Core Drilling Factors to Consider

Contractors have several options when purchasing core drills, accessory, and bits. There are some common factors you should consider. Equipment needed for that occasional core in a masonry wall, is significantly different from a core drill used in demolition. 

You can increase your team’s productivity with a quick analysis of the factors that dominate your core drilling operations for your upcoming project so that the right equipment is on hand. This review includes the type of material to be cored, the depth of the coring, orientation of the coring, whether to drill wet or dry, the type of bit, and the proper operating controls.
 

Factors to Consider when Purchasing a Core Drill

Contractors use core drills for a wide number of projects. Most mechanical, electrical and plumbing contractors use hand-held core drills to drill horizontal holes through walls for passageways. Hand-held core drills are more efficient and worth the investment, as compared to trying to use a drill with a special coring bit. For these situations, pay close attention to your most common hole diameter.

Some concrete contractors use core drills for taking test samples and placing anchor embedments. If these are your common tasks, you probably need a core unit assembly that allows you to drill both horizontally and vertically (downward and upward). These units would include a stand, rig, and power unit.

The next level up is the professional concrete coring contractor. When coring is your primary business, you need a large array of drills, bits, tools, and assemblies.  

Overall, you can narrow your core drilling options by keeping track of the most common operations you encounter over the course of a construction season. So, when you sit down to look at purchasing equipment, whether for a specific project or an annual capital purchase, you should review these questions.

What type of materials do you normally core?

Unless your projects take you from coast to coast, your teams probably face the same type of materials on each coring projects. Material properties such as brittleness, size, and grain shape will be key influencers in your equipment choice.

For many, the first decision point is whether you are coring through brick, concrete masonry units (architectural block), or some thin precast elements. These materials typically have a lower compressive strength and can be cored with hand-held coring assemblies.

Conversely, if you are working on interior installations, you might encounter special substrates such as glazed tile, marble, and other types of natural stones. The properties of these materials vary significantly from common construction materials, and have a specific composition, density, and hardness.

This application will require a different core drill assembly, featuring a diamond thin wall core to minimize deformation and loss of material, leaving a cleaner, smoother hole.

Even when most of your projects revolve around reinforced concrete installations, there are some common important factors to track. For starters, the type of coarse and fine aggregates comprising the concrete will likely be similar from job to job.

But let’s say you opt to pick up a project along the coast, where the coarse aggregate is often softer. In that case you’ll need to opt for units that can slow the core drill speed to help reduce bit erosion.

Even within one concrete element there can be changes in the material’s compressive strength. The concrete placed in footings and mass pours often receive less consolidation during placement than materials placed in formed foundations and columns. The amount of steel reinforcement you may encounter may differ as well. Concrete found in industrial floors and airport runways can also vary from formed structures. 

Finally, try to assess whether your core drilling will be in material that is consistent throughout. There could be instances where lenses of softer material are sandwiched by harder material, such as in double wythe masonry walls.

What bits should you buy?

Core bits are designed to work on specific materials in specific settings. Different bits are made to operate on certain levels of toughness and resistance, so you will want to make sure that your bit is fit for the material you’re drilling on.

The basic rule for selecting a core drill bit is that you will require soft bonds for hard materials, for free and fast drilling. Similarly, abrasive, or softer materials require hard bonds for long-lasting performance. 

Diamond-tipped bits are industry-standard equipment for concrete core drills. All bits of this type have cutting surfaces made from a heat-cured mixture of industrial diamonds and powdered metal. In some cases, the bond between the cutting surface and the bit hub is quite strong. However, manufacturers also make bits with a relatively soft bond.   

Note that many drill bit manufacturers offer two classes of drill bits that are matched to your duty cycle. For simple coring operations, they offer a standard range of bits. But if you are a contract driller, you might want to invest in bits that feature a wider spaced segment design.

These bits deliver more power to the cutting surface. And when combined with additional power they provide faster coring results and higher productivity. If you’re looking for optimal results, consider custom diamond drills that perfectly suit the type of material you’re planning to drill.

How deep do your core?

The thickness of the material you’re drilling affects your decision on the type of core assembly you will purchase. Deeper cores place more stress and pressure on equipment.

Most standard concrete core equipment is centered around a 1-foot bit. When creating holes up to a foot in depth, you can safely complete your task with a drill outfitted with nothing more than a standard diamond bit.

However, for deeper holes, you’ll need to add accessories called barrel bits to your operator’s toolkit. When attached to your drill, these bits function as extenders and allow you to penetrate further into the targeted surface.

 

At what orientation do you commonly core?

You can core a straight, smooth, and round hole at almost every orientation you can imagine. But to accomplish a quality core, you need the tools that allow your operators a safe and sturdy way to position the core drill. 

For smaller horizontal coring projects, select a core drill with handles that are secure, ergonomic, and provide a good grip when wearing gloves. The unit should have enough power to core your most common hole diameter. 

For larger core drill applications, you should opt for a sturdy core stand. The stand should be matched to support the weight of your primary core machine, but durable enough to withstand rough handling that happens on many projects. Manufacturers provide stands made with cast-iron and steel. For most medium-duty applications, you could consider aluminum, as they are typically one-third the weight of a steel stand. 

Another consideration when selecting a stand is how the motor is secured. Many stands offer the option for a quick-change motor block. This feature allows the operator to attach the motor to the rig after the drill stand is set up. 

