If you’ve ever tried drilling into a concrete block or brick wall with a standard drill and steel drill bit, you’ll soon find you’re going nowhere fast. There won’t even be a dent let alone a hole to attach those fixtures you’ve been planning. Like every task, there are the appropriate tools for the job. In the case of masonry, be it different types of bricks, concrete or stone, you’ll need special drill bits and the appropriate drills to get things done. Masonry drill bits are designed differently from other drill bit types in that they need to bore through extremely hard materials. To help out, drills with considerably more power and a lot more push make drilling into masonry faster, more efficient and precise.
There are many variations when it comes to the types of masonry drill bits. What you choose will ultimately depend on the project at hand, the type of drill, the materials and the different designs and sizes of the bits.
The Job at Hand
Choosing a masonry drill bit depends on the type of materials you’ll be drilling into, and the size and depth of the hole. Standard bits are good for smaller holes into light concrete or artificial stone. But for thicker concrete blocks, bricks, marble or granite you’ll need a masonry bit with tungsten carbide or durum tip to penetrate into the hard materials at the depth you’ll be using the masonry anchor bolts or studs. Having the right bit means it won’t overheat or rupture during drilling. And the job is completed much faster as a result.
Masonry drill bits differ in the materials, and accordingly in price. Standard steel masonry bits are rarely used and won’t last long in anything more demanding. The basic starting point in durability here is HSS or High-Speed Steel and different kinds of alloys and coatings. Cobalt and black oxide coated steel bits are good in light tasks and for the occasional user. Step up to carbide, diamond powder and titanium carbon nitride coatings which provide more than enough strength, while also reducing the effects of corrosion and wear. The toughest masonry drill bits are made of tungsten carbide, and these are the ones you want when drilling into harder masonry at greater depths. Also, they’ll last the longest as they’re not affected as much by heat as other drill bits.
Masonry Drill Bit Designs and Sizes
Masonry drill bits come in different designs. There are differences in the tips, the flutes and the shank. Tips are either welded or inserted onto the drill flutes and splines. Welded tips are better at removing more materials, since the flutes are closer to the tip. Inserted tips usually retain their sharpness longer, but are preferred for softer materials. Tips can also come in 2, 3 or 4 cutting edges. Crossed tips with four cutting edges generally provide faster performance, but produce more dust.
In terms of flutes, or the slots that corkscrew along the length of the bit, masonry drill bits can be either single or double fluted. The role of the flutes is to both pierce into the material while also removing it. Double fluted bits will work faster and remove more of the masonry, meaning less cleaning afterwards.
To get the cleanest holes for inserting chemical anchors into the masonry, specially designed bits with bored holes near the tip allow for clean and quick dust removal. These so-called dustless bits also help in reducing the amount of crystalline silica dust, which can cause silicosis, a serious and potentially fatal respiratory disease.
Masonry drill bits also vary in size, depending on the diameter and depth of the hole that needs to be drilled. Diameters range from 3mm to 40mm. There are also hole saw attachments up to 10cm in diameter for creating large circular holes in bricks, stone and concrete. Overall lengths range from 60mm all the up to huge 1340mm bits for drilling into the thickest masonry.
Shanks differ in how they’re designed to fit the different drills. There are SDS masonry drill bits that have recessed shanks with sliding slots to fit into SDS rotary hammer drills. The distinction here is between SDS plus bits with 10mm shanks and SDS Max bits with a larger 18mm shank. SDS Max bits are for deeper and wider holes and are usually fitted to bigger and more powerful drills. For smaller masonry anchors, and where drilling can cause cracking, like along edges, smaller and thinner SDS plus masonry bits are preferred.
The different designs mean that certain masonry bits can be used only with a specific type of drill. Masonry bits with straight or hex shanks will only work with standard drill chucks, while SDS Plus and Max bits and only fit rotary hammer drills.
Masonry drill bits are either sold separately, especially large SDS Max bits, or either packaged in several bits in different diameters and lengths. If you can spare a few dollars, go for tungsten carbide bits, since these provide for faster and cleaner drilling and will last that much longer. Also, take into account the kind of drill you have so you don’t buy the wrong type. Consider the application where you’ll be using the masonry drill bits and go for the highest quality that your budget allows.