Button Bit Regrinding Guide: When to Sharpen Carbide Buttons and When to Replace

Short answer: regrind a carbide-button rock bit before the button profile is badly flattened, not after drilling performance has already collapsed. For top-hammer and DTH button bits, the best trigger is visible wear condition rather than a fixed number of drilling meters. Sandvik’s current resharpening guidance recommends regrinding before the wear flat on any button reaches about 50% of the button diameter, and also when gauge-button anti-taper appears, surface “snakeskin” cracking begins, or penetration drops without another clear cause.

The objective is not to make an old bit look new. It is to restore the original carbide profile with minimum material removal, preserve gauge and button support, and return the bit to service before excessive wear damages penetration, hole quality, or the rest of the drill string.

1. Why Button Bit Regrinding Matters

Cemented-carbide buttons work because their profile concentrates impact and crushing energy into the rock. As the buttons wear, the working surface becomes flatter and the effective contact area increases. The bit can then require more energy to achieve the same penetration, while loads on the bit body and drilling system rise.

Sandvik states that flattened button profiles reduce drilling speed and increase risk to the bit, drill string, and rig. Its resharpening guidance also notes that systematic regrinding can materially reduce cost per drilled meter compared with running bits to destruction. The exact savings are site-specific, so treat the OEM figure as a maintenance benchmark rather than a universal economic promise.

Epiroc likewise treats regular grinding as part of rock-tool maintenance and supplies grinding systems for threaded, tapered, DTH, and COPROD button bits. The common principle is simple: maintain the carbide geometry before wear becomes severe.

2. When Should You Regrind a Button Bit?

Do not use one universal “every X meters” rule. The correct interval changes with rock abrasiveness, silica content, button shape, bit diameter, drilling pressure, rotation, flushing, operator practice, and the drilling system. Two identical bits can need very different regrinding intervals on different benches or formations.

3. Regrind Slightly Early Rather Than Too Late

One of the most expensive maintenance mistakes is waiting until the button is severely flat because the bit is “still drilling.” Sandvik explicitly advises that it is better to resharpen slightly early than to overdrill. Once the wear flat grows too large, more carbide has to be removed to recover the correct shape, the gauge can be harder to maintain, and the risk of secondary damage increases.

A practical field policy is to inspect bits at every rod change, bit change, or planned maintenance stop and record the wear pattern. If the same bit family repeatedly reaches the regrinding trigger after a similar amount of work, that historical interval can become a site-specific planning guide—but visual condition should still decide whether the bit returns to drilling.

4. Match the Grinding Cup to the Original Button Profile

Button bits are supplied with different carbide shapes, commonly including spherical and ballistic-style profiles. The grinding tool must match the button diameter and intended geometry. Epiroc’s grinding equipment documentation specifically lists grinding wheels/cups for spherical, ballistic and related profiles and emphasizes water cooling for relevant grinding systems.

Do not deliberately convert a worn ballistic button into a spherical profile, or vice versa, just because a cup is available. Changing the carbide geometry changes how the button contacts rock and can produce an inconsistent bit where different buttons carry different loads.

5. Step-by-Step Button Bit Regrinding Workflow

1. Clean the bit before inspection. Remove drilling fines, grease, and packed material so the carbide and steel around each button are visible.
2. Identify the exact bit and button profile. Record bit diameter, thread or shank system, button size, and original carbide shape. If the profile is uncertain, compare it with the supplier drawing or a new reference bit.
3. Inspect for structural damage first. A cracked steel body, loose or missing button, badly damaged flushing hole, or severely compromised thread/shank is not a normal sharpening problem. Remove the bit from routine service until suitability is confirmed.
4. Select the correct grinding cup. Match cup diameter and profile to the carbide button. Confirm the grinder’s recommended speed, pressure, coolant, and setup from its operating instructions.
5. Secure the bit. The bit should be stable enough that the grinder can follow the button axis without side-loading the cup or carbide.
6. Use controlled grinding and cooling. Apply light, consistent contact and avoid excessive dwell in one area. Where the grinding system requires water cooling, maintain adequate coolant flow to protect the cup and limit heat.
7. Restore the original profile with minimum carbide removal. The target is a functional shape, not a polished cosmetic surface. Stop once the button geometry is restored; unnecessary grinding shortens the number of future regrinds available.
8. Inspect gauge buttons carefully. Gauge wear affects hole diameter and bit contact. Check for anti-taper and confirm the bit still meets the dimensional criteria required for the drilling system.
9. Reinspect after grinding. Look for fractures, loose buttons, damaged steel, blocked flushing passages, or any button that cannot be restored safely.
10. Log the regrind. Record bit ID or batch, drilling meters/hours if available, formation, wear condition, regrind count, and any unusual damage.

6. How Many Times Can a Button Bit Be Reground?

There is no guaranteed universal number because each regrind removes carbide and the amount removed depends on how late the bit was serviced. Sandvik states that a button bit can typically be resharpened about 5–10 times depending on rock and wear conditions. Treat that as OEM guidance, not a warranty for every bit.

The practical limit is reached when the buttons, gauge, bit body, or connection can no longer be restored to a safe and useful condition. A bit that is ground early and lightly may support more service cycles than one that repeatedly arrives at the workshop heavily overdrilled.

