Concrete Core Drill Bit: Wet, Dry, Diamond, Carbide, SDS-Max

A core bit is a hollow tube with cutting teeth on the rim. It cuts a ring and leaves a plug of concrete, the core or slug, inside the tube. People call it a core drill bit, a coring bit, a concrete hole saw or a core barrel. Most holes it makes are on someone's penetration list: a size, what passes through, and the slab or wall it goes through. This guide works the same way. Bring one hole, leave with one bit.

Every number below is a store price or a maker figure, dated.

What is a core drill bit, and which kind do you need?

A core drill bit cuts a round hole larger than about 1 in. by grinding or chipping a thin ring instead of the whole hole. There are three kinds for concrete, and the drill you own decides between them before the concrete does.

Trait	Wet diamond core (ITM KDX)	SDS-Max one-piece carbide core	SDS-Max modular carbide core
Drill	Core rig or handheld core motor; an SDS-Plus hammer through an adapter, rotation only	SDS-Max rotary hammer, hammer on	SDS-Max rotary hammer, hammer on
How it cuts	Diamond segments grind	Carbide teeth chip	Carbide teeth chip
Water	Yes. ITM: "Use With Water"	No, dry with dust extraction	No, dry with dust extraction
Rebar	Yes. ITM rates it for reinforced concrete	No rebar rating from ITM. Move the hole	No rebar rating from ITM. Move the hole
Cut per pass	14 in.	3 in., then break the slug	3 in., then break the slug
Sizes we stock	1 to 12 in.	2 to 6 in.	1-1/2 to 5 in.
Price range	$69.26 to $587.35	$204.36 to $574.27	$99.26 to $355.34, plus a one-time kit

All three are ITM. The KDX wet diamond cores are 15-3/4 in. long with 10 mm tall segments. The SDS-Max core bits come as one piece with the pilot drill included, or as a modular core that screws onto a tapered SDS-Max extension. For tile, glass or a stone countertop, you want a different bit: see the tile and stone diamond cores.

Wet or dry: what does the water actually do?

Water does three jobs for a diamond core bit: it cools the segments, it flushes the ground concrete out as slurry, and it keeps silica dust out of the air. Without it, a wet bit overheats, the bond smears over the diamonds, and segments can come off. MK Diamond lists "Not enough water to properly cool the bit" as a cause of lost segments.

Keep the water and the rotation on the whole time the bit is in the hole. Norton's coring instructions say: "Do not stop the flow of water or the rotation of the core bit." You want a thin, gray slurry coming out of the cut, not clear water and not paste.

Dry coring belongs to carbide cores in a rotary hammer. ITM's one-piece and modular SDS-Max cores cut concrete, brick, block and stone dry, with the hammer on. Dry diamond cores exist too, but most makers limit them to block and brick. Hilti, for one, rates its dry masonry core bit "in abrasive brick and concrete block only."

The dust rules are different for wet and dry. OSHA's silica standard for construction, 29 CFR 1926.1153, gives a Table 1 entry for each:

• Rig-mounted core drills: "Use tool equipped with integrated water delivery system that supplies water to cutting surface."

• Handheld drills, rotary hammers included: a shroud or cowling with a dust collector that has a filter of 99% or better efficiency and a filter-cleaning mechanism, and "a HEPA-filtered vacuum when cleaning holes."

Handheld wet coring isn't one of the Table 1 tasks, so check it with your company's exposure plan. That is the rule's wording, not our ruling on your job.

Diamond or carbide: will a concrete core bit drill through rebar?

A diamond core bit will drill through rebar. A carbide core bit is the wrong tool for it. Diamond grinds steel the way it grinds stone, and ITM rates its KDX cores for reinforced concrete. Carbide teeth are made to chip concrete under hammer blows. Steel doesn't chip, so the teeth chip instead.

When a diamond core hits rebar, the feed gets harder and the slurry turns rusty. Ease off the pressure and keep the water up until you're through the bar. MK Diamond lists "Steel reinforcing rod" as a cause of lost segments when the feed stays hard.