Traditionally, rig-mounted units are anchored to the floor before operation, a time-consuming process, particularly when the job requires many holes to be cut. To simplify this process, some manufacturers offer an optional vacuum base that mounts the rig to the floor. Setting up and moving the rig this way is faster, since there's no need to drill anchor holes, which can drastically increase efficiency on your customer's job.
 
When working on a flat or slightly angled surface, you can use an attachment called a vacuum stand. This type of stand relies on the power of suction to stick firmly in place while you drill. When working on a vertical or highly angled surface, you’ll need to secure your core drill in place with devices called wall anchors.
 
Regardless of the type of attachment in use, professionals often rely on additional safety chains to minimize the risks for accidental drill slippage.
 

Do you normally drill dry, wet, or wet/dry?

Core drills perform well when drilling either dry or wet. So, contractors are normally opting for assemblies that can core with the wet/dry option. There are two considerations for this option – bit wear and environmental controls. 

To minimize bit wear on projects that involve deep cores, manufacturers recommend using a minimal amount of flushing water. When delivered to the coring action, water will cool the heat that’s generated. On many types of materials, wet core drilling allows a faster penetration rate. 

Another important consideration is controlling dust emissions. The Occupational Safety and Health Administration (OSHA) has identified core drilling as a potential job condition that requires special dust containment to avoid worker exposure to silica. 

Manufacturers offer a wide array of

The thickness of the material you’re drilling affects your decision on the type of core assembly you will purchase. Deeper cores place more stress and pressure on equipment.Most standard concrete core equipment is centered around a 1-foot bit. When creating holes up to a foot in depth, you can safely complete your task with a drill outfitted with nothing more than a standard diamond bit.However, for deeper holes, you’ll need to add accessories called barrel bits to your operator’s toolkit. When attached to your drill, these bits function as extenders and allow you to penetrate further into the targeted surface.You can core a straight, smooth, and round hole at almost every orientation you can imagine. But to accomplish a quality core, you need the tools that allow your operators a safe and sturdy way to position the core drill.For smaller horizontal coring projects, select a core drill with handles that are secure, ergonomic, and provide a good grip when wearing gloves. The unit should have enough power to core your most common hole diameter.For larger core drill applications, you should opt for a sturdy core stand. The stand should be matched to support the weight of your primary core machine, but durable enough to withstand rough handling that happens on many projects. Manufacturers provide stands made with cast-iron and steel. For most medium-duty applications, you could consider aluminum, as they are typically one-third the weight of a steel stand.Another consideration when selecting a stand is how the motor is secured. Many stands offer the option for a quick-change motor block. This feature allows the operator to attach the motor to the rig after the drill stand is set up.Traditionally, rig-mounted units are anchored to the floor before operation, a time-consuming process, particularly when the job requires many holes to be cut. To simplify this process, some manufacturers offer an optional vacuum base that mounts the rig to the floor. Setting up and moving the rig this way is faster, since there's no need to drill anchor holes, which can drastically increase efficiency on your customer's job.When working on a flat or slightly angled surface, you can use an attachment called a vacuum stand. This type of stand relies on the power of suction to stick firmly in place while you drill. When working on a vertical or highly angled surface, you’ll need to secure your core drill in place with devices called wall anchors.Regardless of the type of attachment in use, professionals often rely on additional safety chains to minimize the risks for accidental drill slippage.Core drills perform well when drilling either dry or wet. So, contractors are normally opting for assemblies that can core with the wet/dry option. There are two considerations for this option – bit wear and environmental controls.To minimize bit wear on projects that involve deep cores, manufacturers recommend using a minimal amount of flushing water. When delivered to the coring action, water will cool the heat that’s generated. On many types of materials, wet core drilling allows a faster penetration rate.Another important consideration is controlling dust emissions. The Occupational Safety and Health Administration (OSHA) has identified core drilling as a potential job condition that requires special dust containment to avoid worker exposure to silica.Manufacturers offer a wide array of shrouds, dust extractors and vacuums that can minimize the amount of operator exposure. Even when coring a single hole, you should opt for dust control equipment.

How do you plan on operating your core drills?

If you plan to use your core drill occasionally with a single operator, take a close look at the feed mechanism configuration. Some core drill stands include a gear mechanism that allows the operator to move it up and down. Other stands feature a roller carriage that require fewer adjustments and maintenance than a slide carriage.
 
When setting up a coring project that involves deep holes, or several units operating at the same time, you might want to implement automatic operator control systems. These special controllers seamlessly plug into the core drill’s power system. They monitor the hydraulic pressure on both penetration and rotation. These units provide the operator with immediate feedback on the coring action. The best feature of these controls is that can quickly detect any binding or stoppage in the coring process.
 
Another advantage of these control units is increased production. These systems can quickly sense a change in the strength and density of the host materials. The controller will automatically increase the core drill’s penetration rate. This is a handy feature when you are on a large project with several core drills operating side-by side. One operator can monitor two or more core drill rigs, significantly increasing productivity. 

 

Selecting the right core drill when facing so many options

White Cap professionals have helped contractors assemble and build thousands of core assemblies for almost every type of coring project. Our experts can help you consider the most important factors when purchasing coring equipment, accessories, and associated safety items.