As we have briefly touched on, a core drill is a drill bit which cuts large holes through masonry and concrete removing the centre part of the hole (core) as it drills and cuts its way through. As always at DIY Doctor we advise the use of purpose built tools for DIY use. Safety must always come first. Wear the appropriate safety equipment, gloves, dust masks and eye protection at all times. Keep drilling until the core drill teeth hit the surface of the wall. You will feel them bite once they do. Most domestic use diamond core cutters will always have a removable guiding drill bit which acts as a pilot hole to guide the core drill.

Before you start any drilling, the first job is to measure and mark the exact spot that you want to drill your hole so there isn’t any mistakes. With everything assembled it’s time to start drilling your hole. Position the tip of the guide drill on your drilling mark and start the drill slowly, increasing speed slightly until the pilot drill starts biting into the wall. Drilling a 6mm hole in the wrong place can easily be rectified, but trying to fill in a 4 inch hole is not an easy job at all.With the drill held straight and true, keep drilling, stopping regularly and withdrawing the bit from the hole to allow it to cool down. When withdrawing a core bit from a hole ensure that it is still rotating. There are a few different types of core bit and the best one to use will very much depend on the size and depth of hole you’re drilling and the type of material you are drilling through. There are in fact two different types of diamond core bit – wet cut and dry cut. Essentially, wet cut diamond core bits use water to cool them while drilling and dry diamond core bits are just used dry.

With the above in mind, dry cutting diamond core bits are generally used when working indoors, whereas wet cutting bits are used externally. As well as wearing the drill bit out much faster, the hammer action also creates a lot of vibration whilst drilling often leading to the hole ending up larger than intended.Unlike carbide drill bits, the teeth on a diamond core bit features diamonds that are embedded in the teeth themselves. As diamonds are extremely hard they grind their way through the surface you’re working on creating a sharp and clean cut. When hiring or buying a core bit always make sure you have the correct size and type of arbor for not only the core bit your are using but also for the type of drill you have e.g. SDS, spline, straight shank etc. However, leaving it in will allow you to see when it is about to break through the opposing side of the wall you’re drilling through. More about this and why this is a good thing can be found below. If you keep forcing the core cutter through, when you actually break through you will force a large amount masonry away from the outside of the hole, making a total mess of it all. Although it is not recommended, many use hammer action with these drill bits to increase their cutting speed and ability. This will ultimately wear the core bit out much faster, but as they are generally cheap this is not often seen as a major concern.