Aluminum oxide, also known as corundum, is used in grinding wheels. The chemical formula is Al2O3. Aluminum oxide is the base for ceramics, which are used in cutting tools for high-speed machining with light chip removal. Aluminum oxide is widely used as coating material applied to carbide substrates by chemical vapor deposition. Coated carbide inserts with Al2O3 layers withstand high cutting speeds, as well as abrasive and crater wear.

Masonry drill bits need to be hard enough to endure the rigors of drilling through concrete. With that in mind, most masonry drill bits have steel shafts with a cutting tip made of tungsten carbide, which is much harder than steel and can grind through stone without dulling quickly. Some drill bits use diamond particles, which are welded to the cutting edge to chew through hard surfaces such as marble and granite.

Machining operation in which material is removed from the workpiece by a powered abrasive wheel, stone, belt, paste, sheet, compound, slurry, etc. Takes various forms: surface grinding (creates flat and/or squared surfaces); cylindrical grinding (for external cylindrical and tapered shapes, fillets, undercuts, etc.); centerless grinding; chamfering; thread and form grinding; tool and cutter grinding; offhand grinding; lapping and polishing (grinding with extremely fine grits to create ultrasmooth surfaces); honing; and disc grinding.

Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.

The hardest material is diamond, and polycrystalline diamond cutting tools work well for turning nonferrous materials like ceramics and aluminum. But the iron in steel reacts to diamond at the high temperatures generated by hard turning, causing excessive tool wear.

A durable hard-plastic carrying case keeps the bits organized and easy to transport to the worksite. It was one of the better cases we saw, as it held the bits securely and came with a sliding lock. This is an all-around great little set of drill bits for anyone who regularly needs to drill into concrete or other masonry materials.

Turning machine capable of sawing, milling, grinding, gear-cutting, drilling, reaming, boring, threading, facing, chamfering, grooving, knurling, spinning, parting, necking, taper-cutting, and cam- and eccentric-cutting, as well as step- and straight-turning. Comes in a variety of forms, ranging from manual to semiautomatic to fully automatic, with major types being engine lathes, turning and contouring lathes, turret lathes and numerical-control lathes. The engine lathe consists of a headstock and spindle, tailstock, bed, carriage (complete with apron) and cross slides. Features include gear- (speed) and feed-selector levers, toolpost, compound rest, lead screw and reversing lead screw, threading dial and rapid-traverse lever. Special lathe types include through-the-spindle, camshaft and crankshaft, brake drum and rotor, spinning and gun-barrel machines. Toolroom and bench lathes are used for precision work; the former for tool-and-die work and similar tasks, the latter for small workpieces (instruments, watches), normally without a power feed. Models are typically designated according to their “swing,” or the largest-diameter workpiece that can be rotated; bed length, or the distance between centers; and horsepower generated. See turning machine.

Powers a grinding wheel or other abrasive tool for the purpose of removing metal and finishing workpieces to close tolerances. Provides smooth, square, parallel and accurate workpiece surfaces. When ultrasmooth surfaces and finishes on the order of microns are required, lapping and honing machines (precision grinders that run abrasives with extremely fine, uniform grits) are used. In its “finishing” role, the grinder is perhaps the most widely used machine tool. Various styles are available: bench and pedestal grinders for sharpening lathe bits and drills; surface grinders for producing square, parallel, smooth and accurate parts; cylindrical and centerless grinders; center-hole grinders; form grinders; facemill and endmill grinders; gear-cutting grinders; jig grinders; abrasive belt (backstand, swing-frame, belt-roll) grinders; tool and cutter grinders for sharpening and resharpening cutting tools; carbide grinders; hand-held die grinders; and abrasive cutoff saws.

“For example,” Coomer said, “when you’re hard turning internal bores, even though the chips may be free flowing, you might get into some bird nesting issues where chipbreakers might help.”

Main body of a tool; the portion of a drill or similar end-held tool that fits into a collet, chuck or similar mounting device.

