RockHound-Logo
GET A QUOTE

Premium Rock Drill Bits

Engineered to withstand extreme impact and abrasive conditions in mining and tunneling.

T51 Thread Retrac Button Bit
T51-95mm Retrac Button Bit-1
T51-95mm Retrac Button Bit-2
T51-95mm Retrac Button Bit-3
T51-95mm Retrac Button Bit-4
T51-95mm Retrac Button Bit-5
T51 Thread Retrac Button Bit
T51-95mm Retrac Button Bit-1
T51-95mm Retrac Button Bit-2
T51-95mm Retrac Button Bit-3
T51-95mm Retrac Button Bit-4
T51-95mm Retrac Button Bit-5

T51 Retrac Button Bits For Top Hammer Drilling

  • Category: Bits, T51
Diameter: 89, 102, 115, 127 (mm)
Buttons Gauge: 9×11, 9×12, 9×13, 9×14, 8×12 (mm)
Buttons Centere: 6×10, 6×12, 6×13, 6×11, 7×11, 7×12 (mm)
Gauge Buttons Angle: 35,35,35,35,35,35,35,35,40,40 °
Thread: T51
Weight: 4.0, 4.8, 5.8, 8.0, 4.9, 7.1, 4.7, 5.3 (kg)
Product Code : 173-8915-7805,173-0215-7805,173-1515-7805,173-2715-7805,175-8914-7805,174-8915-7805,174-0215-7805,176-8914-7805,176-8915-7864,176-0215-7864
INQUIRY NOW

How Can We Help?

home contact
VIEW DOCS
VIEW DOCS

Description

The T51 Retrac Button Bit is a top hammer drill bit designed for medium to hard rock where hole collapse or caving is a real problem. The defining feature is the retrac skirt — a reverse-taper body profile that cuts away fallen material as you pull the string back. Ordinary bits get stuck in loose or jointed ground. This one does not.

Every bit in this series is machined from 45CrNiMoV alloy steel, heat-treated for 20+ hours at controlled temperature cycles to reach the fatigue strength that modern hydraulic rock drills demand. The tungsten carbide inserts are YK05 grade — a cobalt-balanced formulation that handles high-frequency impact without cracking.

Available from 89 mm (3½″) to 127 mm (5″) in standard button, flat-face retrac, drop-center, and drop-center retrac configurations. All bits use the T51 thread standard, so they mate directly with any T51 drill rod or extension steel in your fleet.

Whether you are running bench blasts in an open-pit quarry, driving long-hole stopes underground, or drilling anchors for civil foundations, this bit is built to reduce cost-per-meter — not just drill a hole.

Material

Steel Body-45CrNiMoV
High-strength alloy steel with a 20-hour heat treatment cycle for maximum fatigue resistance.
  • Tensile strength > 1,300 MPa
  • High fatigue cycle life
  • Resists deformation under impact
  • Compatible with hydraulic drill systems
Carbide Insert-YK05
Cobalt-balanced tungsten carbide. Hard enough for granite, tough enough for jointed rock.
  • Hardness: 89–91 HRA
  • TRS > 3,000 N/mm²
  • Anti-spalling under shock loads
  • Consistent insert retention
T51 Thread Retrac Button Bit Structure Diagram

