DeWalt 1" x 31" x 36" SDS-Max High Impact Quad Drill Bit

Big, deep holes in concrete and stone expose the difference between a bit that merely survives and one that actually helps you get the job done. I’ve been using DeWalt’s SDS‑Max 1‑inch quad‑cutter bit (36-inch overall length) for tie‑backs, dowels, and non-explosive demolition layouts, and it has earned a spot in my kit for long, straight drilling where dust evacuation and tip durability really matter.

Design and build

This is a long, purpose-built bit: 1-inch diameter, 36 inches overall with roughly 31 inches of working length. The SDS‑Max shank transmits plenty of hammer energy and locked solidly in every rotary hammer I tried. The head is a true four-cutter carbide design, not a two-cutter with extra nibs. DeWalt leaves the head “open” with a gullet that channels dust directly into the flutes, and the four-flute helix is elongated to keep spoil moving out of deep holes.

A hardened core runs the length of the body to resist bending and breakage. At 1.24 pounds, it’s not especially heavy for its size, but any 36-inch bit demands respect—start carefully, keep it straight, and let the hammer do the work. The size is etched and easy to read. There’s no case in the box; I’d budget for a PVC tube or a bit roll to keep the carbide from banging around during transport.

Setup and compatibility

SDS‑Max is the key: you’ll want a proper SDS‑Max rotary hammer, not an SDS‑Plus. I ran the bit in medium to large hammers from a few brands without any fit or retention issues. The shank machining is clean and engagement is positive, with no perceptible play. For best results on long holes, I like to:

• Spot the hole with a smaller SDS‑Max masonry bit or a shallow starter cut to prevent skating on smooth concrete or stone faces.
• Start slow to establish a straight path, then let the hammer’s BPM carry the cut.
• Withdraw every few inches to clear dust, even though the flutes do a good job on their own.

If you’re working under a dust control plan, this isn’t a hollow extraction bit, but the open head and flutes pair well with a shroud and a high‑CFM vac. I had good results with a collar-style dust shroud pressed to the surface.

In use: concrete and stone

In cured 4,000–5,000 PSI structural concrete with river rock aggregate, the four-cutter head stays engaged without the catch-and-release you sometimes feel with two-cutter tips. The bit tracks straight, and the full-width carbide corners resist rounding over on the aggregate. Drilling speed is strong for the diameter, especially deeper than a foot, where flute design becomes the deciding factor.

Stone work is where this bit surprised me. On fieldstone and granite boulders for non-explosive demolition grout, the four-cutter head’s stability translated into cleaner holes and fewer stalls. The bit didn’t wander across uneven faces once I established a seat, and it maintained good progress without glazing. I still backed it out regularly to clear dust, but the flutes carried a lot of material on their own.

Rebar is always a question. This is not a rebar-cutting bit, but incidental contact didn’t shatter the carbide or de-braze the head. A light kiss on steel left minor edge wear and a dulled spot on one cutter; as expected, lingering on bar will slow the bit and chew the edge. If you know you’ll hit steel, plan for a rebar cutter or map and avoid.

Speed and chip evacuation

The combination of an open head and four flutes makes a difference in deep holes. Spoil clears faster, which reduces heat and keeps the carbide biting. In side-by-side runs with a similar-length two-flute bit, the DeWalt kept pace near the surface and pulled ahead past 10–12 inches simply because it didn’t choke as easily. You can feel more consistent hammer feedback and less “pumping” to clear the hole.

Practical tip: even with good flutes, deep 1-inch holes benefit from a rhythm—drill 3–4 inches, withdraw, dump dust, repeat. With a vac on a shroud, you can stretch that to 6–8 inches per cycle. Keep the bit straight as you pull back to avoid wallowing the hole.

Accuracy and hole quality

Roundness and diameter accuracy are solid for a hammered masonry hole. The four-cutter geometry tends to cut a more consistent circumference, which helps when you’re installing adhesive anchors or dowels. I measured a handful of test holes and found them slightly over nominal (typical for hammer drilling), with clean walls and minimal breakout at the entry. On through-holes, expect exit spalling; back up the exit face if it’s a finished surface or feather your feed as you approach daylight.

Vibration is well-controlled for a bit this long. In competent hammers, chatter is modest as long as the bit is started square. If you feel a wobble, stop and correct early—long bits amplify small alignment errors.

Durability and wear

The carbide holds up well. After a mix of deep holes in hard concrete and several lines in stone, the cutting edges showed normal wear polishing with minor corner rounding, but no chips or brazing failures. The core stayed straight and I didn’t see heat discoloration on the shank or flutes. If you keep dust moving and avoid hammering against rebar, longevity should be good.

One maintenance habit that pays off: give the flutes a quick brush and a light oil wipe after dusty sessions. It keeps rust off and helps spoil slide on the next use. Also, resist the temptation to pry with the bit to knock out plugs—use a chisel. Side loading is how long bits get bent.

What could be better

• No case. At this length, storage matters. A simple sleeve would protect the carbide from shop rash.
• Not a substitute for dust-extraction bits. The flutes help, but if you’re drilling indoors under strict dust control, a hollow extraction bit is cleaner.
• Long length demands a capable hammer. In smaller SDS‑Max bodies, the bit feels whippy at start-up. That’s physics, not a defect, but it’s worth noting.
• If you routinely hit rebar, you’ll want a rebar cutter in the kit—the quad head is tough, but it’s not designed to eat steel.

Who it’s for

• Concrete crews setting deep anchors, dowel bars, and tie‑backs
• Masons and demo specialists drilling for non-explosive expansion grout
• Electricians and plumbers needing pass‑throughs in thick walls and footings
• Facilities teams dealing with retrofit work in older, hard aggregate concrete

If your drilling rarely exceeds 6–8 inches, a shorter bit is easier to handle. If you need large diameter openings or perfect wall edges, a core bit is the better tool. This 1‑inch by 36‑inch SDS‑Max bit is squarely for deep, straight, hammered holes.

Safety and technique

• Wear eye, hearing, and hand protection. Long bits can whip if misaligned.
• Let the hammer work. Excessive feed pressure slows chip evacuation and heats the carbide.
• Clear dust regularly; pair with a vac and shroud where practical.
• Map rebar when precision matters, or keep a rebar cutter on hand.
• Start square and avoid side loading, especially when backing out of deep holes.

Recommendation

I recommend the DeWalt SDS‑Max 1‑inch quad‑cutter bit for anyone who needs to drill deep, straight holes in concrete or stone with an SDS‑Max rotary hammer. It cuts quickly, stays on line, and—most importantly for long holes—keeps dust moving out of the way so the carbide can keep working. The four-cutter head produces cleaner, rounder holes than two-cutter designs, and the hardened core inspires confidence when you’re 2 feet in and don’t want anything to snap. It’s not a dust-extraction bit, and it won’t replace a rebar cutter, but as a general deep‑drilling workhorse, it’s a dependable choice that balances speed, durability, and control.