When a carbide core hits rebar, stop. Pull the bit, look at the teeth, and either move the hole a few inches or finish it with a diamond core. For anchor-size holes through a bar, an SDS-Max rebar puncher runs in hammer mode. Our rebar drill bit guide covers those.

Scan before you core. Ground-penetrating radar (GPR) finds rebar, conduit and post-tension tendons. In a post-tension slab, cutting a tendon is a structural and safety problem, not a broken bit, and tendons sit inches away from where the drawings show them. Coring a post-tension slab takes the engineer's sign-off.

SDS-Max core bit: one-piece or modular?

Hole line: 2-3/4 in. · sump discharge · 8 in. block wall · SDS-Max · dry

For one hole size, buy the one-piece SDS-Max core bit. For a set of sizes, buy the modular system. The one-piece bit comes with its pilot drill. The modular core needs an 8 in. tapered SDS-Max extension, A-taper pilot drills and an ejector key, bought once and shared by every core in the set.

Modular kit part	SKU	Price	Buy at least
8 in. SDS-Max tapered extension	720MAX008	$71.24	1
3/8 x 5 in. A-taper pilot drill	721PD0385	$11.86	5
Ejector key	722EJ0001	$8.64	5

The first kit costs $173.74. For a single 2 in. hole, the one-piece 880SL1035 at $204.36 beats the modular 2 in. core plus kit ($303.00) by $98.64. Add a second size and the two are even: 2 in. plus 4 in. costs $567.67 in one-piece bits and $569.44 modular. From the third size on, modular wins. A 2, 3-1/2 and 4 in. set costs $881.74 one-piece and $776.23 modular.

Both systems cut about 3 in. before the core has to come out. ITM prints "3" Cutting Depth Before Core Removal" for its one-piece bits. Its modular routine is:

1. Drill with the pilot until the core is 3/8 in. into the concrete.

2. Pull the pilot out and keep drilling to about 3 in.

3. Break the core loose inside the bit with a chisel and clear it.

4. Repeat until you're through.

ITM warns that drilling without the pilot puts "excessive pressure on the taper shank system," and that breaks from it aren't covered.

The SDS-Max core bits take an SDS-Max hammer. An SDS-Plus hammer can't run them. Our SDS Plus vs SDS Max guide puts the line at 1 in.: SDS-Plus up to 1 in., SDS-Max above that and for coring.

Core drill bit sizes: what hole does the pipe need?

Size the core bit to the pipe's outside diameter, not its trade size, then add clearance. A "2 in." PVC pipe is 2.375 in. outside, so a 2 in. bit won't pass it. Add about 1/4 in. total for a snug hole you'll caulk, and about 1/2 in. for grout or a link seal. For a fire-rated floor or wall, the listed firestop system sets the gap, and so the hole.

Passes through	Outside diameter (in.)	Snug hole: wet diamond	Snug hole: SDS-Max one-piece
1 in. EMT	1.163	KDX-25, 1-1/2 in.	—
1-1/2 in. EMT	1.740	KDX-04, 2 in.	880SL1035, 2 in.
2 in. EMT	2.197	KDX-05, 2-1/2 in.	880SL1055, 2-3/4 in.
1-1/2 in. PVC or rigid	1.900	KDX-05, 2-1/2 in.	880SL1055, 2-3/4 in.
2 in. PVC or rigid	2.375	KDX-06, 2-3/4 in.	880SL1055, 2-3/4 in.
3 in. PVC drain	3.500	KDX-08, 4 in.	880SL1115, 4 in.
4 in. PVC drain	4.500	KDX-11, 5 in.	880SL1135, 5 in.
6 in. PVC drain	6.625	KDX-20, 8 in.	—
Foundation wall anchor rod	3 in. hole (maker spec)	KDX-07, 3 in.	880SL1075, 3-1/4 in.

The common miss is the 4 in. drain. Its pipe is 4-1/2 in. outside, so a 4-1/2 in. bit leaves no gap at all. Use the 5 in. KDX-11. Wall anchor makers such as Chance and Helitech call for a 3 in. hole through the foundation wall.

