A core drill is a drill specifically designed to remove a cylinder of material, much like a hole saw. The material left inside the drill bit is referred to as the core. Core drills used for concrete are generally called Diamond Core Drills and are water-cooled. Core drills come with several power choices including 110 volt electric, 220 volt electric, high cycle electric, pneumatic, and hydraulic (all of which require power sources such as a generator, a compressor or a hydraulic power unit).
Diamond-tipped core drills are used in new construction as well as renovations. Penetrations are needed for pipes in precast, for plumbing, for electrical conduits and wiring, HVAC, etc. in walls and floors of buildings and many industrial and residential applications. Standard materials requiring core drill penetrations commonly include asphalt, concrete, granite, stone and masonry. Common applications for the use of core drills include installing safety rails and fencing, securing benches and tables in restaurants and locker rooms, setting pipe bollards to protect store fronts and entry ways from vehicle traffic, and retrieving core samples for analysis of material.
Core drilling is possible to do yourself with a little common knowledge. There are many different types of aggregates in concrete. Using the wrong core bit can cost you more than it’s worth. Be sure to understand what you’re cutting in order to purchase the right core bit. Always seek advice from a professional. Even though they would rather you hire them to complete the job, they are normally willing to steer you in the right direction in hopes to earn your future business. Most rental companies can supply you with a 110 volt core machine normally good for drilling up to 10 inches in diameter and about 15 inches deep. You will need some way to anchor the core rig to the surface. Some rigs have a vacuum anchor base that comes with it, but this only works on good flat smooth surfaces. If you have a rough or uneven surface, the vacuum will not work. Instead, the base will need to be anchored to the surface with a quick-set anchor or drive-in anchor. Use the leveling bolts to adjust the rig to the desired angle. Don’t forget water! Although there are some dry core bits available, it is best to use water to cool your bit. Most core rigs come with a water hose adapter that can be hooked up to any garden hose. It’s important to keep the water running through the bit with enough pressure to keep the escaping water warm to the touch. If the water is hot, you could cause excessive wear or even damage the core bit. A hot bit can also glaze over the cutting edges of the diamonds. If you notice the core bit is not cutting and the water is coming out clear (no slurry or color) when you apply pressure to the handle, you can sharpen the segments using the edge of a 12″ file. Lightly strike the top of the segments to create small marks or dents in the segment. This will allow the old diamonds to fall away and new diamonds to be exposed when you start cutting again. In hard aggregates you may have to sharpen your bit many times to keep a good cutting speed. If it all seems too much, you can always hire a professional coring company when you can.
How deep can you core a hole? There really is not much of a limit on the depth of a core. The technology exists to drill as deep as needed. Using a continuous tubing you can just add as many sections of tubing needed to complete the core as long as there is enough power to rotate the drill and coolant pressure to keep the bit cool and flushed of debris. Core drills are used frequently in mineral exploration where the coring may be several hundred to several thousand feet in depth. The core samples are recovered and examined by engineers or geologists. This gives exploration companies the information they need.
How large can you core a hole? Currently most core bit manufacturers list up to 48 inches in diameter in their catalogs. They also have in print “(for 48″ and above call for price)”. So I can only say that any size is possible with enough imagination.
Diamond Drilling & Sawing LLC has been cutting concrete in Texas since 1990. If you have a coring project, we can help you figure a budget and bring your project to completion on time and within budget.