Mills Machine has 40 years of experience behind our full line of Horizontal Roller Cone Hole Openers (Back Reamers). Available in sizes from 6″ to 120″ (150mm to 3 meters), Mills Machine can manufacture larger Hole Openers to meet any specific design. These ruggedly constructed units are made from 4142 heat-treated alloy steel and feature the roller rock bit cutters of your choice. Horizontal Hole Openers are available in single, double, or multiple stages with a regular or flat-plate design. The front and back necks can be as long or as short as you desire, featuring breakouts, flats, or lugs as needed. Circulation can be standard or reverse for horizontal or raised bore drilling. Circulation can also be fluid or air depending on your rig capabilities. Cutter styles available include Steel Tooth or TCI button bits in New, Retip or Rerun condition with Regular or Sealed Journal Bearings. We also offer any thread size and an unlimited number of custom designs.