Here is every size we stock in all three families, priced per bit. Swipe the rail to compare one size, or build a set to see when the modular kit pays off.

Size (in.)	KDX wet diamond	SDS-Max one-piece, 12 in.	SDS-Max one-piece, 22 in.	SDS-Max modular core
1	$69.26	—	—	—
1-1/4	$79.09	—	—	—
1-1/2	$81.81	—	—	$99.26
1-3/4	$84.54	—	—	—
2	$91.63	$204.36	$239.71	$129.26
2-1/2	$99.26	—	—	$140.13
2-3/4	$114.54	$232.14	$267.17	—
3	$122.17	—	—	$183.32
3-1/4	—	$290.65	$322.72	—
3-1/2	—	$314.07	$343.49	$206.79
4	$159.99	$363.31	$387.76	$266.44
4-1/2	$200.71	—	—	—
5	$216.42	—	$457.36	$355.34
6	$249.00	—	$574.27	—
6-1/2	$283.22	—	—	—
8	$417.74	—	—	—
10	$458.03	—	—	—
12	$587.35	—	—	—

Price per bit, store prices of November 12, 2026. Every core is sold singly. The modular cores also need the one-time kit above.

Which drill runs a core bit, and what adapter does it need?

A core rig or a handheld core motor runs the KDX through its threaded end. ITM's catalog puts a 5/8"-11 thread on the 1 in. KDX and a 1-1/4"-7 thread from 1-1/4 in. up. Those are the two standard core-drill threads. An SDS-Plus rotary hammer can turn a KDX through an adapter, with the hammer off.

Adapter	SKU	Price	Buy at least	Fits
SDS-Plus to 5/8"-11	ADA002	$29.81	2	1 in. KDX-01 on an SDS-Plus hammer, rotation only
SDS-Plus to 1-1/4"-7	ADA003	$41.90	1	KDX 1-1/4 in. and up on an SDS-Plus hammer, rotation only
5/8"-11 to 3/8" hex	PAD-5811	$12.81	4	1 in. KDX-01 in a 1/2 in. drill chuck

Never put a diamond core in hammer mode. The blows crack the segments. And mind the size: an SDS-Plus hammer or a 1/2 in. drill doesn't have the torque for a big core, and a bit that binds will spin the drill, not the bit. Above 2 in. in concrete, use a core motor with a clutch.

Diamond cores need the right speed: small bits fast, big bits slow. MK Diamond's chart gives an ideal of about 1,600 RPM for a 2 in. bit, 1,050 for 3 in., 800 for 4 in., 560 for 6 in. and 265 for 12 in. Our drill speed chart explains why heat, not speed, is what kills a bit.

How deep can a core drill go?

Hole line: 6 in. · chilled-water riser · 14 in. deck · core rig · water

A KDX wet diamond core cuts 14 in. in one pass, which covers most slabs and walls. Past 14 in., a diamond core needs a threaded core extension. An SDS-Max carbide core cuts 3 in. at a time. Its total reach depends on the bit's length and the extension behind it.

Bit	Cut per pass (in.)	Reach (in.)	Past that
KDX wet diamond	14	14	A 1-1/4"-7 core extension
SDS-Max one-piece, 12 in.	3	about 8	The 22 in. bit of the same size
SDS-Max one-piece, 22 in.	3	about 18	An X-Tendr extension
SDS-Max modular core on the 8 in. taper	3	about 8	18 in. taper (720MAX018)

Reach for the SDS-Max bits is our estimate: overall length less the shank in the chuck. ITM doesn't print it.

For SDS-Max bits, the X-Tendr system adds length behind any SDS-Max core bit. ITM's rule is that the bit must be at least 1-1/4 in. across so the adapter follows it into the hole. The XT6700 adapter is $261.22 and the 30 in. XT6702 shaft is $52.67. Our SDS-Max extension and adapter guide walks through it.

