Quick Answer

Diamond core drilling cuts perfectly round holes in concrete, reinforced concrete, brick, and stone using a hollow drill tube tipped with diamond segments. You need three things: a core drill rig (handheld, stand-mounted, or rig-mounted), a diamond core bit matched to the material, and a water supply for wet drilling. Holes from 12 mm to 600 mm diameter are routine.

Equipment You Need

• Core drill motor: handheld for small holes; rig-mounted for holes over 100 mm or deep cores.
• Diamond core bit: laser-welded segments for reinforced concrete; silver-brazed for brick and block. Our wet diamond core bits covers wet drilling from 25 mm to 250 mm.
• Vacuum or bolt-down rig: holds the drill steady. Critical for vertical wall drilling.
• Water feed: cools the bit and flushes swarf. Required for any drill over 10 seconds.

Browse the full range in our diamond core drill bits category.

Step by Step

1. Survey. Use rebar detector. Avoid post-tension cables and conduit.
2. Mark the centre. Use a centre punch or starter bit to prevent walking.
3. Anchor the rig. Bolt or vacuum-mount the stand before starting. Handheld drilling over 100 mm is dangerous.
4. Start slow. Engage at low speed until the bit bites a guide groove.
5. Feed steadily. Let the diamonds cut—do not force. If the bit binds, withdraw and clear swarf.
6. Keep water flowing. The bit should run cool, not steaming.

Speed and Feed by Hole Size

Hole diameter	Recommended speed
12-25 mm	1500-3000 RPM
25-75 mm	600-1500 RPM
75-150 mm	300-600 RPM
150-300 mm	150-300 RPM
300 mm+	Under 150 RPM

Common Problems

• Bit walks on start: use a starter groove or centre bit.
• Segments glaze: speed too high, or no water. Slow down and check water.
• Bit binds in rebar: withdraw, rotate by hand, and use a rebar-cutting core bit.
• Core jams inside: small wedges or a core puller removes it.

Frequently Asked Questions

Q: How deep can a core drill go?

A: Standard core barrels drill 300-500 mm deep. Extension barrels go deeper, up to several metres for specialized rigs.

Q: Can I drill reinforced concrete with a standard bit?

A: Yes, but use a laser-welded bit rated for rebar. Silver-brazed bits lose segments on steel.

Q: Do I need water?

A: Almost always. Dry core bits exist for shallow, dusty work, but wet drilling doubles bit life.

Conclusion

Core drilling is precise and safe when the rig is anchored, the bit matches the material, and water is kept flowing. contact JOY TECH for core bits sized to your drill and the concrete you cut.