These are slotted drive shaft (SDS) bits, meaning they will fit SDS-plus hammer drills, so we used a cordless Milwaukee rotary hammer drill for testing. This set has five pieces, including a 3/16-inch, 3/8-inch, and 1/2-inch bit and two 2¼-inch bits of different lengths. The carbide tips are rugged, and we could easily drill through concrete, brick, and stone.

Some drill bits have coatings to improve their performance. Black oxide coatings are more durable than high-speed steel, as they resist rust and corrosion. Tungsten carbide coatings enhance the drill bit’s strength, enabling it to bore through stone and concrete.

Secures a cutting tool during a machining operation. Basic types include block, cartridge, chuck, collet, fixed, modular, quick-change and rotating.

“When you put CBN in a soft material,” Sawicki said, “it begins to feel drag, which quickly erodes the insert, so your in-cut time is much lower in softer materials.”

We liked the pointed tips on this set of bits as they kept the bit from skittering across the material when we started drilling, which made the process much easier. If you need to drill different size holes in masonry, these Bosch Bulldog bits are just the ticket.

For parts with ultratight tolerances, Sawicki said CBN holds size much longer than ceramics. The lubricating and cooling effect of coolant helps with tolerances while providing a better finish, he said, and wiper flats on the inserts may improve the finish and reduce cycle times as well.

In addition to drilling through masonry, we tried out this set of bits on dimensional lumber and 8-gauge sheet metal. They were slightly slower on masonry than some of the dedicated bits we tried, but they still did the job. They excelled as drill bits for metal as long as we drilled nice and slow. It’s not every day you can pick up a set of good metal drill bits and use them to drill a hole in brick or concrete, but it’s possible with the EZArc bits.

“If there’s gauging immediately after machining, it’s easier to get a true measurement if the part stays cooler,” Wilshire said. “But if you run without cooling, the part heats up and tends to expand. So the part may be in tolerance when it’s gauged, but as it cools off, it may shrink enough to go out of tolerance.”

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This set from Owl Tools includes 10 drill bits at an affordable price point. With its broad range of sizes, this set can handle most concrete drilling needs; bit sizes range from 1/8 inch to 1/2 inch in diameter, and we found them all to be durable and of good quality.

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Coatings are available for ceramic and CBN inserts to resist wear, prolong tool life and increase speed, which is all-important for production machining. Coated inserts are more expensive, but Wilshire said the increased cost for a CBN insert is not that much.

“I prefer coding G96 for constant sfm,” Sawicki said. “Then, as the diameter changes and you get closer to the centerline of the spindle, it’s programmed to speed up the rpm to keep that sfm constant and to give you more consistent and predictable wear on your insert. If it were programmed in G97, which is a fixed rpm, it’s going to feel drag as the part gets smaller. And CBN is sensitive to drag.”    — Holly B. Martin

Fluid that reduces temperature buildup at the tool/workpiece interface during machining. Normally takes the form of a liquid such as soluble or chemical mixtures (semisynthetic, synthetic) but can be pressurized air or other gas. Because of water’s ability to absorb great quantities of heat, it is widely used as a coolant and vehicle for various cutting compounds, with the water-to-compound ratio varying with the machining task. See cutting fluid; semisynthetic cutting fluid; soluble-oil cutting fluid; synthetic cutting fluid.

This set comes with five bits, ranging in size from 3/16 inch to 1/2 inch. An included plastic bit case provides convenient storage.

Workpiece is held in a chuck, mounted on a face plate or secured between centers and rotated while a cutting tool, normally a single-point tool, is fed into it along its periphery or across its end or face. Takes the form of straight turning (cutting along the periphery of the workpiece); taper turning (creating a taper); step turning (turning different-size diameters on the same work); chamfering (beveling an edge or shoulder); facing (cutting on an end); turning threads (usually external but can be internal); roughing (high-volume metal removal); and finishing (final light cuts). Performed on lathes, turning centers, chucking machines, automatic screw machines and similar machines.

