A Guide to Core Drilling Concrete

If you are new to core drilling, or thinking about buying your first machine, this page will save you months of trial and error. We also offer a complete free video course covering everything about core drilling, in theory and in practice: every drilling method and every depth, in concrete, rock or brick.

What is core drilling?

Core drilling means cutting a clean round hole in reinforced concrete, stone or brick using a cylindrical diamond bit that spins at speed with water cooling. The hole comes out without breakage or vibration that could affect the building, in any size from 14 mm up to 20 inch, and it is used for gas, plumbing, HVAC, electrical, drainage and ventilation pipes, for rebar anchoring (fixing starter bars), and much more...

How do you choose the right core drilling machine?

• Machine size = the largest bit it runs: an 8 inch machine runs every size from ½ inch up to 8 inch, a 10 inch machine up to 10 inch, and so on.
• Handheld or stand? Handheld machines are for light work and small diameters only. Stand machines are for reinforced concrete, large diameters and repeated work.
• Oubao or Cayken? Both are original and equipped with a Safety Clutch. Oubao is the best value for money for light or moderate workloads, while Cayken is built from higher-grade materials for heavy daily core drilling.
• Gas work and anything from 2 to 7 inch: an 8 or 10 inch machine is the best fit.
• The machine comes on its own in a sealed box without core bits, and you buy bits in the sizes you need.

See all core drilling machines with prices and specifications.

How do you choose the bit?

• The bit size is the hole diameter. Note: in core drilling, one inch = 25.4 mm, which is different from the plumbing inch.
• 14 to 46 mm for rebar anchoring and fixings, 2 to 7 inch for gas, plumbing and HVAC pipes, and 8 to 20 inch for drainage, ventilation and large openings.
• For great depths, use extension rods instead of buying a longer bit.
• When the segments wear out you don’t need a new bit: segment fitting brings your bit back to full efficiency.

See core bits in every size.

The right drilling steps

1. Mark the position of the hole and make sure there are no pipes or cables in its path.
2. Fix the machine firmly: with anchors in concrete, or with the fixing jack for floor work without drilling. Weak fixing breaks segments and shakes the hole.
3. Connect a water supply (or a water pump) – cooling is what keeps your bit alive.
4. Start slowly until the bit settles into its track, then increase the pressure gradually without forcing it.
5. If the bit suddenly jams on rebar or under overload, the safety clutch disengages the drive – back off slightly and carry on.
6. When you finish, remove the core (the cut piece) and clean the dust off the bit.

When should you use a saw or a wire saw instead of core drilling?

Core drilling is for round holes. Door and window openings and cutting beams, slabs and floors are work for a concrete cutting saw with a 1 m blade and a 41 cm cutting depth, while places a saw can’t reach, or very large blocks, are cut with a concrete wire saw.

Got a job right now? Do it yourself

A core drilling machine pays for itself within the first few jobs, and every hole after that is pure profit. With the machine you get our free core drilling course, which teaches you to drill on your own from day one, and our customer service team is with you for any question.

Send us your type of work and sizes on WhatsApp at +20 106 816 7135 and we will recommend the best machine and bits for your work and budget – or visit our showroom and try it yourself.