1.  The core bit will not cut:

• Cause: The material is too hard for the diamond specification.
• Remedy: Match the diamond specification to the material.
• Cause: The bit is glazed (smooth diamonds).
• Remedy: Re-sharpen the tool by drilling into abrasive material (sandstone, block etc.)
• Cause: Excessive speed of rotation.
• Remedy: Adjust speed of rotation.
• Cause: The cooling is excessive and causes the tool to aquaplane.
• Remedy: Reduce the water flow.
• Cause: Excessive play within the carriage guides.
• Remedy: Adjust the carriage on the slide to reduce play.
• Cause: The weight on the tool is insufficient.
• Remedy: Increase the weight on the tool.
• Cause: The machine is badly fixed.
• Remedy: Check that the machine’s fixing is correct.
• Cause: The motor is too weak.
• Remedy: Match the motor power to the diameter.

2.  Excessive wear of diamond segments:

• Cause: Insufficient irrigation.
• Remedy: Adjust the water flow.
• Cause: Insufficient speed of rotation.
• Remedy: Adjust speed of rotation.
• Cause: Excessive speed of advance.
• Remedy: Reduce speed of advance.
• Cause: The material is more abrasive than expected.
• Remedy: Use a blade with a harder diamond specification (see drill-bit selection table).
• Cause: Too much motor power applied to the tool.
• Remedy: Match the motor power to the drill diameter.
• Cause: Too much play on the machine causing vibrations.
• Remedy: Check the state of the machine.

3.  Excessive wear of core bit's steel tube:

• Cause: The machine is badly anchored.
• Remedy: Anchor the machine firmly.
• Cause: The machine is incorrectly adjusted (excessive play in the carriage guides, motor spindle or adapter out of true, etc.).
• Remedy: Correctly adjust the machine, replace worn parts, correct the play (rollers, bearings, adapters, etc.).
• Cause: The tool is warped.
• Remedy: Withdraw any warped tool. If it is relatively new, it may be straightened by the supplier.
• Cause: The bit is not correctly fixed to the motor spindle.
• Remedy: Check that the bit is correctly aligned on the motor spindle (straight line).
• Cause: There are fragments of metal in the bottom of the hole that have not been evacuated by the coolant.
• Remedy: Remove all the metal fragments from the drilled hole. Temporarily increase the flow of water to clean out the hole and remove any debris that may still be there.

4.  Segments broken and lost in the hole:

• Cause: For a bit with brazed segments, stopping the coolant even for an instant has caused the segments to heat up and destroy the brazing.
• Remedy: Always ensure the tool is correctly irrigated.
• Cause: The bit has suffered some knocks in the hole (due to steel or loose debris, etc.) and these have broken the segments.
• Remedy: Remove the bit from the machine and recover all the bits of steel, segments and debris before introducing a new bit. If any segment debris remains in the hole, there is a risk of very rapid damage to the new bit.
• Cause: Excessive speed of rotation causes heating up of the segments.
• Remedy: Take the tool out of service, replace or repair it if possible (consult supplier). Adjust the speed of rotation.
• Cause: Start up too brutal.
• Remedy: Always start drilling gently.
• Cause: Impacts due to the equipment being dropped.
• Remedy: Avoid dropping the bit on the ground as this can crack the segments.

5.  Core Bit jammed in the hole:

• Cause: Debris is blocked between the core and the bit tube (steel, pieces of material); a steel bar has been drilled “banana shaped”; it has moved during drilling and jammed the bit (wedge effect).
• Remedy: Disconnect the bit from the machine: use a spanner to turn the bit in both directions until it is released.
• Cause: Loss of side-clearance of segments.
• Remedy: Check the side-clearance of the segments. If the play is too little replace the tool.