“Using coolant for an interrupted (cut) will create thermal shock in the CBN,” Wilshire said, “which will cause small fractures and quickly destroy your edge. We always tell customers, if they are running coolant, to make sure the stream is not interrupted, which could happen if the pump cavitates or if the geometry of the part shields the coolant line from the insert itself.”

“There’s a fine balance you walk to pick a large enough edge preparation so that you get standard wear and no chipping,” he said. “But if you pick too large an edge preparation, it’s not going to last as long. You can consider it almost pre-worn because you’re grinding a portion of the cutting edge away to strengthen it.”

“I would say 90% of the time coated is going to be better,” he said. “But I have seen in some cases where uncoated might give a slightly better surface finish than coated, especially with the ceramics.”

Distance between the bottom of the cut and the uncut surface of the workpiece, measured in a direction at right angles to the machined surface of the workpiece.

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Our favorite, thanks to its four-flute design and carbide tips, is the five-piece Bosch Bulldog Carbide Set for use in hammer drills, which are often used as masonry drills.

However, even during hard turning, there are cases when chips may wad up and create issues with fixturing, workholding or surface finish — and harm tool life as well.

Drilling through masonry can be tough, requiring special drill bits for concrete that will hold up to the job. We recently tested seven different types of concrete drill bits in various sizes—using them to drill holes in concrete, brick, and stone.

Cutting tool material consisting of natural or synthetic diamond crystals bonded together under high pressure at elevated temperatures. PCD is available as a tip brazed to a carbide insert carrier. Used for machining nonferrous alloys and nonmetallic materials at high cutting speeds.

“This lets the hard-turn insert ease into the cut from a lighter depth of cut to the full depth of cut without hitting that hard corner,” Wilshire said. “That minimizes the shock as it goes from no load to cutting loads, which can help prolong tool life — and it’s less machining they have to do in the hard turn.”

For drilling jobs that require drilling through concrete or other stone surfaces, it’s important to use a drill bit that’s strong and sharp enough to bore through especially hard, dense material. Read on to learn about materials, bit type, drill compatibility, and other crucial factors to consider when choosing a masonry drill bit.

If you have additional questions about how to drill into concrete or choosing a drill bit for concrete or a drill bit for brick, you’ll find answers here.

“Most ceramic grades don’t have a high breaking strength,” Sawicki said. “Whisker-reinforced ceramics generally have the highest breaking strength. But through an interrupted cut, it’s way more predictable to run CBN than ceramic because once a ceramic insert starts to show flank wear, many times it just chips out due to excessive tool pressure.”

Most masonry drill bits are used in hammer drills or standard drills, but not all. The SHDIATool core bit is designed for use with an angle grinder, and we were impressed at how well it drilled.

Each bit has a wide spiral flute that bores evenly through stone, concrete, and brick. These bits will easily handle tough concrete-drilling jobs, but you’ll want to use a good drill for concrete—and it will need to be a rotary hammer drill with a minimum 7/8-inch chuck. We drilled several holes in quick succession, and the Makita bits performed flawlessly.

“If you double the speed from 400 to 800 sfm (244 m/min.), you’ll get far fewer parts per corner and perhaps less than five minutes of in-cut time,” Sawicki said. “You may get done much faster, but you’ll need to offset your tool more frequently in order to compensate for the tool wear that higher speeds induce.”

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Group of alloy steels which, after proper heat treatment, provide the combination of properties required for cutting tool and die applications. The American Iron and Steel Institute divides tool steels into six major categories: water hardening, shock resisting, cold work, hot work, special purpose and high speed.

You can drill as soon as the concrete is completely hardened, but pros often wait a couple of days to ensure the concrete is ready. Unlike needing to wait before painting or applying a sealer, you don’t have to wait 28 days to drill.