7. When Should You Replace the Bit Instead of Regrinding?

Regrinding is for recoverable carbide-profile wear. Replacement or technical inspection is the safer decision when the problem is structural or compatibility-related.

• One or more carbide buttons are missing or visibly loose.
• The steel bit body is cracked, seriously deformed, or badly washed around the button seats.
• The gauge can no longer be maintained within the requirement for the drilling application.
• The thread, spline, or shank connection is badly damaged.
• Flushing passages are damaged in a way that cannot be corrected.
• Carbide repeatedly fractures after the operating parameters, rock condition, and grinding process have been checked.
• The remaining button height or support is insufficient for another safe service cycle according to the bit supplier or OEM limits.

Sandvik also notes that if a button has fractured, the damaged carbide should be dealt with so loose carbide fragments do not continue damaging adjacent buttons. Whether that specific bit should return to production depends on the extent of damage and the applicable tool guidance.

8. Common Regrinding Mistakes That Shorten Bit Life

1. Waiting until buttons are severely flat. This forces heavier grinding and increases the chance that gauge or button support is already compromised.
2. Using the wrong cup profile. A mismatched cup can distort the original carbide geometry.
3. Overheating the carbide or grinding cup. Follow the grinder manufacturer’s cooling procedure; Epiroc specifically emphasizes water cooling on relevant systems.
4. Removing too much carbide. Regrinding should restore profile, not maximize material removal.
5. Ignoring the steel body and connection. A perfectly shaped carbide button cannot compensate for a cracked body, damaged thread, or loose button seat.
6. Grinding only the visibly worst button. Uneven profiles around the face can create uneven loading. Inspect the complete bit.
7. Using a fixed meter interval without inspection. Rock and operating conditions change. Condition-based triggers are more reliable.

9. Top Hammer vs DTH Button Bits: Is the Grinding Principle Different?

The maintenance principle is similar: restore the original carbide profile before excessive wear develops. The actual hardware, button dimensions, face design, bit size, and grinding equipment can differ substantially. Sandvik offers resharpening equipment for both top-hammer and DTH button bits, while Epiroc’s grinding range also covers threaded and DTH tools.

For this reason, do not assume one cup or grinder setup works across every bit in the workshop. Separate grinding tools by button profile and diameter, and verify the equipment range before servicing a new bit family.

10. A Simple Field-to-Workshop Regrinding Checklist

• Bit type: top hammer or DTH
• Bit diameter
• Thread/shank system
• Button diameter and original profile
• Wear flat condition
• Gauge-button anti-taper
• Surface cracking or carbide fracture
• Steel body and button-seat condition
• Thread/shank condition
• Flushing-hole condition
• Correct grinding cup available
• Cooling method confirmed
• Regrind count logged
• Final gauge/profile inspection completed

11. What to Include in an RFQ for Replacement Button Bits

If a worn bit is no longer economical or safe to regrind, provide enough information for the replacement to match the drilling system. Include:

• drilling method: top hammer or DTH;
• rock drill or DTH hammer model;
• thread or bit-shank designation;
• required hole diameter;
• bit face design if known;
• button profile and gauge preference;
• rock formation and abrasiveness;
• photos of the worn bit face and gauge;
• current penetration/wear problem;
• quantity and destination.

Browse the current PerfoMax Drill Bits collection or the DTH Tools collection. If the bit connection or application is uncertain, send the drilling-system information and wear photos through the Request a Quote page before ordering.

FAQ

When should I regrind a button bit?

Use wear condition rather than a universal meter interval. Sandvik recommends resharpening before the wear flat on any button reaches about 50% of button diameter, and also when anti-taper develops, early surface cracking appears, or penetration falls without another clear cause.

How many times can a carbide button bit be sharpened?

Sandvik states that 5–10 regrinds can be possible depending on rock and wear conditions. The real limit depends on how much carbide is removed each time and the condition of the gauge, bit body, buttons, and connection.

Should I use the same grinding cup for spherical and ballistic buttons?

No. Match the cup to the original button diameter and profile. Using the wrong cup can change the carbide geometry and create inconsistent loading across the bit face.

Can I grind a button bit dry?

Follow the exact grinder and cup instructions. Epiroc specifies water cooling for relevant grinding systems and notes that cooling helps protect the grinding cup. Do not improvise a dry process when the equipment requires coolant.

Can a bit with a broken carbide button be reground and reused?

It requires inspection rather than automatic return to service. A fractured button can damage neighboring carbide, and missing/loose buttons or damaged steel seats are replacement or technical-review triggers. Follow the bit supplier’s limits for the actual damage.

Technical References

• Sandvik — Resharpening Equipment and Button-Bit Maintenance Guidance
• Sandvik — Resharpening Tips Poster, 2026
• Epiroc — Grinding Equipment for Rock Drilling Tools

Next Step: Regrind by Condition, Replace by Damage

The highest-value maintenance rule is to separate normal carbide wear from structural damage. Regrind early enough to restore the original button profile with minimal material removal; replace or inspect bits when the body, connection, button retention, or gauge is no longer serviceable. If you need help matching a replacement bit, send PerfoMax the drilling method, connection, hole diameter, rock condition, and clear wear photos through the RFQ page.