Holesaws

A hole saw is the right tool when you need a big round hole and a twist bit just won’t cut it. A hole saw is a saw blade of annular, ring shape, whose annular kerf creates a hole in the workpiece without having to cut up the core material. It’s used in a drill, and it typically has a pilot drill bit at its center to keep the saw teeth from walking.

Here’s why that matters. The fact that a hole saw creates the hole without needing to cut up the core often makes it preferable to twist drills or spade drills for relatively large holes, especially those larger than 25 millimeters, one inch. The same hole can be made faster and using less power. A 4-inch twist bit would stall a pistol-grip drill. A hole saw walks right through.

The single decision that matters most: match the saw to the material. Get that wrong and you’ve got a ruined workpiece and a dead tool. Get it right and you drill clean holes all day.

What a Hole Saw Is and How It Works

The system is simple once you understand the parts. Hole saws consist of a cutting blade, slots, a pilot drill, and an arbor. The arbor is the connecting piece that attaches the hole saw drill bit to the drill chuck.

The cut itself works by perimeter, not by volume. The process begins when the pilot bit drills a small centering hole. As you apply pressure, the circular teeth of the saw engage the material in a rapid cutting motion. Because the saw is only cutting the circumference, it requires significantly less power than a solid bit of the same size. Once the cut is complete, the resulting core remains inside the cylinder.

Those slots on the side of the body aren’t decoration. The slots sitting on either side of the body are there to allow dust and chips to escape from the cylinder as you work, helping to prevent material build-up that can lead to clogging. They also give you a place to jam a screwdriver and pop the slug out.

Depth is the limit you’ll hit first. The depth to which a hole saw can cut is limited by the depth of its cup-like shape. Most hole saws have a fairly short aspect ratio of diameter to depth, and they’re used to cut through relatively thin workpieces. Common hole saw depths are 38, 45 and 60 mm, and for drilling through angled rooftop constructions a depth of 165 and 300 mm is possible.

For diameter, hole saws for use with portable drills are commonly available in diameters from 6 to 130 mm, or in the US, ¼ to 6 inches.

Types and Which Material Each One Cuts

This is the whole ballgame. Four types, four jobs.

Bi-metal is the one most contractors reach for first. A bi-metal hole saw is the most popular and versatile type used in the industry today. The term bi-metal refers to the construction process where two different types of steel are joined together to create a tool that’s both flexible and incredibly hard. Typically, the body of the saw is made from a tough spring steel, while the teeth are made from high-speed steel. This combination creates a saw that can withstand the high heat of friction while resisting the brittleness that often leads to shattered teeth. They’re ideal for cutting through wood, plastic, and thin metal sheets. Their durability and resistance to heat make them a popular choice for general-purpose drilling.

If you’re working stainless, step up to cobalt. Bi-metal cobalt hole saws offer an even greater level of heat resistance. These saws are the workhorses for cutting through stainless steel, sheet metal, and wood. If you’re working with stainless steel, the cobalt-enhanced teeth are almost a requirement to prevent premature tool failure.

Carbide-tipped is for the hard stuff. A carbide hole saw is designed for extremely hard or abrasive materials. A carbide-tipped hole cutter features teeth that are brazed onto the steel body, providing a cutting edge that’s significantly harder than bi-metal. For industrial-scale tasks, a tungsten carbide-tipped hole saw is the preferred choice for cutting through thick plate metal, fiberglass, and even some composites where heat and abrasion would destroy a standard saw. They offer a longer lifespan compared to standard bi-metal hole saws, making them a good investment for heavy-duty applications.

Diamond grit is the only thing that’ll touch tile or glass. When your project involves tile, stone, or glass, a diamond hole saw is the only solution. These tools don’t have traditional teeth; instead, they use diamond grit to grind through the surface. This grinding action prevents the cracking or chipping that often occurs with toothed saws. Designed for ultra-hard materials such as glass, ceramic, porcelain, and stone, diamond grit hole saws use an abrasive rim instead of traditional teeth. The diamond coating allows for precise, chip-free cuts.