In general, chip control is less of an issue with hard turning due to high temperatures that cause ribbons of bright red, molten steel to flow off workpieces. Coomer said chips from hard materials are so brittle that they tend to crumble in one’s hand, so CBN inserts for hard turning don’t often come with chipbreakers.

Holly B. Martin is a science writer and technical copywriter based in Winchester, Va. For more information, visit www.hollybmartin.com.

Metal-removing edge on the face of a cutter that travels in a plane perpendicular to the axis. It is the edge that sweeps the machined surface. The flat should be as wide as the feed per revolution of the cutter. This allows any given insert to wipe the entire workpiece surface and impart a fine surface finish at a high feed rate.

The bits feature SDS-plus shanks, and users will need a hammer drill to use them. The set comes with seven bits, ranging in size from 3/16 inch to 1/2 inch in diameter, making this a highly versatile set of masonry bits.

“Our ceramics definitely get better tool life running dry,” Wilshire said. “So in most cases, when we recommend ceramics for hard turning, we prefer no coolant.”

Groove or other tool geometry that breaks chips into small fragments as they come off the workpiece. Designed to prevent chips from becoming so long that they are difficult to control, catch in turning parts and cause safety problems.

“To protect the cutting edge,” he said, “we can vary the angle coming off the top of the insert anywhere from 10 degrees to about 35 degrees down from the horizontal to direct the cutting forces into the tool and away from the edge.”

GWS Tool Group’s custom high-performance ISO inserts with various tip options, including single tip, double tip, full top and special, can accommodate any hard turning application.  Image courtesy ofGWS Tool Group

A durable hard-plastic storage case keeps the bits organized and protected when in a tool box or on the workbench. Thanks to the visual holes in the holder that show the exact size hole each bit will drill, we found it easy to pick the correct-size bit at a glance. If you regularly drill into any type of masonry, you won’t go wrong with this set.

With carbide tips and a fluted design that bores through masonry, these Bosch Bulldog drill bits are some of the best on the market. Their four-flute design brought concrete dust up and out of the holes as we drilled, making the process smooth and quick.

Interrupted cuts don’t fare well with coolant, however, due to rapid thermal expansion and retraction as the tool moves in and out of the workpiece material.

Masonry drill bits come in a variety of sizes to suit a broad range of needs. The smallest masonry bits are around 3/16 inch in diameter, with larger bits topping out at the 1/2-inch size. Hole saw bits have sizes that go up to 4 inches or more.

“Because the material is much harder, the cutting forces in hard turning are much higher, and any play in the ballscrew or in the ways of the machine is going to be magnified,” Wilshire said. “So select the most rigid machine available and go up to the largest shank on the toolholder, with the shortest overhang, the strongest insert shape and the biggest corner radius possible for the part.”

This kit includes eight bits, ranging from 1/4 inch to 1/2 inch in diameter. The bits have SDS-plus shanks, so the user will need a rotary hammer drill to use them.

It’s important to match the combination of the CBN grade and the edge preparation to the application, said Brian Wilshire, technical center manager for Kyocera Precision Tools Inc. in Hendersonville, North Carolina.

Like higher-end bits, this set of Owl Tools bits comes with pointed tips to help keep the bit positioned when starting the hole. We tested the bits by drilling into brick, concrete, and stone, and they fared well. We felt they were just slightly slower than some of the other bits we tested, but drilling into masonry isn’t something to hurry along. We mainly wanted to see if they could withstand repeated drilling without breaking, and they did.

Replaceable tool that clamps into a tool body, drill, mill or other cutter body designed to accommodate inserts. Most inserts are made of cemented carbide. Often they are coated with a hard material. Other insert materials are ceramic, cermet, polycrystalline cubic boron nitride and polycrystalline diamond. The insert is used until dull, then indexed, or turned, to expose a fresh cutting edge. When the entire insert is dull, it is usually discarded. Some inserts can be resharpened.