Features

  • Retrac Skirt — No Stuck Tools
    The inverted-taper body profile acts as a back-cutter on every withdrawal. Caved material around the bit gets displaced rather than packed, keeping the drill string free even in severely fractured ground. This single feature eliminates the most expensive failure mode in broken rock drilling: losing a drill string in the hole.
  • YK05 Tungsten Carbide Buttons
    YK05 grade carbide uses a controlled cobalt matrix to balance hardness and toughness. The result: buttons resist spalling on the first impact and stay sharp longer than standard-grade inserts. Available in spherical, ballistic, and parabolic profiles to match your rock’s compressive strength.
  • 45CrNiMoV Alloy Steel Body
    The body is forged from 45CrNiMoV steel and put through a 20+ hour heat treatment process. This builds the fatigue resistance needed to survive thousands of high-energy impacts per minute from a modern hydraulic rock drill — without cracking or deforming at the thread shank.
  • Drop Center Face — Straight Holes
    The concave drop-center face geometry creates a self-centering effect at the start of each hole. In jointed or hard-banded rock where deviation is common, the drop center acts as a pilot guide, keeping the bit on the planned drill vector and reducing the correction required on each pass.
  • High-Flow Flushing Channels
    Optimized hole geometry across the bit face moves cuttings out of the bottom of the hole fast. Proper flushing prevents regrinding — the biggest cause of premature button wear — and keeps bit temperature within the operating range of the carbide. Works with both air and water flushing media.
  • Precision T51 Thread
  • The T51 thread is machined to tight tolerances and hardened to prevent galling. A snug thread-to-rod interface means full energy transfer from each piston stroke to the face of the bit — not wasted in play at the connection. Decoupling after deep holes remains quick and clean.

Specifiation

All bits use T51 thread. Gauge button angle 35° standard, 40° available on select Drop Center Retrac models. Weights listed for standard carbide configuration.

Thread bit, Button D (Diameter) Buttons (No × Size mm) Gauge Button Angle Thread Product Code Weight (kg)
mm inch Gauge Centre
Button
(Standard)		 89 3 1/2 9 × 11 6 × 10 35° T51 173-8915-7805 4.0
Button 102 4 9 × 12 6 × 12 35° T51 173-0215-7805 4.8
Button 115 4 1/2 9 × 13 6 × 12 35° T51 173-1515-7805 5.8
Button 127 5 9 × 14 6 × 13 35° T51 173-2715-7805 8.0
Button / Drop Center 89 3 1/2 8 × 12 6 × 11 35° T51 175-8914-7805 4.8
Button / Flat / Retrac 89 3 1/2 9 × 11 6 × 10 35° T51 174-8915-7805 4.9
Button / Flat / Retrac 102 4 9 × 12 6 × 12 35° T51 174-0215-7805 7.1
Button / Drop Center / Retrac 89 3 1/2 8 × 12 6 × 11 35° T51 176-8914-7805 4.7
Button / Drop Center / Retrac 89 3 1/2 8 × 12 7 × 11 40° T51 176-8915-7864 4.7
Button / Drop Center / Retrac 102 4 8 × 12 7 × 12 40° T51 176-0215-7864 5.3

Custom diameters, thread sizes, and button configurations available on request. Contact the RockHound sales team for project-specific drawings.

Button Shape Comparison-Spherical vs. Ballistic vs. Parabolic

Button shape is the fastest way to tune penetration rate or service life without changing the bit body. Match the shape to your UCS range and project priority.

Button Type Features Performance Application Suggestions
Spherical Button Rounded, arc-shaped top; very thick and robust design. Exceptional durability. While penetration speed is slightly slower, it is extremely resistant to fracturing. Ideal for extremely hard rock formations or high-impact drilling environments.
Ballistic Button Pointed, streamlined top design. High Rate of Penetration (ROP). Cuts deeper into rock with 10-20% higher efficiency than spherical buttons. Best for soft to medium-hard rock, ideal for projects prioritizing rapid construction progress.
Parabolic Button A balanced hybrid design between spherical and ballistic shapes. Combines the high speed of ballistic buttons with the long service life of spherical buttons. The best-selling universal model for independent sites, offering an excellent cost-performance ratio.

How a T51 Retrac Button Bit Breaks Rock

Understanding the cycle helps you set correct drill parameters and catch wear problems early.