In a data hall, structural decks often run 12 to 18 in. and carry dense rebar, so the wet diamond core is the standard choice. Scan first, keep slurry away from live equipment, and size the hole for the sleeve and firestop, not the pipe alone. Hilti, for one, rates handheld coring in steel-reinforced walls to 6 in. and goes to a rig above that. Our data center coring collection gathers the bits for this work.

Why did my core bit stop cutting?

A diamond core bit that stops cutting is usually glazed: the metal bond has worn smooth over the diamonds, so nothing sharp touches the concrete. MK Diamond's causes are too much feed pressure or aggregate too hard for the bond. The fix is to dress it: run the bit a few seconds into a concrete block or an abrasive dressing block until the segments feel sandy again.

Symptom	Likely cause	Fix
Diamond bit spins but won't go down	Glazed segments	Dress it in block; ease the feed
Segment came off	Too little water, or hard feed through rebar	More water; ease off at steel
Core stuck inside the bit	Slurry packed in, or a broken core wedged	Drive it out through the hub; don't hammer the tube
Bit stuck in the hole	Water stopped or the bit tipped	Unplug, then back it out by the thread, never with the motor
Carbide core suddenly stops	Hit rebar or the slug is full	Check the teeth; break the slug every 3 in.

Diamond Products' manual is blunt about the stuck core: "DO NOT hammer on tube." A dented tube grabs every core after it.

Which core bit should I buy for my job?

Find your hole line, then buy the bit in the same row. Each row is a real bit at its store price.

Hole line	Buy	Price	Also needs
1-1/2 in. EMT · 6 in. slab · SDS-Max · dry	880SL1035 2 x 12 in. one-piece	$204.36	Pilot included
2 in. PVC · 8 in. wall · core rig · water	KDX-06 2-3/4 in.	$114.54	1-1/4"-7 core motor
4 in. drain · basement slab · core rig · water	KDX-11 5 in.	$216.42	Scan first if post-tension
Sump discharge · foundation wall · SDS-Max · dry	880SL1055 2-3/4 x 12 in.	$232.14	22 in. 880SL1065 ($267.17) for thick walls
3 in. wall anchors · many walls · SDS-Max	719CB0080 3 in. modular	$183.32	Kit, $173.74 once
6 in. sleeve · data hall deck · core rig · water	KDX-12 6 in.	$249.00	Extension past 14 in.
1 in. hole · slab · SDS-Plus · rotation only	KDX-01 + ADA002	$69.26 + $59.62 (2 adapters)	Water
Through-hole, no core wanted · SDS-Max	950CC7331 1-1/2 x 22 in. tunnel bore	$236.06	One pass, nothing to knock out

Foundation crews will find the wall anchor and sump picks on our foundation repair tools list too. For holes under 1-1/8 in., a core bit is overkill: a masonry drill bit is faster and costs a few dollars.

[DAVID: one first-hand line, for example the coring call you get most, or why a crew should own the bit and rent the motor.]

Core drill bit questions

Are core drill bits reverse threaded?

No. Core bits use standard right-hand threads, 5/8"-11 or 1-1/4"-7, and the motor's rotation keeps them tight. A thin copper ring between the bit and the motor makes a stuck bit easier to break loose.

Should I buy or rent a concrete core drill bit?

Rent the core motor if you core a few times a year, but think about buying the bit. Rental yards often charge for segment wear on top of the day rate, and a KDX bit runs $91.63 at 2 in.

Can a wet diamond core bit be used dry?

Not for long. ITM marks its KDX cores "Use With Water." Run dry, the segments overheat and the bond glazes or lets go. For dry holes, use an SDS-Max carbide core with dust extraction.

Can I use a core bit in a hammer drill?

Only a carbide SDS-Max core, in an SDS-Max rotary hammer, with the hammer on. Diamond cores run rotation only. A three-jaw hammer drill takes neither, except the 1 in. KDX through a hex adapter with the hammer off.

Written by Vanessa at Eldorado Tools from ITM's 2024 catalog (pp. 97–105), MK Diamond, Norton and OSHA 29 CFR 1926.1153 Table 1. Prices are store prices of November 12, 2026. Change log: first published [date].