The introduce of the 34" iadc 637 hdd rock reamer bit
size:34"
Applicable formations:medium hard with high compressive strength and high abrasivemess,such as limestone,dolomite,sandstone and chert,etc.
There are three stages:
1.The first stage is to drill a small diameter pilot hole.
2.The second stage is to enlarge the hole with a  larger diameter cutting tool called an HDD Reamers,    Rock Reamer or Hole Opener.
3.The thirdstage is inserting the casing pipe or other product into the enlarged hole.