1.Piston Impact → Thread → Bit Face
The hydraulic rock drill fires its piston at 40–80 Hz. Each strike travels through the drill rod and into the bit body via the T51 thread. A tight thread connection is critical here — thread play wastes kinetic energy before it reaches the carbide buttons. The 45CrNiMoV body absorbs repeated shock without fatigue cracking.
2.Button Contact — Compressive Failure of Rock
The bit rotates 5°–7° between each piston strike. When a carbide button contacts fresh rock, it creates a localized stress field that exceeds the rock’s compressive strength. The rock fails in tension beneath the button — producing chips rather than dust. YK05 carbide handles this 40–80 times per second without plastic deformation.
3.Cuttings Evacuation via Flushing Channels
Compressed air or water exits through the flushing holes at the bit face. This flow picks up cuttings from the bottom of the hole and carries them to surface through the annulus between the drill string and borehole wall. Efficient flushing prevents regrinding — the single biggest source of button wear. Maintain correct flush volume for the bit diameter and depth.
4.Retrac Skirt Activates on Withdrawal
When you pull the drill string back, the retrac skirt’s reverse-taper profile engages any material that has fallen around the bit. The skirt displaces and back-cuts the debris as you withdraw, keeping the annulus clear. In standard bits, this material packs and creates the friction that causes stuck tools. The retrac design breaks that mechanism entirely.
5.Drop Center Face Maintains Hole Trajectory
The concave center geometry keeps the bit tracking straight by concentrating the initial contact force at the borehole axis. In jointed rock where deviation starts within the first few diameters, the drop center acts as a passive steering correction — no extra guidance equipment needed.

Applications

The T51 Retrac Button Bit covers the core top-hammer use cases across mining and civil construction.

  • Open-Pit Bench Drilling
    Production drilling in quarries and open-pit mines runs on cost-per-meter. This bit’s high-impact resistance and consistent hole diameter across the full run length reduce the number of bits consumed per blast pattern. The retrac skirt handles the bench floor breakage zone where bit retrieval problems concentrate.
  • Long-Hole Underground Mining
    In stope drilling, hole deviation above 2–3° causes blast fragmentation problems. The drop-center face geometry and stiff T51 thread connection keep hole deviation low in long lifters and uppers. Hole depths of 20–35 m are typical. The retrac skirt prevents string-loss incidents that cause production delays in narrow-vein operations.
  • Tunneling & Drifting
    Face drilling in tunnel headings requires consistent penetration across a full round — from easer holes through the contour. Mixed ground with fractured zones is standard in hard-rock tunneling. The retrac design handles the collar zone of each hole where broken material re-enters, without slowing the drill cycle.
  • Civil Foundation & Anchoring
    Rock anchor drilling for slope stabilization, dam foundations, and retaining walls often encounters highly fractured or weathered rock. At these sites, a stuck bit means project delay and mobilization cost. The retrac skirt is the lowest-risk option for any site where ground conditions are variable or unknown.
Applications Of T51 Retrac Button Bit For Heavy-Duty Top Hammer Drilling

Maintenance

How to Extend Bit Life in the Field

Bit life is determined as much by how you operate and maintain the bit as by the rock you drill. These four practices have the highest impact on cost-per-meter.

Grind Buttons Before They Go Flat
Button wear is acceptable until the button height drops below half its original profile. Past that point, the flat contact area grows, penetration rate falls sharply, and the heat generated in each strike starts to damage the carbide. Regrind with a button bit grinder matched to your button radius. Grinding a worn bit back to profile typically recovers 40–60% of its remaining service life.
Maintain Correct Flushing Volume
Under-flushing is the most common cause of premature wear — not hard rock. Cuttings that stay at the bottom of the hole get reground into abrasive slurry that attacks the carbide and the bit face. Check your compressor output against the bit diameter’s flushing requirement. For water flushing, maintain minimum pressure and flow rate at the bit head throughout the hole.
Inspect the Thread After Each Shift
Thread galling starts as a surface scratch and progresses to a seized connection within a few more shifts if ignored. After each shift, clean the thread with a wire brush and inspect under light for scoring, deformation, or metal transfer. Apply a thread grease rated for impact loads — standard grease is too thin and gets displaced under impact. A stripped thread in a deep hole costs far more than a tube of paste.
Rotate Your Bit Inventory
Running one bit to failure and replacing it is less efficient than rotating three or four bits through the same drill. Rotation keeps each bit in its optimal wear band, avoids the performance cliff at the end of bit life, and spreads regrinding intervals across the shift schedule. Mark each bit on entry to service and track meters drilled per bit.

