of the hole, however, at the end of the target hole depth, they often seize up due to the loose rock debris inside the hole formation," Rockwell added.
EVP Pejman Eghdami added that, once the field support colleagues discovered the need, it worked with various drilling teams to create the retrac features for its new reaming bit.
With the new release, the fins can effectively push out rock chips trapped behind the bit when the string is pulled from the blast hole, providing more efficient reaming operations.