Problems with Using Core Drills

Troubleshooting Advice For Diamond Core Drills

This troubleshooting guide describes the most common diamond core drilling problems experienced by users and solutions on how to resolve them.

If you need further specialist advice that was not covered by this article please contact us here.


Common Problems with Diamond Core Drills in Stoneworking

Are you experiencing any of these problems while drilling?

  • Damaged or broken materials
  • Chipped or unclean holes
  • Slow drilling process
  • Damaged or broken tool

Here is a list of the first things to check

  1. Check the drill for visible damage
  2. Use a Sharpening Block to dress the drill to expose a fresh layer of diamond to cut the material. Make 3-5 drill holes in an abrasive stone such as sandstone using plenty of water. Doing this several times should be enough to wear away the metal carrier to expose a fresh layer of diamond to cut the material
  3. Check for drill run-out. This is when the tool does not rotate precisely in line with the main axis, usually resulting in a hole being bored that is larger than the diameter of the tool. A symptom of this is very high vibration while drilling. Drill a hole and measure the diameter with a caliper to see whether the hole diameter is larger than the core diameter or a misaligned hole is being drilled. If this is the case, and it is a pillar drill, clean the machine thoroughly and reassemble the drill and check for run-out again. This is often a fault of the machine, especially if you are using a hand machine like an angle grinder or an SDS drill and may require professional inspection
  4. Increase the amount of water flowing through the internal water feed in the center of the drills. Inspect the drill to ensure that there is not a core or separated debris stuck inside the shaft
  5. Check that you are using the correct Rotation Speed for Drilling Stone
  6. Reduce the drilling pressured and drill with limited pressure. Ensure that you are drilling down for approximately 30 seconds, then lift the drill up for thirty seconds. This gives the drill chance to cool down - complete this process until the hole is complete

If the problem persists, check your drilling machine. Make sure your drilling equipment is in proper condition and you have enough power to drive the core bit for the diameter of the drill and the specific material being worked.

Another option could be to use the drill on another machine and see if this resolves the problem.


Solve and Prevent Issues with Diamond Core Drills



Overheating Material While Drilling

  • There is not enough water reaching the drilling area
  • Run water through the core at a high pressure
  • Run water through the sides of the drill pointed at the drilling area

Material/Drill Vibration, Resulting in Uneven Drill Holes

  • Check your machine and rig for run out
  • Make sure the machine is mounted correctly, if using a rig
  • Make sure the core bit is tightly connected to the machine
  • Make sure the material is held securely using clamps
  • Use a Sharpening Block to dress the drill to expose a fresh layer of diamond to cut the material. Make 3-5 drill holes in an abrasive stone such as sandstone using plenty of water. Doing this several times should be enough to wear away the metal carrier to expose a fresh layer of diamond to cut the material

Excessive Chipping With Diamond Core Drills

There are many possible causes. Usually, the wrong bond has been selected for the material, the coolant rate is insufficient or the incorrect RPM speed or feed rate is being used.

  • Possible incorrect choice of diamond core drill due to a mismatch between the bond of the segment and the material. Consider a Vacuum Brazed Diamond Core Drill - these have exposed diamond on the cutting rim and are easier to use than sintered core drills
  • Check the rotation speed for the diameter of the core drill and the material- see the article: Rotation Speeds For Drilling Stone
  • Make sure the material is held securely using clamps
  • Check the condition of the machine being used
  • Make sure there is enough water in the drilling area

Diamond Drill is Drilling Material Very Slowly

This is often due to the "glazing" of the diamond segment, where the drill may have been used at an incorrect speed and the tool has become overheated, resulting in the metal bond that holds the diamond failing to wear away at the correct rate to exposure new diamond crystals.

  • Use a Sharpening Block to dress the drill to expose a fresh layer of diamond to cut the material. Make 3-5 drill holes in an abrasive stone such as sandstone using plenty of water. Doing this several times should be enough to wear away the metal carrier to expose a fresh layer of diamond to cut the material
  • Check that the core plug or debris is not lodged inside the core drill
  • Adjust the RPM speed and feed rate

Segment Loss When Core Drilling

This is the most common issue we see with core drills. It usually caused by overheating which results in a fracture at the point of the segment weld or a collision caused by an unsecured workpiece.

  • Consider using a Water Feed to run water through the internal hole of the drill
  • Check that a sufficent rate of water is reaching the driling area
  • Make sure the material is held securely using clamps
  • Check that the core plug or debris is not lodged inside the core drill

Diamond Drill Is Not Drilling or Cutting

This is also usually associated with the "glazing" of the diamond tip.

  • Check the rotation speed for the diameter of the core drill and the material, see the article: Rotation Speeds For Drilling Stone
  • Use a Sharpening Block to dress the drill to expose a fresh layer of diamond to cut the material. Make 3-5 drill holes in an abrasive stone such as sandstone using plenty of water. Doing this several times should be enough to wear away the metal carrier to expose a fresh layer of diamond to cut the material
  • Increase the RPM speed
  • Check that the core plug or debris is not lodged inside the core drill
  • Possible incorrect choice of diamond core drill due to a mismatch between the bond of the segment and the material. Consider a Vacuum Brazed Diamond Core Drill - these have exposed diamond on the cutting rim and are easier to use than other sintered core drills

Diamond Core Drill Not Lasting - Short Life Span

  • Possible incorrect choice of diamond core drill due to a mismatch between the bond of the segment and the material. Consider a Vacuum Brazed Diamond Core Drill - these have exposed diamond on the cutting rim and are easier to use than other sintered core drills
  • Check that a sufficent rate of water is reaching the driling area
  • Check that the plug or debris is not lodged inside the core drill
  • Consider using a Water Feed to run water through the internal hole of the drill
  • Check the rotation speed for the diameter of the core drill and the material- see the article: Rotation Speeds For Drilling Stone
  • Make sure the material is held securely using clamps

Adaptor Broken Away From The Diamond Core Drill Body

This fault is usually reported with larger diameter core drills with long adaptors that are much smaller than the core drill or fitting diameter itself.

  • Check the core drill to ensure that the plug or debris is not lodged inside the core drill. If this happens, water can no longer keep the diamond tips cool in the drilling zone. This can result in the overheating of the diamond segments. At this point, many operators tend to apply more pressure that results in the adaptor snapping from the shaft

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