Concrete Dowel Drilling: Rigs, Clearances, Air, and Production Rates
How to size a dowel drilling job: holes, hours, bits, and compressor, what each rig needs in patch width and clearance, and what to bring to the site. E-Z Drill dowel drills sold, rented, and serviced in Newport News and Chesapeake.
When you need a dowel drill
Any time new concrete has to carry load across a joint into existing concrete: full-depth repair patches, lane additions and widening, tying a new apron or slab into an old one, replacing a failed panel. The dowels (smooth bars for transverse joints) or tie bars (deformed, for longitudinal joints) are drilled into the sound face of the existing slab and set with epoxy or grout before the pour. New pavement uses dowel baskets instead and never sees a drill.
The project spec sets the bar, the spacing, and the embedment. For most highway, street, and apron work that's 1 to 1 1/2 inch bars at 12 inches on center, embedded 9 inches, with a drilled hole 1/8 inch over the bar for epoxy. Those three numbers, plus the footage, are all we need to size the drill, the bits, and the air. Bring the drawings or the spec section and we'll do it at the counter.
Estimate a dowel drilling job
Pick the bar, enter the depth, spacing, and footage, and choose the rig. The result is holes, drilling hours and shifts, bits to bring, and the compressor to rent, with a per-hole time you can check against the field times below.
Estimate a dowel drilling job
Holes, hours, bits, and compressorHoles to drill
— diameter × — deep
Planning figure, not a bid. Hard aggregate, old concrete, dull bits, and rebar hits slow drilling and shorten bit life.
Production rates: how fast a dowel drill actually drills
E-Z Drill publishes drilling times from real jobs, all on a 210B SRA with a Chicago Pneumatic 32 rock drill. These are drilling time only; indexing to the next hole, blowing out, and bit changes come on top. The calculator fits these figures (seconds ≈ depth × (0.9 + 1.24 × bit diameter), within about 16% of the published rows) and lets you override.
Published field times
| Bit (inches) | Depth (inches) | Seconds | Job |
|---|---|---|---|
| 5/8" | 16" | 18–20 | Texas |
| 3/4" | 12" | 25–28 | Texas |
| 3/4" | 6" | 15 | Michigan |
| 7/8" | 9" | 15 | Texas |
| 1" | 9" | 18–20 | Florida |
| 1 1/8" | 10" | 21–23 | Oklahoma |
| 1 1/4" | 9 1/2" | 30–33 | Pennsylvania |
| 1 3/8" | 9 1/2" | 21–24 | Pennsylvania |
| 1 3/8" | 10" | 18–26 | Arkansas, Kansas, California, Indiana |
| 1 5/8" | 15" | 48–52 | Georgia |
| 1 5/8" | 9" | 24–26 | Oklahoma |
| 1 3/4" | 10" | 33–35 | Arizona |
Source: E-Z Drill, Drilling Times. Drilling only, on a 210B SRA with a CP 32 motor.
Holes per hour, all in
1 1/8-inch bit, 9 inches deep (a 1-inch dowel), 21 seconds drilling plus 20 seconds handling per hole. Rigs with more gangs drill several holes per cycle.
| Rig | Gangs | Holes per hour | 8-hour shift | Feet of joint at 12-inch spacing |
|---|---|---|---|---|
| 110B / 210B on-grade | 1 | ~88 | ~700 | ~700 ft |
| 210B-2 SRA | 2 | ~175 | ~1,400 | ~1,400 ft |
| 210B-3 SRA | 3 | ~260 | ~2,100 | ~2,100 ft |
| 210B-5 SRA | 5 | ~440 | ~3,500 | ~3,500 ft |
What slows it down: hard river-gravel or granite aggregate, old high-strength concrete, hitting rebar, a dull bit, and air pressure sagging below 90 psi at the drill. What speeds it up: fresh bits, a slab rider on a straight run, and a compressor with headroom.
