Body - BOS Industry's hole opener body is forged of 4145 Heat Treat, quenched and tempered steel, and ranges in overall length of 120" up to 132". The tool meets API Specification 7 minimum material requirements for rotary drill stem elements.
Collector Box & Core Breakers - Welded to the hole opener body, the collector box, or "cross", consists of two 2-1/2" thick plates bridged by a 1x2" piece of A-36 steel, which is used for its suitability for welding. The thickness of the steel plates makes the collector box able to withstand weight and impact while rotating.
Mounts - The mounts are cast iron and register a Brinell hardness factor of 218 up to 223 with a 3,000-kg. load, which provides strength while allowing welding. The mounts are weld-beveled and machined to accommodate cutters before being welded to the cross. A hole drilled through the mount and the first plate of the collector box accommodates jets.
Cutters - Each hole opener has a set of four cutters, which are cast to the same specifications as the mounts. The cutters are machined to fit mounts and to accommodate journals and bearings. A pair of cutters is left-hand spiraled; the other pair is right-hand spiraled.
Tool Repair & Cutter Installation
Repairing Weld Cracks and Strap Marks - Minor weld cracks can be repaired easily by grinding. If cracks are more severe, a BOS Industry representative will promptly inspect and rectify the troubled area.
Strap marks and strapping material are also corrected by grinding them off; torch cutting is not recommended.
Special Notes
• All rotary-shouldered connections should be coated with thread compound in storage or during shipment.
• All rotary-shouldered connections should have thread protectors in storage or during shipment.
• Apply lubricant to all drill and tapped areas, load pins before loading cutters, tighten "lock screws" before screwing hammer jack into load pins.
• All gauge dimensions on all hole sizes have tolerance of +1/16", -1/4".
