Core drilling gives you clean, precise holes in concrete, asphalt, masonry, and stone. Whether you need penetrations for plumbing, electrical conduit, anchors, or material testing, the right tools and technique make the job faster and less frustrating. This guide covers core drill motors, diamond core bits, stands, best practices, common applications, and practical tips to keep crews productive.

Core Drill Motors — match the job to the power

The motor is the workhorse. Choose based on power source, torque, and how you plan to mount the unit.

• Electric units — common on jobsites. Available in 120V and 220V models; some manufacturers offer higher-voltage options for the biggest holes.

• Hydraulic motors — used where electric power is limited or where continuous heavy-duty torque is needed.

• Handheld vs. rig-mounted — handheld drills work for small-diameter holes (typically under 3"), but anything larger and you should be on a rig or stand for accuracy and safety.

• Variable speed — important. It lets you control RPM when starting a hole, when encountering rebar, and when "opening" a glazed bit.

Concrete Core Drill Bits — pick the right bond and size

Diamond core bits are available in different bonds and segment designs. Choosing the right bit saves time and money.

• Soft bond — better for hard aggregate or high-strength concrete.

• Hard bond — better for softer, more abrasive mixes or asphalt.

• Diameter and depth — bits run from small diameters for conduit up through very large diameters for mechanical penetrations. Always confirm the motor and stand can handle the bit you select.

• Wet vs. dry — most production coring is wet to cool the diamonds and control dust; use a wet bit and good water control unless your bit is explicitly rated for dry use.

Esch Muscle Bits deliver unmatched performance. Find out how you can core drill longer, faster -  Esch Muscle Bits: Premium Core Drill Bits for Maximum Performance

Core Bit Stands & Mounting — stability equals accuracy

A solid stand keeps the motor rigid and the hole perpendicular. Stands come in vacuum, mechanical-anchor, and bolt-down varieties.

• Mechanical anchors — reliable in concrete when you can drill pilot holes for anchors.

• Vacuum bases — good for the flat, clean surfaces they work on; remember vacuum capacity drops on rough or wet surfaces.

• Jack-screw and bracing — useful on vertical drilling where additional support is needed.

• Adjustability — if you need angled cores, pick a stand rated for angle drilling and confirm reach for the bit length you plan to use.

Anchoring & Mounting Details

How you anchor depends on the substrate. A properly anchored rig reduces vibration, improves accuracy, and reduces operator fatigue.

• Concrete — mechanical anchors or vacuum bases. For mechanical anchors, use the correct size and torque and confirm anchors are set in sound concrete.

• Asphalt — use anchor bolts or spikes made for asphalt; avoid relying on vacuum when surface is uneven or oily.

• Temporary setups — when you can’t permanently anchor, use bracing and check the rig frequently during the cut.

Watch our video on How to Properly Anchor a Core Drill Rig Stand

Core Drilling: Step-by-step Best Practices

Use a consistent workflow. The following is a practical sequence you can run your crew through on every job:

1. Mark and verify hole location. Check for rebar, post-tension cables, and conduits with a rebar/utility scanner before you ever start drilling.

2. Select the correct drill motor, stand, and bit for the hole size and material.

3. Anchor the stand securely (mechanical anchor, vacuum, or bolts) and level the base so the hole will be square.

4. Start at low RPM to score the surface, then increase speed once the bit is seated.

5. Maintain steady pressure — let the diamonds do the cutting. Don’t force the bit.

6. Use a proper water flow to cool and carry slurry; adjust RPM and water if the bit glazes or the slurry looks too thin or too thick.

These steps align with proven best practices used across the industry.

Read more Best Practices for Safe & Efficient Core Drilling

Opening a Glazed or Clogged Bit (How to "Re-open" a Bit)

Bits can glaze and lose cutting performance when clogged with fine material or if they overheat. A few practical methods bring them back:

• Reduce water flow to about half, then gradually increase as the bit re-establishes cutting action.

• Introduce abrasive media to the slurry (masonry sand or sandblasting media) to help expose fresh diamond particles.

• Drill into a sacrificial, harder abrasive like a cement block or cinder block to break the glazed surface on the segments.

Water Control & RPM — read the slurry

Proper water control protects the bit, reduces dust, and keeps cuts consistent. Experienced operators watch the slurry consistency and adjust RPM/water until the slurry looks right.

Goal: slurry should look roughly like chocolate milk — not a water-washed slurry and not a dry paste. Too much water washes away the abrasive action; too little overheats and glazing follows.

Drilling Through Rebar

Hitting rebar is common. Use technique not brute force:

• When you contact rebar, reduce RPM and apply lighter, steady pressure so the bit can cut the metal rather than shock it.

• Increase water flow to help clear metal shavings from the cut.

• After passing the rebar, bring RPM and water back to your previous settings.

Common Core Drilling Applications

• Plumbing and HVAC penetrations through slabs and walls.

• Routing electrical conduit and data/utility raceways.

• Drilling for anchors, dowels, and rebar connections.

• Concrete coring for inspection, lab testing, and quality control.

• Retrofits where new pipes or sleeves need to pass through existing structures.

Accessories & Consumables to Keep Handy

• Replacement diamond bits in the right bonds and diameters for common jobs - Esch Muscle Bits Diamond Core Bits for every application.

• Anchors or vacuum plate, for secure mounting.

• Water pump to keep steady flow - the Esch EZ Pump, our automatic water delivery system .

• Slurry management options - Esch Slurry Magic or similar systems to keep the site cleaner and comply with local disposal rules.

Extra Tips for Productive Core Drilling

• Plan hole locations and confirm there are no embedded utilities with a scanner before you cut.

• Match bit bond to the concrete and aggregate type — it pays off in faster cuts and longer life.

• Keep spares on the truck: bits, anchors, pump fittings, and a backup water source.

• Train operators on anchoring, start-up procedures, water control, and how to "open" glazed bits — a skilled operator improves uptime and reduces consumable cost.

• When possible, schedule coring early in the day to avoid dusty, chaotic jobsite conditions and to get access to power and water without conflicts.

• Document the rig setup and hole parameters (bit size, RPM, water flow, anchor method) so repeat jobs run the same and you can troubleshoot problems later.

Safety Reminders (Short & Practical)

• Secure the rig before starting. Never stand on the base without it being anchored.

• Wear eye and hearing protection and proper footwear. Wet coring can make surfaces slippery — mind your footing.

• If you're coring overhead or vertically, plan for catch and containment of cores and slurry.

• Follow lockout/tagout and electrical best practices when using powered drills on live circuits or near utilities.

Closing Thoughts

Core drilling is straightforward when you pair the right motor, the right bit, and a secure stand with solid operator technique. Control water, watch the slurry, and anchor correctly — those three details alone will save time and money across most jobs.

Need recommendations for motors, stands, or bits? Our team at Esch Construction Supply can help you choose the right setup for your fleet and walk through best practices for your typical jobs. Contact Esch Supply