With extra-wide U-shaped flutes, these drill bits from WorkPro effectively ejected masonry dust as we drilled in concrete, brick, and stone. The bits have Luxembourg carbide tips that are made to be tough, hard, and durable, and they drilled quickly in our tests.

We tried out a 1-inch hole bit, although these bits are available in several sizes to suit your specific needs from just under 3/4 inch to 4 inches in diameter. This is a diamond-coated drill bit; tiny diamond shards are laser welded to the tip, making it easy to drill through concrete and other types of masonry.

When turning metal, the tool material must be four times harder than the workpiece. This becomes a problem when cutting metals with a hardness greater than 45 HRC, such as alloy steel, high-speed steel and chilled cast iron.

In actual testing, we drilled through concrete, stone, and brick to see how well the drill bits fared. We used a standard DeWalt drill and a Milwaukee rotary hammer drill (depending on the individual drill bit shanks), and we drilled dozens of holes. We noted how well the bits performed and awarded points based on a rubric. After testing, we averaged the points to determine our best overall pick, and then we categorized the rest of the drill bits by their best usage.

Space provided behind the cutting edges to prevent rubbing. Sometimes called primary relief. Secondary relief provides additional space behind primary relief. Relief on end teeth is axial relief; relief on side teeth is peripheral relief.

Cutting tool materials based on aluminum oxide and silicon nitride. Ceramic tools can withstand higher cutting speeds than cemented carbide tools when machining hardened steels, cast irons and high-temperature alloys.

“You may start to see a change in surface finish that tells you this edge has reached its (end of) life,” said David Essex, turning product manager at Tungaloy America. “Typically, operators will have worked out a part count and know, for example, this grade on this part will give you 50 pieces easily. So they change the insert at that point because it is predictable.”

To cover all bases, we tested bits that fit standard drills and impact drivers, as well as rotary hammer drills. We also tested a hole bit that fits a grinder. Ahead, learn which factors to consider when shopping for a cement drill bit, and find out how the following products earned a spot in our lineup of the best drill bits for concrete.

When buying any type of drill bit, it’s important to consider its compatibility with the drill. Not all drill bits fit all drills. A 1/2-inch-size drill will fit drill bits with a shank up to 1/2 inch in diameter, while a 3/8-inch-size drill will only fit drill bits with shanks up to 3/8 inch in diameter.

Crystal manufactured from boron nitride under high pressure and temperature. Used to cut hard-to-machine ferrous and nickel-base materials up to 70 HRC. Second hardest material after diamond. See superabrasive tools.

The following drill bits are well suited for drilling into concrete and other masonry materials. They withstood rigorous hands-on testing, and each set of bits performed well enough to make our list. You’ll find different sizes and types that fit different drills. There’s sure to be one for your concrete-drilling project.

The Owl Tools bits have standard smooth shanks to fit a regular drill. We didn’t notice any of the bits slipping as we applied pressure while drilling, as some smooth-shank bits tend to do.

Workholding device that affixes to a mill, lathe or drill-press spindle. It holds a tool or workpiece by one end, allowing it to be rotated. May also be fitted to the machine table to hold a workpiece. Two or more adjustable jaws actually hold the tool or part. May be actuated manually, pneumatically, hydraulically or electrically. See collet.

When purchasing and using a drill bit for masonry, there are several important guidelines to follow to ensure a successful outcome.

Hardness is a measure of the resistance of a material to surface indentation or abrasion. There is no absolute scale for hardness. In order to express hardness quantitatively, each type of test has its own scale, which defines hardness. Indentation hardness obtained through static methods is measured by Brinell, Rockwell, Vickers and Knoop tests. Hardness without indentation is measured by a dynamic method, known as the Scleroscope test.

Crystal manufactured from boron nitride under high pressure and temperature. Used to cut hard-to-machine ferrous and nickel-base materials up to 70 HRC. Second hardest material after diamond. See superabrasive tools.

