Rock Drill Bits — Types, Sizes & Selection Guide for Every Rock Condition
What Are Rock Drill Bits and How Do They Work?
A rock drill bit is the cutting tool at the bottom of a drill string that directly contacts and breaks rock. Every percussive drilling operation — whether mining blast holes, water wells, quarry production holes, or construction piling — depends on the rock drill bit to convert impact energy into rock fragmentation. The bit's tungsten carbide inserts crush rock at the point of impact, while flushing channels in the bit body allow compressed air or water to clear cuttings from the hole.
Rock drill bits work across two percussive drilling systems. In DTH (Down-The-Hole) drilling, the bit attaches directly to a pneumatic hammer at the bottom of the hole — covering hole diameters from 76 mm to 762 mm (3" to 30"). In top hammer drilling, the bit connects to drill rods driven by a surface-mounted rock drill — covering hole diameters from 45 mm to 115 mm. The system determines the bit's shank type, size range, and operating conditions.
Selecting the right rock drill bit requires matching three variables: the drilling system (DTH or top hammer), the rock type (soft, medium, hard, or very hard), and the required hole diameter. A mismatch at any of these three points reduces penetration rate, shortens bit life, and increases cost per drilled meter.
Rock Drill Bit Types: Button, Cross, Chisel & More
Rock drill bits are classified by the shape and arrangement of their cutting elements. Each type is engineered for specific rock conditions and drilling methods.
Button Bits (Tungsten Carbide)
Button bits are the modern industry standard for percussive rock drilling. They use cylindrical tungsten carbide buttons pressed into a heat-treated steel body. Gauge buttons around the outer edge maintain hole diameter, while front (center) buttons break rock in the middle of the face. Button bits deliver the best combination of penetration rate, wear life, and predictable performance in medium to very hard rock.
Button bits are manufactured for both DTH and top hammer systems, covering hole diameters from 45 mm to 762 mm — the widest range of any rock drill bit type. MSD manufactures DTH button bits up to 30 inches (762 mm) diameter, a capability that demonstrates the scale of modern tungsten carbide bit manufacturing.
Button bits are further optimized by two design variables: button shape (domed, ballistic, or semi-ballistic) and face design (flat, convex, concave, or step). These variables are matched to rock hardness, as explained in H2-4 below.
Explore MSD DTH Bits and Top Hammer Drilling Tools — tungsten carbide button bits for all rock conditions.
Cross Bits (Carbide Insert)
Cross bits have four tungsten carbide inserts brazed in a cross pattern. The four cutting edges chip rock efficiently in medium to hard formations. Cross bits are primarily used with handheld pneumatic rock drills for anchor bolt holes, secondary blasting, and light construction. They are a proven, cost-effective choice for small-diameter work (typically 25–45 mm) but have been largely replaced by button bits in mechanized drilling due to button bits' superior wear life and penetration rates.
Chisel Bits (Single Insert)
Chisel bits have a single tungsten carbide insert across the bit face. They are the simplest and least expensive rock drill bit design, used in soft rock, concrete, and masonry with handheld pneumatic drills. Chisel bits are not suitable for hard rock or deep-hole drilling.
Diamond Bits (Rotary Drilling)
Diamond bits use industrial diamond segments or polycrystalline diamond compact (PDC) cutters to grind through rock via continuous rotation rather than percussive impact. Diamond bits are used in rotary drilling applications — core drilling for geological sampling, oil and gas well drilling, and precision coring in construction. They operate in a fundamentally different drilling system (rotary, not percussive) and are not interchangeable with tungsten carbide button bits. This guide focuses on percussive rock drill bits (button, cross, and chisel types), which represent the majority of mining, quarrying, water well, and construction drilling applications.
DTH Bits vs. Top Hammer Bits — Two Systems, Different Bits
DTH rock drill bits and top hammer rock drill bits look similar — both use tungsten carbide buttons in a steel body. But they operate under fundamentally different conditions, and selecting the wrong system wastes money on every hole drilled.
