Drill Rods and Extension Rods
Threaded extension rods and speed rods in hexagonal and round sections that carry percussion energy from the shank adapter to the bit. Section and thread have to match the rig and the rest of the string.
Features
- Hexagonal sections are easier for the rod handler to grip and index; round sections transmit energy with slightly less loss.
- Rod length is chosen to suit the rig's feed stroke, so a rod that is nominally correct can still be unusable on a given rig.
- Thread ends are matched to the coupling and shank; mixed threads in a string destroy both the threads and the energy transfer.
- Guide rods and heavier first rods in the string reduce initial deviation, which matters most on long holes.
- Thread wear, not rod body wear, ends most rods, and thread condition should be inspected each time the string is broken.
Specifications
| Figure | Typical range | Unit | Why it matters |
|---|---|---|---|
| Thread designation | R32 / T38 / T45 / T51 | Must match the shank, couplings and bit exactly. | |
| Rod length | 3 050 - 6 100 | mm | Has to suit the rig's feed stroke, not just the hole depth. |
| Cross-section | 32 hex / 38 round / 45 round | mm | Trades handling against energy transmission and stiffness. |