“Nowadays,” Sawicki said, “a lot of high-production cells use robots to take parts out of one chuck and put them into another chuck or onto an inspection table, so you cannot afford to have chips hanging up on the workpiece. The ultimate chip control is using a chipbreaker plus high-pressure coolant at the tip with a coolant-through toolholder, so you’re pretty much guaranteed the chip is going to go into the bed of the machine.”

Hard turning is commonly considered to start with materials of 45 HRC, with a transition zone up to 50 HRC. In that zone, some harder carbide and cermet inserts still work. Coated and uncoated ceramic grades work for a hardness range of 45 HRC to about 60 HRC while CBN inserts are designed for about 50 HRC to 68 HRC.

The KBN05M indexable insert works for high-speed finishing, as well as interrupted machining of hardened steel. Image courtesy Kyocera Precision Tools

Many CBN grades are available and often are designed for continuous-cut steel, heavily interrupted steel or moderately interrupted steel. Once a grade is selected, Coomer said choosing the right edge preparation and hone for the insert can minimize tool wear, lighten tool pressure, improve crater wear resistance and help a tool last longer.

Repeated drilling through dense concrete and stone puts drill bits to the test, often wearing them down quickly. While these drill bits from Makita are more expensive than some masonry drill bit sets, in our tests, their thick tungsten carbide tips held up well for drilling several holes.

Conditioning of the cutting edge, such as a honing or chamfering, to make it stronger and less susceptible to chipping. A chamfer is a bevel on the tool’s cutting edge; the angle is measured from the cutting face downward and generally varies from 25° to 45°. Honing is the process of rounding or blunting the cutting edge with abrasives, either manually or mechanically.

Start by drilling a small guide hole at a low-speed setting for very hard concrete. Once you’ve established a 1/8-inch hole, remove the bit, blow the dust out of the hole, and use a larger bit at medium speed while applying steady pressure. It’s also a good idea to wear hearing protection—concrete drilling can be loud.

Ability of the tool to withstand stresses that cause it to wear during cutting; an attribute linked to alloy composition, base material, thermal conditions, type of tooling and operation and other variables.

“Depending on the specifics of the job, you could source a $500,000 grinding machine, or you could buy a $100,000 lathe and do the same thing with hard turning,” said Travis Coomer, national key account manager for GWS Tool Group in Tavares, Florida. “As long as you can attain all the tolerances given to the part, then it’s absolutely a no-brainer to use hard-turn inserts as opposed to grinding.”

Glenda Taylor is a BobVila.com staff writer with a background in the residential remodeling, home building, and home improvement industries. She started writing for BobVila.com in 2016 and covers a range of topics, including construction methods, code compliance, tool use, and the latest news in the housing and real estate industries.

For most standard bits, you don’t need to use water. However, if you’re using a large hole bit, spraying the surface of the concrete with water can reduce friction and help keep the bit cool as you drill.

Glenda Taylor is a product tester and writer specializing in the construction, remodeling, and real estate industries. She and her husband own a general contracting company, and Taylor is experienced in both residential and commercial building applications. She tests a wide range of power tools as well as other home improvement, household, and lawn-and-garden products.

Before selecting the concrete drill bit sets we wanted to test, we researched more than 20 sets, looking for high-quality bits made from steel with carbide tips. We considered brand to an extent—after all, manufacturers like Bosch and Makita have top reputations for producing high-end power tools and accessories. Still, we didn’t automatically eliminate smaller or niche manufacturers if their masonry drill bit sets were highly rated by customers.

“Certain aluminum oxide ceramic-grade inserts can be used for hard turning, but not all ceramics can hard-turn,” said Brian Sawicki, business development manager for the Northeast region at Tungaloy America Inc. in Arlington Heights, Illinois. “Sometimes you can get away with using ceramic inserts, but you can’t use them in interrupted machining, such as face turning gear teeth, because they will fracture.”