Rig requirements: minimum patch width, clearances, and weight
The number that catches people out is minimum patch size: the narrowest opening the rig can sit in and still drill the far face, with the back wheel removed and the hole center 3 to 12 inches below the top of the slab. Saw the patch narrower than that and the on-grade rig won't fit. The other fixed clearances are the closest a hole can be drilled to a corner and to the ground.
| Rig | Min. patch (inches) | With dust kit | From corner | Hole above ground | Slab range | Weight | Hose ID |
|---|---|---|---|---|---|---|---|
| E-Z Drill 110B Rental | 36" | 39" | 6" | 3" min. | 15" | 215 lb (306 with dust kit) | 3/4" |
| E-Z Drill 210B Rental | 48" | 51" | 6" | 3" min., to 12" vertical | 6" – 24" | 256 lb (347) | 3/4" |
| E-Z Drill 210B-2 SRA Rental | 48" | 51" | 6" | 3" min. | 6" – 24" | 1,235 lb (1,395) | 1 1/4" |
| E-Z Drill 210B-3 / -4 / -5 SRA Quote | 48" | 51" | 6" | 3" min. | varies | varies | 1 1/4"+ |
Weights in parentheses are with the dust collection kit. We confirm from the spec sheet before you rent or buy.
On-grade rigs (110B, 210B)
Sit on the subgrade or the adjacent slab and drill into the exposed face. One person repositions them by hand, which is why they're the patch-repair rigs. The 110B is the lighter, smaller-bit machine for patches down to 36 inches wide and holes to 12 inches deep; the 210B takes bits to 2 1/2 inches and holes to 18 inches and needs a 48-inch patch. The 210B also drills vertical, with the hole center up to 12 inches off the ground.
Slab riders (SRA)
Ride on top of the existing slab and drill into its edge below, so the far side can be open subgrade; you don't need a patch to sit in, just an exposed slab edge and room on top for the rig. Gangs on the 210B-2 adjust from 12 to 36 inches on center. At 1,235 pounds, the two-gang needs a machine to set it on the slab and move it between runs, and 1 1/4-inch hose.
Dust collection kit
Pulls the cuttings as you drill, which keeps the hole clean for epoxy and keeps silica off the crew. It costs 40 cfm per gang, roughly 90 pounds, and about 2 1/4 inches of depth (18 inches becomes 15 3/4; on the 110B, 12 becomes 9 3/4), and the minimum patch grows by 3 inches.
Air: the part people under-bring
Dowel drills are pneumatic rock drills on a carriage, and they need a lot of air at a steady 90 psi at the drill. Minimum consumption from the spec sheets:
| Rig | Minimum cfm | With dust kit | Rent this towable |
|---|---|---|---|
| 110B | 50 | 90 | 185 cfm |
| 210B | 100 | 140 | 185 cfm |
| 210B-2 SRA | 200 | 260 | 250 (375 with dust) |
| 210B-3 SRA | 300 | 390 | 375 (750 with dust) |
| 210B-4 / -5 SRA | 400 – 500 | 520 – 650 | 750 |
| Minnich A-1CL | 92 scfm at 120 psi | 140 | 185 cfm |
Hose matters as much as the compressor: 3/4-inch inside diameter minimum for the single-gang rigs, 1 1/4 inch for the two-gang, and keep runs short. A long run of 1/2-inch hose will drop a 185 below 90 psi at the drill and the times in the table above stop applying. Rent the compressor with the drill and both come on the same truck with the right hose.
