Published January 12, 2026
Choosing between down-the-hole (DTH) and top-hammer drilling comes down to hole diameter, depth and the rock you are facing. Both methods transfer percussive energy to the bit, but they do it differently.
When DTH wins
DTH hammers sit just behind the bit, so impact energy is delivered directly to the rock with minimal loss through the rod string. That makes DTH the better choice for deeper holes (beyond ~15–20 m), larger diameters and straight, accurate holes in hard rock.
When top hammer wins
Top-hammer drills place the percussion unit at the top of the drill string. They excel at shorter holes, smaller diameters and high-speed production in surface mines and tunnels where rig maneuverability matters.
Quick rule of thumb
- Holes deeper than 20 m or larger than 100 mm → DTH.
- Shallow benching, tunneling, small diameters → top hammer.
- Water wells, geothermal, piling → almost always DTH.
If you are unsure, send us your hole size, depth and formation and we will recommend the right hammer and bit combination.