Extension Drill Rods by Thread Size
Our extension drill rods are designed for top hammer rock drilling and are available in a range of R-series and T-series thread sizes. With male threads at both ends, they connect through coupling sleeves to extend the drill string.
Explore the product range below to find the right thread size for your drilling equipment.
R22 Extension Drill Rods
R22 Thread
R22 threaded extension rods for compatible top hammer drilling systems. Available in different lengths to meet various drilling requirements.
R25 Extension Drill Rods
R25 Thread
R25 threaded extension rods for compatible top hammer drilling systems, available in various rod lengths and configurations.
R28 Extension Drill Rods
R28 Thread
R28 extension drill rods designed for top hammer rock drilling, with male threaded ends for connection through compatible coupling sleeves.
R32 Extension Drill Rods
R32 Thread
R32 extension rods for top hammer rock drilling, with round or hexagonal rod profiles depending on the required specification.
R38 Extension Drill Rods
R38 Thread
R38 threaded extension rods designed to work with compatible coupling sleeves and other R38 drill string components.
T38 Extension Drill Rods
T38 Thread
T38 extension drill rods for compatible top hammer drilling systems used in mining, quarrying, and production drilling.
T45 Extension Drill Rods
T45 Thread
T45 threaded extension rods for top hammer drilling applications, with rod dimensions and lengths selected to match the drilling system.
T51 Extension Drill Rods
T51 Thread
T51 extension rods for compatible top hammer drilling equipment, connecting with matching coupling sleeves to extend the drill string.
Extension Drill Rod Specifications
| Model / Connection | Rod Body / Shank | Listed Lengths (mm) | Flushing Hole (mm) | Approx. Weight Range (kg) |
|---|---|---|---|---|
| R25–Hex25–R25 | Hex 25 mm | 915, 1000, 1220, 1525, 1830, 2435, 3050 | 8.6 | 3.4–12 |
| R28–Hex28–R28 | Hex 28 mm | 3050 | 8.8 | 15 |
| R32×12–Round32–R32×12 | Round 32 mm | 600, 800, 900, 1000, 1100, 1200 | 9.2 | 3.53–7.1 |
| R32–Round32–R32 | Round 32 mm | 915, 1000, 1220, 1830, 2435, 3050, 3660 | 9.2 | 5.4–21.5 |
| HL38–Round39–HL38 | Round 39 mm | 1220, 1525, 1830, 2435, 3050, 3660, 3965, 4270, 4880, 5530, 6095 | 14.5 | 10.2–50.9 |
| HL38–Hex32–HL38 | Hex 32 mm | 1220, 1830, 2435, 3050, 3660 | 9.6 | 8.6–24.9 |
| T38–Round39–T38 | Round 39 mm | 1220, 1525, 1830, 2435, 3050, 3660, 3965, 4270, 4880, 5530, 6095 | 14.5 | 10.2–50.9 |
| T38–Hex32–T38 | Hex 32 mm | 1220, 1830, 2435, 3050, 3660 | 9.6 | 8.6–24.9 |
| T45–Round46–T45 | Round 46 mm | 1830, 2435, 3050, 3660, 4270, 5530, 6095 | 17 | 21.6–69.3 |
Need a Different Extension Drill Rod Specification?
The table above shows some of our common extension drill rod specifications. Other thread sizes, rod profiles, and lengths may be available. If you cannot find the specifications you need, please contact us. We can also discuss customized solutions based on your requirements.
What Are Extension Drill Rods?
What Are Extension Drill Rods?
Extension drill rods are threaded steel rods used in top hammer rock drilling to extend the drill string and reach greater drilling depths. Standard extension rods typically feature male threads at both ends and are connected using compatible coupling sleeves.
Available in round and hexagonal profiles, these rods are used in drilling systems for mining, quarrying, tunneling, and other rock excavation applications.
How Do Extension Drill Rods Work?
During drilling, extension rods transmit percussion energy and rotational torque from the rock drill to the drill bit. A central flushing hole allows air or water to pass through the drill string, helping remove rock cuttings from the borehole.
Multiple extension rods can be joined with coupling sleeves to achieve the required drill string length.
Extension Rods vs. MF Rods
Extension Rods
Male–Male Connection
Male threads at both ends. Separate coupling sleeves connect the rods.
MF Rods
Male–Female Connection
One male end and one female end. Compatible rods connect directly.
Key Features of Our Extension Drill Rods
Extension drill rods feature threaded ends designed to connect with compatible coupling sleeves. Different thread sizes are available to match the requirements of various top hammer drilling systems.
1. Threaded Connections
Extension drill rods feature threaded ends designed to connect with compatible coupling sleeves. Different thread sizes are available to match the requirements of various top hammer drilling systems.
2. Round & Hexagonal Rod Profiles
Available in round and hexagonal profiles, our extension drill rods offer different rod body configurations. The appropriate profile and dimensions depend on the drilling equipment and application requirements.
3. Internal Flushing Channels
A central flushing hole allows air or water to flow through the drill string, helping remove rock cuttings from the borehole. Flushing hole diameters vary according to the rod specification.
4. Multiple Length Options
Extension drill rods are available in various lengths to accommodate different drilling depths and drill string configurations. Length availability depends on the selected thread size and rod profile.
5. Steel & Heat Treatment
Steel selection and heat treatment play an important role in the strength, toughness, and fatigue resistance of extension drill rods. Proper material selection and processing help improve durability under demanding rock drilling conditions.
How to Choose the Right Extension Drill Rod
01 — EQUIPMENT
Check Your Equipment
Identify your rock drill or drilling rig model and check the existing drill string configuration. Make sure the extension rod is compatible with your drilling equipment and related components.
02 — CONNECTION
Confirm the Thread Size
Select the correct thread specification, such as R25, R28, R32, T38, or T45. Verify that the threads match your coupling sleeves and other drill string components.
03 — ROD PROFILE
Confirm the Thread Size
Select the correct thread specification, such as R25, R28, R32, T38, or T45. Verify that the threads match your coupling sleeves and other drill string components.
04 — ROD LENGTH
Determine the Required Length
Select the rod length according to the drilling depth, equipment setup, and drill string configuration. Multiple extension rods can be connected using compatible coupling sleeves.
05 — FLUSHING
Check the Flushing Hole Size
Confirm the internal flushing hole diameter and compatibility with your drilling system. Proper flushing helps remove rock cuttings from the borehole during drilling operations.
Need Help Choosing an Extension Drill Rod?
If you are unsure which extension drill rod to choose, send us your drilling equipment model, thread size, rod dimensions, required length, and quantity. Our team can help you check the suitable specifications.