Which rig for the job
| Job | Rig | Why |
|---|---|---|
| Full-depth patches, a few to a few hundred holes | 210B on-grade Rental | Fits a 48-inch patch, drills to 18 inches, one operator. The default. |
| Narrow patches, utility cuts, smaller bars | 110B on-grade Rental | Fits a 36-inch patch, 215 pounds, runs on 50 cfm; bits to 2 inches and 12 inches deep. |
| Lane additions, widening, long tie-bar runs | 210B-2 SRA Rental | Rides the slab, two holes per cycle, gangs set to the spec spacing. |
| Production paving, airport work | 210B-2 / -3 / -4 / -5 SRA or 210 EQ MT Quote | Two to five holes per cycle; equipment-mounted versions ride a skid steer or excavator. |
| Vertical holes, utility and gas work | 20 UTL or 210B in vertical mode Quote | 210B drills vertical to 12 inches off the ground; the 20 UTL is the dedicated utility drill. |
After the hole: setting the bar
- Hole size follows the adhesive data sheet: bar diameter plus 1/8 inch for injected epoxy anchoring adhesive, plus 1/4 to 3/8 inch for grout. Bits are sized to the hole, not the bar.
- Clean the hole: blow, brush, blow. Dust in the hole is the usual reason an epoxied dowel pulls out. The dust kit does most of this as you drill.
- Fill from the back and insert the bar with a twist so no air is trapped; grease the half that will sit in the new pour; hold alignment until the adhesive sets.
We don't stock dowel bars, baskets, or anchoring adhesive. We supply the drill, bits, compressor, saw, and breaker, and can point you to a supplier for the rest.
Full-depth repair: the equipment list
-
Walk-behind concrete saw
Full-depth cuts on the patch boundary. Cut the patch at least 48 inches wide if a 210B is drilling it, 36 inches for a 110B.
Concrete saw rental → -
Breaker or hammer
Pneumatic breakers run off the same compressor as the drill.
Jackhammer rental → -
E-Z Drill dowel drill
110B, 210B, and 210B-2 SRA in the rental fleet; multi-gang and equipment-mounted by quote.
E-Z Drill sales, rental, and service → -
Towable air compressor
185 cfm for one gang; 250–375 for two; 375–750 beyond. Hose included.
Air compressor rental → -
Carbide dowel whirlibits
Sized to the hole. Plan on 150–250 holes per bit and bring a spare.
Bits and parts → -
Mixer or buggy
Small patches are often site-mixed; buggies move ready-mix to a patch the truck can't reach.
Cement mixer rental →
Questions we get at the counter
How wide does the patch have to be for the drill to fit?
How wide does the patch have to be for the drill to fit?
48 inches for a 210B, 36 inches for a 110B, each with the back wheel removed and the hole center 3 to 12 inches below the top of the slab. Add 3 inches if the dust collection kit is on. Saw the boundary with that in mind; a patch cut at 40 inches means a 110B or a hand-held drill.
Can I drill dowel holes with a rotary hammer instead?
Can I drill dowel holes with a rotary hammer instead?
For a handful of holes, yes. Past a dozen or so the rig wins: it holds the bar parallel to the slab so the joint can move, it drills a 1 1/8-inch hole 9 inches deep in about 20 seconds, and nobody is holding 30 pounds at hip height all day. DOT and airport specs usually require a rig.
How many holes a day can one rig do?
How many holes a day can one rig do?
A single-gang 210B on 1-inch dowels runs roughly 85–90 holes an hour all in, call it 700 a shift, which is about 700 feet of joint at 12 inches on center. A two-gang slab rider about doubles that. The calculator above adjusts for bit size, depth, and your own handling time.
What size compressor do I need?
What size compressor do I need?
One gang: a 185 cfm towable, dust kit included. Two gangs: 250, or 375 with the dust kit. Three: 375, or 750 with dust. Four or five: 750. Hose 3/4-inch inside diameter for single gang, 1 1/4 inch for two, kept short. Rent it with the drill and it comes on the same truck.
How many bits should I bring?
How many bits should I bring?
Plan on 150–250 holes per carbide bit, 200 as the guide. Soft limestone aggregate and green concrete run long; river gravel, granite, and rebar hits run short. One spare per 150 holes keeps you drilling.
Do you sell dowel bars and epoxy?
Do you sell dowel bars and epoxy?
No. We supply the drill, bits, compressor, saw, and breaker, and we'll point you to a supplier for bars, baskets, and anchoring adhesive. Bring the spec and we'll size the equipment from it.