Masonry handles brick and block. Masonry hole saws are specifically designed for cutting through brick, concrete, and stone. They typically feature carbide or diamond-tipped cutting edges to handle the tough material. These are commonly used for installing pipes, electrical boxes, and ventilation ducts in masonry surfaces.

Material	Right saw type
Wood, plastic, thin metal, drywall	Bi-metal
Stainless steel, sheet metal	Bi-metal cobalt
Thick plate metal, fiberglass, composites	Carbide-tipped
Tile, glass, porcelain, ceramic, stone	Diamond grit
Brick, concrete, block	Masonry (carbide or diamond)

On the bi-metal grades worth knowing: bi-metal hole saws are suitable not only for metal cutting but also for wood cutting, and they’re available in the two tool steels HSS and HSSE-Co 8, 8% cobalt. They’re best suited for cutting metal and wood. Best results are achieved in steel up to a max 5.0 mm material thickness. With the HSSE-Co 8 you can also cut stainless steel, but only sheets up to a max 1.5 mm. Especially in wood or soft plastics you can achieve a cutting depth of up to 28.0 mm.

The difference in toothing comes down to finish. With easily cuttable materials such as aluminum, wood or plasterboard, the HSS varied toothing clears the cut material better, but compared to the HSSE-Co 8 fine toothing the cut is slightly coarser. The high cobalt content ensures high hot hardness, meaning the steel doesn’t lose its hardness at high temperatures, and the fine toothing ensures smoother running and a better cutting pattern.

Choosing Size, Depth, Tooth Pitch, and Arbor

Start with the fitting, not the saw. Measure what’s going through the hole and add a little clearance so it actually fits.

Match cut depth to material thickness. If the saw is shallower than the material is thick, you’ll be stopping to clear the plug mid-cut — a headache on every hole.

Tooth pitch trades speed for finish. Each hole saw drill bit comes with differing TPIs, Teeth Per Inch. As a rule, higher TPIs result in a smoother finish but take longer to cut. Conversely, a lower TPI will cut the hole quicker but the result won’t be as finessed. Put another way: fine-tooth hole saws with higher teeth per inch provide smoother cuts, making them great for tile and metal; coarse-tooth hole saws with lower teeth per inch cut faster and are better suited for wood and softer materials.

The arbor is where a lot of folks get burned. An arbor connects the drill bit to the drill chuck, and it commonly has a drill bit attached at one end. This bit is used to create pilot holes at the center point of the hole being cut, and pilot holes help to steady the saw during operation to prevent it from wandering.

On big-diameter saws, use a pin-drive arbor. Here’s why. Thread lock can happen when you use a small, non-pin drive, arbor on a large diameter hole saw. The torque from the tool can twist the hole saw onto the arbor, making it challenging to remove. A pin drive arbor applies the torque into the pins instead of the arbor threads, using it to spin the hole saw and prevent the arbor and holesaw from locking together.

A quick-change arbor earns its keep if you swap sizes a lot. Since the hole saw and holder are separate, you can quickly change the different hole saw diameters with the arbor holder.

Western Building Center carries EAB hole saws and mandrels in a range that covers most trade work. The EAB lineup includes mandrel pilot bits in 1/4-inch long and short, plus a carbide pilot bit and a spring-loaded mandrel. Arbor options run from quarter-inch round through 3/8-inch hex shank, plug-out, and quick-change styles. The bi-metal cup sizes step from 3/4-inch up through the 4-3/4-inch range — small enough for a switch box, big enough for recessed lighting and venting.

On kits versus singles: investing in a hole saw kit is almost always more cost-effective than buying individual saws. A comprehensive kit usually includes a piece kit of various diameters that cover the most common trade sizes, and a professional metal hole saw kit will typically include the saws themselves, at least two different-sized arbors, and replacement pilot bits. A 13-piece set running roughly 16mm to 86mm covers the bulk of plumbing and electrical work in one box.

Cutting Technique and Speed by Material

Speed is the difference between a long tool life and a stripped saw. Not all materials are created equal; you must adjust your speed based on your application. When cutting wood, you can run it wide open at 1500 RPM. As you move to harder-to-cut materials, slow down your RPM to let the teeth work optimally and to prevent tool failures like tooth stripping and excessive heat.