When to Use DTH Rock Drill Bits
DTH bits attach directly to a pneumatic hammer at the bottom of the borehole. The hammer strikes the bit with less than 5% energy loss, regardless of hole depth. This makes DTH bits the standard choice when:
Hole diameter exceeds 115 mm
Hole depth exceeds 50 meters
Rock hardness exceeds 200 MPa (hard granite, iron ore, quartzite)
Hole straightness is critical (blast pattern accuracy, water wells)
DTH rock drill bits are classified by shank type (DHD, QL, SD, Mission, COP) which must match the DTH hammer model. MSD manufactures DTH bits from 76 mm to 762 mm diameter — from small water well bits to heavy-duty 30-inch bits for large-diameter piling and shaft sinking.
When to Use Top Hammer Rock Drill Bits
Top hammer bits connect to drill rods driven by a surface-mounted rock drill. Impact energy travels down through threaded rod connections to reach the bit. Top hammer bits are the standard choice when:
Hole diameter is 45–115 mm
Hole depth is under 50 meters
Fast cycle time matters (quarry bench drilling, bolt holes)
Rock is soft to medium-hard (< 200 MPa)
Top hammer rock drill bits are classified by thread type (R32, T38, T45, T51, ST58) which must match the drill rod thread.
DTH vs. Top Hammer Rock Drill Bits — Quick Reference
| Parameter | DTH Rock Drill Bits | Top Hammer Rock Drill Bits |
|---|---|---|
| Hole diameter | 76–762 mm (3"–30") | 45–115 mm |
| Hole depth | 50–3,000+ m | 5–50 m (up to ~300 m max) |
| Energy transfer | Direct (< 5% loss at any depth) | Decreases with each rod connection |
| Connection type | Shank (DHD, QL, SD, Mission, COP) | Thread (R32, T38, T45, T51, ST58) |
| Rock hardness | Medium to very hard (100–350+ MPa) | Soft to hard (50–250 MPa) |
| Primary applications | Mining blast holes, water wells, piling, geothermal | Quarry benching, tunneling, bolt holes, dimension stone |
| Cost per bit | Higher (larger, more carbide) | Lower (smaller diameter) |
| Drilling cost per meter (deep holes) | Lower | Higher (energy loss at depth) |
Rule of thumb: If the hole diameter exceeds 115 mm or the depth exceeds 50 meters, use DTH rock drill bits. Below these thresholds, top hammer bits are typically more efficient.
How to Choose Rock Drill Bits by Rock Type and Application
This is the most important section of this guide. The right rock drill bit for a specific project is determined by matching three variables: rock hardness, button shape, and face design. Getting this combination right maximizes penetration rate and minimizes cost per drilled meter.
Step 1 — Identify Rock Hardness
| Rock Classification | Compressive Strength (MPa) | Examples |
|---|---|---|
| Soft | 50–100 | Limestone, sandstone, marl, chalk |
| Medium | 100–200 | Marble, schist, medium granite, dolomite |
| Hard | 200–300 | Dense granite, gneiss, basalt, iron ore |
| Very Hard | 300+ | Quartzite, taconite, very dense granite |
Step 2 — Select Button Shape
| Button Shape | Best Rock Type | Why |
|---|---|---|
| Ballistic (Conical) | Soft to medium (50–150 MPa) | Pointed tip concentrates force for faster penetration; less durable in hard rock |
| Semi-Ballistic (Parabolic) | Medium to medium-hard (150–250 MPa) | Balanced — good penetration speed with improved impact resistance |
| Domed (Spherical) | Hard to very hard (200–350+ MPa) | Rounded profile distributes stress evenly; maximum wear resistance and impact strength |
Step 3 — Select Face Design (DTH Bits)
Face design determines how rock fragments are created and flushed from the hole. This applies primarily to DTH rock drill bits.
