15 · Power Tools

Core Drill

Also called Diamond core drill · Coring drill · Core borer

Drills large, clean holes through concrete, stone and masonry with a hollow diamond bit.

Electric (corded)

Sizes & models we rent

HandheldFor smaller holes, up to about 4 inchesRig with standBolted down for big, straight holes
View in the rental catalogue ↗Compare →

Overview

A core drill cuts a clean round hole through concrete, stone or masonry with a hollow diamond bit. It grinds a ring and lifts the core out, which is why the hole has smooth sides and the concrete around it is not cracked.

We rent a handheld unit for smaller holes, up to about 4 inches, and a rig that bolts down for big holes that have to stay straight.

Pipe and conduit penetrations, plumbing and HVAC runs through slabs and walls, anchor and bolt holes, and core samples.

Start with light pressure until the bit has cut a groove to run in, then apply steady pressure. When wet coring, keep the water running to the bit — the diamond segments are held on by a bond that fails if it overheats.

Catalogue specifications

Weight: 31 lb

  • DM4096 MOTOR Specifications
  • Voltage 110 V
  • Amperage 20 A
  • No Load RPMs RPMs
  • Spindle Thread Size 1.25 - 7in 31.75 - 177.8mm
  • Suggested Drill Bit Diameter 10 in 254 mm
  • Suggested Drill Bit Diameter w/CDM3SP 12 in 304.8 mm
  • Dimensions & Weights
  • Operating Weight 24 lb 10.9 kg

Best uses

  • Pipe and conduit penetrations
  • Holes for plumbing and HVAC through slabs and walls
  • Anchor and bolt holes
  • Core samples

Troubleshooting

Bit binds or gets stuck

Checks to try, in order

  1. Release the trigger immediately.
  2. Gently rock the bit to free it; don't use the motor to force it.

Reference draft — always follow the manufacturer’s manual.

Link to this fixDid this solve the problem?
Drilling very slowly

Checks to try, in order

  1. Glazed diamond segments — sharpen by drilling briefly into an abrasive block.
  2. Check water flow when wet coring.

Reference draft — always follow the manufacturer’s manual.

Link to this fixDid this solve the problem?
Water leaking into the motor area

Checks to try, in order

  1. Stop and unplug.

Water swivel seals need replacing in the workshop.

Reference draft — always follow the manufacturer’s manual.

Link to this fixDid this solve the problem?
Tool won't switch onShared · Electric (corded)

Likely causes

  • Tripped GFCI or breaker
  • Lock-off button
  • Damaged cord
  • Dead outlet

Checks to try, in order

  1. Check the outlet works and reset any GFCI / RCD that has tripped.
  2. Release the lock-off button or safety switch before squeezing the trigger.
  3. Inspect the cord and extension lead for cuts, crushed sections or damaged plugs.
  4. If running from a generator, make sure it's running and its breaker hasn't tripped.

A damaged cord or plug means the tool is out of service. Tag it and return it — never tape a cord.

Reference draft — always follow the manufacturer’s manual.

Link to this fixDid this solve the problem?
Keeps tripping the breakerShared · Electric (corded)

Likely causes

  • Circuit overloaded
  • Undersized extension cord
  • Blunt accessory

Checks to try, in order

  1. Plug into a circuit with nothing else heavy running on it.
  2. Use a shorter, heavier extension cord. Long, thin cords starve the motor and trip breakers.
  3. Don't force the tool — a dull bit, blade or disc makes the motor draw more current.

Reference draft — always follow the manufacturer’s manual.

Link to this fixDid this solve the problem?
Overheating, burning smell or heavy sparkingShared · Electric (corded)

Checks to try, in order

  1. Stop and unplug the tool.
  2. Check the motor vents aren't blocked with dust.
  3. Let it cool, fit a sharp accessory and let the tool's weight do the work.

Heavy sparking from the vents or a burning smell that returns points to worn brushes or a failing motor — workshop only.

Reference draft — always follow the manufacturer’s manual.

Link to this fixDid this solve the problem?

Safety

  • Scan slabs for rebar, conduit and post-tension cables before coring. Never core a post-tensioned slab without engineer approval.
  • Use a GFCI when wet coring.

For electric (corded)

  • Inspect the cord and plug before every use. Use a GFCI/RCD outdoors or near water.
  • Unplug before changing blades, bits, discs or pads.
  • Wear eye protection, and a dust mask when cutting, grinding or sanding masonry.

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