This is the second set of Bosch drill bits to make our lineup, and we found these bits highly efficient. Their four-flute design excelled at ejecting dust and debris as we drilled, which made the drilling process smooth and quick. Their pointed tips kept the bits centered as we started the holes. We were able to drill clean holes in concrete, brick, and even dense stone without problems.

While there is no single chuck or drill head for concrete bits, many concrete bits have a slotted drive system (SDS), which means they have slots on the ends of the shanks for use in rotary hammer drills. SDS bits came out decades ago, and today, an improved version (SDS-plus) is standard on bits for hammer drills. You can still find smooth-shank bits for standard drills and hex-shank bits that will fit standard drills and impact drivers.

An alternative to ceramics and diamond, cubic boron nitride is the second-hardest material, and CBN tools of many grades have been developed for hard turning applications like transmission shafts, constant-velocity joints and toolholders. These inserts are used to finish-turn hard materials and produce fine finishes and tight tolerances, replacing grinding, which takes longer and costs more.

“If the size of the workpiece you’re turning is 1.25" (31.75 mm) or greater, I prefer using an 80-degree rhombic insert with a 32nd nose radius, which is the most common type of CBN insert,” he said. “As the diameter gets smaller, you want to transition into a screw-down positive insert with a front relief angle because it’s more important to be on centerline on smaller components than it is larger components. You’ll be able to hold size and finish better.”

In addition to carbide tips, the EZArc bits have multigrind sharp edges and double-flute design, which make them well suited for drilling in various materials. A hex shank adds even more versatility—these bits are compatible with standard drills and impact drivers. The kit includes five bits: 5/32 inch, 3/16 inch, 1/4 inch, 5/16 inch, and 3/8 inch.

Sharpening drill bits manually with a file or bench grinder is a complicated process. You need a machine specially designed for drill-bit sharpening to do it yourself. It’s usually easier to buy new drill bits.

Chips entangling on workpieces or piling up at the bottom of machine tools can be prevented with the HP-style chipbreaker on the BXA10 range of coated CBN-grade inserts.  Image courtesy of Tungaloy America

Masonry drill bits are specifically designed to tackle stone and can bore through these hard surfaces with ease. Often featuring tungsten carbide tips that can endure drilling through hard stone surfaces, masonry drill bits have wide flutes that allow them to pull away large amounts of material as they drill to prevent debris from jamming the bit. Some bits even use diamond-encrusted blades to cut through this material. They come in a wide range of sizes to suit different needs.

Spending money on specialty concrete bits that see infrequent use may not be the most economical way of expanding one’s collection of drill bits. This EZArc multipurpose bit set offers an excellent alternative. The bits’ design and carbide tips make them suitable for drilling through tile, concrete, and stone plus metal, wood, and even plastic.

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“The outer surface is hard,” he said. “But as you get deeper into the part, it gets softer, and a chipbreaker can help curl the chip to keep it from scratching the softer surface underneath.”

The SHDIATool core bit excelled in our tests. To extend its useful life, users can spray the surface of the material they’re drilling with water, which will help keep the bit cool and reduce friction. This is the bit to have for drilling larger holes in concrete.

Masonry drill bits come in several variations, including rotary percussion, double flute, and saw drill bits. All bit types use large carbide tips that can penetrate stone. Some bits have spear-shaped tips that allow for precision drilling, while others feature a crown-shaped tip that can efficiently grind through masonry.

Cutting tool repeatedly enters and exits the work. Subjects tool to shock loading, making tool toughness, impact strength and flexibility vital. Closely associated with milling operations. See shock loading.

“You’re safe 99.5% of the time running those operating parameters in any hard turning application for most materials above 50 Rockwell C hardness,” he said. “If you’re closer to 50 Rockwell C, start with 500 sfm (152 m/min.). And if you’re hard turning D2 tool steel, start at 300 sfm (91 m/min.) or 350 sfm (107 m/min.).”

Brian Sawicki, business development manager for the Northeast region at Tungaloy America Inc. in Arlington Heights, Illinois, shared best practices for hard turning.