How to Choose the Right T51 Bit Configuration

Condition / Priority Recommended Face Button Shape Gauge Angle Reasoning
Intact Hard Rock
(Granite, Basalt)		 Flat / Standard Button
173-xx		 Spherical 35° Maximum button durability. Flat face spreads load across all buttons simultaneously.
Fractured or Caving Ground Flat Retrac or DC Retrac
174-xx / 176-xx		 Spherical or Parabolic 35° Retrac skirt prevents stuck tools. Use parabolic if ROP is also a concern.
High Deviation Risk (Long holes) Drop Center
175-xx / 176-xx		 Spherical or Parabolic 35°–40° Concave center keeps hole straight. 40° gauge gives better wall contact in weak rock.
Speed Priority (Soft–Medium rock) Drop Center
175-xx		 Ballistic or Parabolic 35° Ballistic gives 10–20% higher ROP. Drop center stabilizes at collar to prevent deviation.
Mixed Geology
(Variable UCS)		 DC Retrac
176-xx		 Parabolic 35° Parabolic handles hard/soft layers without resharpening. Retrac covers worst-case recovery.
Lowest Cost-Per-Meter Standard Button
173-xx		 Parabolic 35° Lowest unit price. Parabolic provides best balance of ROP and regrind intervals for fleet.

Not sure which configuration suits your project? Send us your rock type (or UCS test data), target hole depth, and current drill rig model. The RockHound team will recommend a starting configuration and can supply a small trial batch before a full order.

Related Products

  • T51 Shank Adapter (Compatible with Atlas Copco, Sandvik, Furukawa)

FAQ

  • A T51 Retrac Button Bit is a top hammer drill bit that connects to a drill rod via the T51 thread standard and uses a retrac skirt — a reverse-taper body — to prevent the bit from getting stuck in fractured or caving ground. The bit face carries tungsten carbide buttons that break rock under high-frequency piston impacts from a hydraulic rock drill. The T51 thread handles impact energy levels typical of heavy-duty hydraulic equipment in the 15–25 kW power class.

A standard button bit has a straight or slightly flared skirt. When rock material caves around it during drilling, that material packs against the bit body and can trap the tool in the hole. A retrac bit has a stepped or tapered skirt that extends below the widest part of the bit. When you pull the string back, the skirt back-cuts the fallen material, keeping the borehole clear. The trade-off is slightly higher unit cost and a heavier body — but in fractured ground, a stuck standard bit costs far more than the price difference.

T51 bits cover the full UCS range from soft limestone (30–60 MPa) up to massive granite and quartzite (180–250 MPa). The selection variable is button shape, not the bit body: use ballistic buttons in soft rock for maximum penetration rate, spherical buttons in very hard rock for maximum button life, and parabolic buttons in mixed or medium-hard formations where you need both. The retrac body adds value in any formation where joints, faults, or weathering create zones of broken material.

+

T51 is an industry-standard threaded connection for top hammer drill strings, defined by a 51 mm shank diameter with a specific thread pitch and profile. It is compatible with T51 drill rods, extension steels, and shanks from all major manufacturers. If your current rods are T45, T60, or R-thread, they are not directly compatible with T51 bits — confirm your thread designation from your rod's product label or supplier before ordering.

Service life in meters drilled varies significantly by rock hardness, flushing quality, drill parameters, and regrinding practice. In medium granite with correct flushing and regrinding at the right interval, a well-maintained bit can run 200–400 meters. In hard quartzite or with poor flushing, expect 80–150 meters. The four biggest factors that shorten bit life are:

  1. regrinding too late
  2. insufficient flush volume
  3. over-rotation speed for the rock type
  4. incorrect thread lubrication causing galling. For a detailed maintenance workflow, see our guide on Top Hammer Button Bit Maintenance.

Yes. RockHound supports logo stamping on the bit body for OEM and distributor customers. The maximum imprint area is 100 × 100 mm. Custom packaging and product code re-labeling are also available. Contact the sales team with your artwork file (vector format preferred) and volume requirement for a quotation.

How Can We Help?

home contact