How to fix slow diamond core drilling
Troubleshooting Diamond Core Drilling Problems: Slow Drilling, Binding, Bit Wear & Damage
When using diamond core drill bits for concrete, you may sometimes experience slow drilling, binding, fast bit wear, or even bit damage. These issues are common but can usually be solved quickly with the right techniques. Below are the most frequent concrete drilling problems and how to fix them.
Why is My Core Drill Drilling Slowly?
Slow drilling can occur for several reasons:
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Concrete Aggregate Differences – Some types of concrete cut quickly (up to 6 inches per minute), while others are much harder and may drill as slow as ½ inch per minute.
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Weak Power Source – If your drill motor doesn’t have enough power for the bit size, drilling speed will suffer. A 30 AMP service is recommended.
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Poor Rig Anchoring – Make sure the rig is firmly anchored before drilling.
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Polished Drill Bit – When a bit becomes polished (often after hitting steel or very hard aggregate), it stops cutting effectively.
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Quick Fix: Turn off the water and drill about ½ inch with no pressure. Let the bit spin freely for about a minute to expose new diamonds. This will restore cutting performance.
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What to Do if the Core Bit is Binding
Sometimes a piece of rebar can shift inside the hole, causing the core bit to bind.
Solution:
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Uncouple the bit from the rig.
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Use a wrench on the large hex hub and carefully rotate the bit backward until it comes free.
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Remove the bit and clean the hole and the bit’s inside diameter.
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Flush out loose slurry before resuming drilling.
Why is My Core Bit Wearing Too Fast?
If your diamond bit is wearing out quickly, check these points:
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Rig Condition – Ensure the drill rig is properly aligned and anchored.
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Abrasive Concrete – Highly abrasive concrete requires a bit with a harder bond matrix.
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Steel Content – When drilling through reinforced concrete with lots of rebar, bit life will naturally be shorter.
How to Prevent Core Bit Damage
Bit damage is most common when drilling pre-stressed concrete or when using smaller diameter bits.
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Use Larger Bits – Drill through cables or heavy steel with the largest bit possible.
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Check Bit Alignment – If the motor overloads or the bit loses clearance, make sure the rig is aligned with the mast.
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Avoid Excessive Hammering – Never hammer the barrel to remove a stuck core.
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Use Enough Water – Water helps cool and lubricate the bit. If the core sticks, turn off the motor but keep the water flowing. Reach up the barrel and gently turn the core until it slides out.
Final Tips for Successful Core Drilling
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Always match your diamond core drill bit to the material.
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Maintain proper water flow to prevent overheating.
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Anchor your rig securely before starting.
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Choose the correct bond hardness for your concrete type.
By following these simple steps, you’ll improve drilling speed, extend bit life, and prevent costly downtime.
👉 At Supreme Diamond Tools, we provide high-performance diamond core bits designed for concrete drilling, reinforced concrete, and masonry applications. Contact us today to find the right bit for your job!