Drill Rod Selection Guide: Types, Sizes, and Best Practices

Drill rods are the critical link between the rock drill and the drill bit. Selecting the right rod type and size is essential for efficient energy transfer, hole straightness, and rod longevity.

Rod Types

The main drill rod types are: integral rods (for shallow holes), extension rods (for medium depths), and MF (male-female) rods for deeper drilling. Each type has specific applications and limitations.

Thread Connections

Common thread connections include R32, R38, R51, T38, T45, and T51. The correct thread depends on the rock drill model, required hole diameter, and rock conditions. Mismatched threads cause rapid wear and energy loss.

Rod Length

Standard rod lengths range from 1.2 to 6.1 meters. Longer rods reduce the number of couplings needed but are heavier and more difficult to handle. Choose the longest practical rod length for your application.

Steel Quality

High-quality drill rods are made from alloy steel with precise heat treatment. The correct hardness profile — harder at the threads, tougher in the body — is critical for fatigue resistance.

Rod Care and Maintenance

Inspect rods regularly for cracks, bends, and thread wear. Rotate rods in the string to distribute wear evenly. Store rods horizontally to prevent bending.