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10 Ft T38 Round Threaded Extension Drill Rod for Top Hammer Drilling:
1. Function: An Extension Drill Rod (or extension steel) is used to lengthen the drill string in percussive drilling.
2. Drilling Method: Top Hammer Drilling: This means the percussive hammer (which generates the impact energy to break rock) is located at the top of the drill string, at the drilling rig itself. The hammer strikes the top of the drill string, sending shock waves down the rods to the drill bit at the bottom.
3. Thread Type: T38 (R38):
T38: This is a specific, standardized tapered thread profile widely used in top hammer drilling equipment.
Commonly Called R38: While technically T38 is the correct designation according to standards like ISO 10208, it’s very frequently referred to as R38 (R for “Rod”) in the industry. They mean the same thing.
Features:The taper creates a tight, self-locking seal when the threads are fully engaged, crucial for efficiently transmitting both impact energy and rotation. It also helps prevent loosening during drilling and reduces thread wear.
Compatibility: Rods, drill bits, adapters, and shank adapters must all share the same thread type (T38/R38) to connect properly.
4. Design: Round:
Refers to the external shape of the rod body. It’s a solid cylindrical steel bar.
Round rods are the standard for top hammer drilling. They provide excellent strength for impact transmission and allow for efficient rotation.
(Contrast with hexagonal rods sometimes used in specific handheld or very light rig applications).
5. Length: 10 Ft (Feet):
Specifies the nominal length of the rod itself, measured from thread shoulder to thread shoulder.
Approximately 3 meters: 10 feet equals roughly 3.048 meters. Drill rods are commonly available in both imperial (ft) and metric (m) lengths, with 3m and 10ft being very standard sizes for extension rods.
6. Material & Construction:
Made from high-strength, heat-treated alloy steel (e.g., steels meeting standards like DIN 41CrMo4 or similar).
Designed to withstand immense compressive stress from the hammer blows, significant tensile stress when pulling the string, torque from rotation, and bending forces.
Threads are precision-machined and often hardened for wear resistance.
Where it Fits in the Drill String:
1. The drill string starts with the Shank Adapter (or Drive Rod) which connects directly to the hammer in the drill rig.
2. The Starter Rod (or Coupling Rod) connects to the shank adapter. It’s often shorter.
3. Extension Rods (like this 10ft T38 rod) are then added one by one as the hole gets deeper.
4. The Drill Bit (with T38/R38 female threads) connects to the bottom of the last rod.
Key Applications:
Blast hole drilling in mining and quarries.
Exploration drilling.
Construction drilling (rock anchors, foundation holes).
Water well drilling in hard rock.
Any application requiring deep holes in rock using a top hammer rig.
Important Considerations:
Compatibility: Absolutely essential that all components (hammer shank, rods, bits) use the same thread type (T38/R38).
Thread Condition: Inspect threads regularly for wear, deformation, or cracks. Damaged threads cause energy loss, poor rotation, and rod failures.
Thread Lubrication: Always apply the correct thread grease before connecting rods. This reduces friction, prevents galling (threads welding together), improves energy transfer, and extends thread life.
Tightening: Rods must be tightened to the correct torque using proper rod wrenches to ensure a solid connection and prevent loosening.
Handling: Use proper handling equipment to avoid damaging threads or bending rods.
A 10 Ft T38 Round Threaded Extension Drill Rod is a standard 10-foot (3m) long, cylindrical steel rod with precision T38/R38 tapered threads on both ends. It’s used to extend the length of the drill string in top hammer drilling rigs, connecting between other rods to transmit impact energy and rotation from the hammer at the surface down to the drill bit at the bottom of the hole. Compatibility, proper lubrication, and careful handling are critical.