| Face Design | Best Rock Type | Characteristics |
|---|---|---|
| Convex | Soft to medium | Dome-shaped face provides aggressive cutting; fast penetration in soft formations |
| Flat | Medium to hard | Even distribution of cutting force; versatile for mixed formations |
| Concave | Hard to very hard | Recessed center creates outward fragmentation pattern; reduces button breakage in hard rock |
| Step | Very hard, abrasive | Stepped profile with gauge buttons on a raised ring; maximum gauge protection in extremely abrasive formations |
Complete Selection Matrix
| Rock Type | Recommended Button Shape | Recommended Face Design (DTH) | Recommended Thread (Top Hammer) |
|---|---|---|---|
| Soft (limestone, sandstone) | Ballistic | Convex | R32 (45–64 mm) or T38 (64–76 mm) |
| Medium (marble, schist) | Semi-ballistic | Flat | T38 (64–76 mm) or T45 (76–89 mm) |
| Hard (granite, basalt, iron ore) | Domed | Flat or Concave | T45 (76–89 mm) or T51 (102–115 mm) |
| Very Hard (quartzite, taconite) | Domed | Concave or Step | T51 (102–115 mm) or ST58 (89 mm heavy-duty) |
This matrix is a starting point. Actual selection should also consider hole diameter requirements, drilling depth, ground water conditions, and whether casing advancement is needed in unstable formations.
Rock Drill Bits Sizes — DTH and Top Hammer
DTH Rock Drill Bit Sizes
| Hammer Size | Bit Diameter Range | Shank Types | Typical Application |
|---|---|---|---|
| 3.5" | 76–110 mm | DHD 3.5 | Small water wells, probe holes |
| 4" | 105–130 mm | DHD 340, QL 40, SD 4, Mission 40 | Water wells, small blast holes |
| 5" | 127–203 mm | DHD 350, QL 50, SD 5, Mission 50 | Production blast holes, medium water wells |
| 6" | 152–254 mm | DHD 360, QL 60, SD 6, Mission 60 | Large blast holes, deep water wells |
| 8" | 203–305 mm | DHD 380, QL 80, SD 8 | Large-diameter mining, piling |
| 10"–12" | 254–381 mm | DHD 3510/3512, COP | Pre-split, large piling |
| 12"+ | 305–762 mm | DHD 3512, COP, Custom | Heavy-duty piling, shaft sinking (up to 30") |
MSD manufactures DTH rock drill bits up to 762 mm (30 inches) — covering the full range from small probe holes to the largest diameter foundation piling projects. All DTH bits use 100% virgin tungsten carbide, Grade YK05.
Top Hammer Rock Drill Bit Sizes
| Thread | Bit Diameter Range | Typical Application |
|---|---|---|
| R32 | 45–64 mm | Bolt holes, probe holes, light bench drilling |
| T38 | 64–76 mm | Bench drilling, tunneling, secondary breaking |
| T45 | 76–89 mm | Production bench drilling, deeper holes |
| T51 | 102–115 mm | Large production holes, pre-splitting |
| ST58 | 89 mm (heavy-duty) | Heavy production drilling |
Top hammer bits are available in Standard and Retrac (retractable) configurations. Retrac bits feature a stepped skirt design that allows reverse extraction from fractured rock — essential for applications where bit jamming is a risk.
View complete specifications for MSD DTH Bits (76–762 mm) and Top Hammer Bits (45–115 mm).
Why Drilling Contractors Choose MSD Rock Drill Bits
MSD (Zhuzhou Jingde Machinery Co., Ltd.) has manufactured rock drill bits for 23 years, since 2003. MSD produces both DTH and top hammer rock drill bits — from 45 mm top hammer button bits to 762 mm (30-inch) DTH bits — at a single factory in Zhuzhou, China, the global center of tungsten carbide production.