Material	Approximate RPM
Wood	up to 1500
Aluminum	~400
Mild steel	~150
Stainless steel	~50

Aluminum is fairly easy to cut, so you can run around 400 RPM. Mild steel requires a little lower RPM, around 150. Stainless steel is hard to cut, so you should run at about 50 RPM. No tach on your drill? Here’s the field trick: if you can still read the logo as the hole saw spins, you are going about 50-60 RPM.

Lubricant buys you tool life on metal. Whenever able, use lubricant to get better life out of your tool. Lubrication helps keep the teeth cool during the cut and prolongs the life of the teeth. For metal, always use cutting fluid to reduce heat and extend the life of the saw. For diamond bits in hard material, switch to water. Very hard materials like reinforced concrete normally should be drilled with water, otherwise the excessive heat generated during the drilling process may cause the diamonds on the core bit to become blunt.

The technique itself is straightforward. Drill the pilot first, then let the saw do the work. Apply steady, consistent pressure and avoid pushing too hard, which can cause the saw to overheat or bind. Drill with light, steady pressure and avoid pendulum movements while drilling.

On wood, back it up. A backer board behind your workpiece prevents blowout where the saw exits. And clamp everything — always clamp the material you’re cutting firmly to a stable surface, which prevents the material from spinning or shifting and can cause injury or an inaccurate cut.

One more on the big saws. The kick-back from a powerful drill may be severe under some conditions, and long side-handles should be used. Anything over 3 inches, put the side handle on. That torque will sprain a wrist if it grabs.

That binding plug is the other common gripe. The core plug often binds inside the hole saw, and often must be pried out after each hole is cut. Sometimes the plug will twist apart mid-cut, creating a condition where the core inside the hole saw spins on the yet-uncut portion of the core still in the workpiece. When it twists, you’ll smell it before you see it.

Frequently Asked Questions

Why use a hole saw instead of a spade bit or twist drill for a big hole? Because it cuts less material and pulls less power. The main advantage is the hole saw’s efficiency, because very little of the total material being removed is actually cut, which reduces the overall power requirement. A 100 millimeter hole would require a huge twist drill or spade drill, unable to be properly driven by a pistol-grip drill, but it can be cut with a hole saw with relative ease.

What hole saw cuts ceramic tile without cracking it? Diamond grit. When your project involves tile, stone, or glass, a diamond hole saw is the only solution. They don’t have traditional teeth; instead they use diamond grit to grind through the surface, and this grinding action prevents the cracking or chipping that often occurs with toothed saws.

Can a bi-metal hole saw cut stainless steel? Yes, the cobalt version, within limits. With the bi-metal hole saw HSSE-Co 8 you can cut stainless steel, but only sheets up to a max 1.5 mm. If you’re working with stainless steel, the cobalt-enhanced teeth are almost a requirement to prevent premature tool failure.

What size hole saw do I need for a standard electrical socket box? For socket and switch work, the common size is 68 mm diameter, often used to drill holes for sockets and light switches and cable ducts in desks or kitchen worktops. Always confirm against the fitting you’re installing.

My hole saw keeps getting stuck on the arbor. What’s wrong? That’s thread lock, and it’s a size mismatch. Thread lock can happen when you use a small, non-pin drive, arbor on a large diameter hole saw. The torque from the tool can twist the hole saw onto the arbor, making it challenging to remove. A pin drive arbor applies the torque into the pins instead of the arbor threads, which prevents the arbor and holesaw from locking together.

Do I need cutting fluid? On metal, yes — it pays off in tool life. Lubrication helps keep the teeth cool during the cut and prolongs the life of the teeth. You can still cut effectively without lubrication, but it will increase the life of your hole saw in certain applications. For diamond bits in hard stone or concrete, use water instead.

What pilot bit goes with a diamond grit hole saw? A different one than your metal saws use. A standard high-speed jobber style bit is the most general purpose. Spade carbide-tipped masonry bits are for going through cinder block and brick. A spring-loaded auto pilot bit works best with diamond grit hole saws.