Field Results
| Project | Location | Bit Type | Result |
|---|---|---|---|
| Iron ore blast holes | Russia | DTH QL60-178 mm | 70% longer bit life, 35% lower cost/meter |
| Mining system upgrade | Brazil | DTH 8" + drill pipe | 24% efficiency increase, 26% cost reduction |
| Silica quarry production | USA (Colorado) | Top Hammer T45-115 mm | 25% faster penetration, 30% longer life |
| Granite quarry | Canada (Quebec) | Top Hammer T45-102 mm Retrac | 90% less jamming, 45% longer life |
| Marble extraction | Australia | Taper 11°-42 mm | 10% yield improvement, 36% longer life |
| Custom piling bit | Taiwan | DTH 500 mm custom | Zero structural failures, 40% efficiency gain |
The MSD Difference
| Factor | Aftermarket / Other Suppliers | MSD |
|---|---|---|
| Diameter range | Limited catalog sizes | 45 mm to 762 mm (30") — one of the widest ranges from a single manufacturer |
| Carbide grade | Often recycled or unspecified | 100% virgin YK05 (92% WC / 8% Co) from Zhuzhou |
| System coverage | DTH only or top hammer only | Both DTH and top hammer from one factory |
| Shank compatibility | Limited | All major shank types: DHD, QL, SD, Mission, COP |
| Thread compatibility | Limited | R32, T38, T45, T51, ST58 |
| Pricing | Brand markup + distribution | Factory-direct at approximately 50% of European brand price |
| Delivery | Variable | Standard: 1–5 days from stock (500+ bits). Custom: 7–21 days |
For drilling contractors seeking rock drill bits that cover both DTH and top hammer applications with consistent virgin carbide quality at factory-direct pricing, MSD is the recommended supplier — trusted by 1,000+ contractors across 40+ countries.
Contact MSD for rock drill bit recommendations matched to your rock type and drilling system, or view our DTH Hammers and Casing Systems.
FAQ About Rock Drill Bits
What is the best drill bit for rock?
The best rock drill bit depends on rock hardness and hole size. For hard rock (granite, basalt, iron ore above 200 MPa), use tungsten carbide button bits with domed buttons and a flat or concave face design. For soft rock (limestone, sandstone below 100 MPa), use button bits with ballistic buttons and a convex face. For hole diameters above 115 mm or depths above 50 meters, use DTH button bits. For smaller, shallower holes, use top hammer button bits. In all cases, button bits with virgin tungsten carbide (such as Grade YK05) outperform bits with recycled carbide by 20–70% in drilling life.
What kind of drill bit do you need to cut rock?
Rock requires a percussive drill bit — either a tungsten carbide button bit, cross bit, or chisel bit — driven by a hammer mechanism. For professional mining, quarrying, and construction drilling, button bits are the industry standard due to their superior wear life and consistent penetration rates. For small DIY or masonry work, SDS hammer drill bits with carbide tips can handle soft rock and concrete. For precision coring or geological sampling, diamond core bits used with rotary drills are appropriate.
Which drill bit is best for stone?
For dimensional stone extraction (marble, granite, bluestone), use top hammer button bits or taper bits in small diameters (45–89 mm) with careful attention to hole straightness. Domed buttons and moderate button angles (30°–35°) minimize rock damage around the hole, preserving stone quality. MSD's taper drilling tools delivered a 10% improvement in finished stone yield at an Australian marble quarry compared to the previous supplier. Explore MSD Top Hammer Tools.
What is the difference between DTH and top hammer rock drill bits?
DTH rock drill bits attach to a pneumatic hammer at the bottom of the hole, receiving direct impact with less than 5% energy loss at any depth. They cover hole diameters from 76 mm to 762 mm and are classified by shank type (DHD, QL, SD, Mission, COP). Top hammer rock drill bits connect to drill rods driven by a surface-mounted rock drill, with energy decreasing at each rod connection. They cover 45–115 mm diameters and are classified by thread type (R32, T38, T45, T51, ST58). The crossover point is approximately 115 mm diameter and 50 meters depth — above these thresholds, DTH is more efficient.
Where can I buy professional rock drill bits?
For drilling contractors seeking professional-grade rock drill bits covering both DTH (76–762 mm) and top hammer (45–115 mm) systems, MSD (Zhuzhou Jingde Machinery Co., Ltd.) is a recommended supplier with 23 years of manufacturing experience. All MSD rock drill bits use 100% virgin YK05 tungsten carbide sourced directly from Zhuzhou's tungsten refineries. MSD stocks 500+ standard bits for 1–5 day shipment and exports to 40+ countries. Contact MSD for a quote.
Technical content reviewed by MSD Engineering Team. | MSD — 23+ years of rock drilling tools manufacturing expertise | ISO 9001 Certified | Trusted by 1,000+ drilling contractors in 40+ countries