DeWalt SDS Plus Stop Bits

I spend a lot of time setting drop-in anchors in commercial slabs, and depth control is the part you can’t afford to get wrong—especially on post-tensioned decks. A dedicated stop bit changes the whole equation. DeWalt’s SDS‑Plus stop bit has become my go-to for 1/2-inch anchor holes because it’s fast, predictable, and takes the guesswork out of embedment depth.

What it is and how it’s built

This is an SDS‑Plus masonry bit with a fixed shoulder that physically stops the drill at a set embedment. The cutting diameter is 1/2 inch, the cutting depth is 13/16 inch, and the overall bit length is about 3-13/16 inches. The tip is carbide for concrete, while the body is a hardened steel. The shank is SDS‑Plus, so it fits any standard SDS‑Plus rotary hammer—no adapters, no wobble. Mine clicked in securely on a Bosch and a DeWalt mid-size rotary hammer.

The shoulder is the defining feature: a broad, machined collar that’s larger than the hole. Once the cutting flutes reach 13/16 inch, the shoulder kisses the concrete surface and stops forward progress. That’s your embedment depth—without fiddling with depth rods, tape flags on a standard bit, or a clamp-on stop collar that likes to walk during hammering.

At 0.22 pounds, the bit is short and compact. That helps with control overhead and limits flex, which matters with larger diameters.

Why a stop bit matters for drop-ins

Drop-in anchors are unforgiving. Too shallow and the setting tool won’t seat the internal plug; too deep and you can lose holding power, or worse, push past a safe zone in post-tensioned slabs. A fixed-depth bit gives you consistency hole after hole. The 13/16-inch depth is right in the sweet spot for many 1/2-inch drop-in styles, with just a hair extra room for dust at the bottom. Always check your anchor manufacturer’s spec, but in my installs this depth lined up with the setting tool and the anchor shoulder exactly as intended.

On post-tension jobs, the peace of mind is real. You should still scan and respect tendon layout, but having a mechanical stop at a known depth is a big safety net compared to trusting a depth rod or manual markings.

Drilling performance

• Speed: The carbide tip bites like a quality 1/2-inch SDS‑Plus masonry bit should. On a medium rotary hammer in hammer-drill mode, I had no trouble producing clean, straight holes in 4,000 psi concrete. The short flute length (about 13/16 inch) isn’t a handicap here because you’re not drilling deep; it actually helps keep the hole straight.

• Hole quality: I got consistent, round holes with minimal bell-mouth at the surface. Because the bit is short and stiff, it’s less prone to walking or flexing. After contacting the shoulder, I ease off the feed pressure and let the hammer do one or two final pulses so the shoulder doesn’t skate or bruise the surface.

• Dust evacuation: There’s only so much flute length to carry chips. I found that a light pecking motion helps; also, pausing right before the shoulder reaches the surface and clearing with vacuum or a blower increases hole quality. The bit works fine with a standard SDS dust shroud—just make sure the shroud lets the shoulder reach the surface.

• Accuracy: With a depth rod, my holes typically vary more than I’d like—rods flex, lock screws slip, and concrete aggregates aren’t uniform. With this stop bit, measured embedment varied by maybe 1/32 inch across a batch. That tracks with what I feel in the drill: the stop is immediate and repeatable.

Ergonomics and control

The compact length is an asset. In overhead work, there’s less lever arm fighting you, and the bit’s shortness keeps it square to the surface. The shoulder also acts like a stabilizer right at the end: once it touches, the bit is centered and won’t “chew” the hole longer.

A tradeoff: the shoulder needs clearance to seat. If you’re right up against a wall, inside a tight channel, or near a protruding edge, the shoulder can interfere. You can’t sneak this into a recess or through a fixture hole smaller than the shoulder, so plan your sequence—drill before mounting plates that would block the collar.

Durability

After multiple dozen holes in cured slab and precast, the carbide has held its edge well. The shoulder picked up a polished ring but hasn’t mushroomed. As with any stop bit, technique matters: don’t lean into the tool after the shoulder hits. Excessive feed pressure at contact will chip the surface or dent the shoulder over time. Let the hammer action do the last fraction of depth and back off the trigger as the collar meets the concrete.

SDS‑Plus shank wear was normal; no galling in the chuck. A dab of shank grease keeps insertion and removal smooth, especially if you’re swapping between bits frequently.

Use cases where it shines

• Repetitive drop-in anchor layouts on decks or cores
• Post-tension slabs where over-drilling must be avoided
• Overhead installs where controlling depth by feel is tough
• Production work where crews need consistent embedment without measuring each hole

Limitations and caveats

• Single-purpose sizing: This version is a 1/2-inch diameter with 13/16-inch depth. If you need different diameters or embedment depths, you’ll need the matching stop bit. There’s no adjustability.

• Clearance: The shoulder prevents getting right up against obstructions. You need a flat landing zone roughly larger than the shoulder diameter.

• No substitute for spec checks: Always verify the required drill diameter and embedment for your specific anchor. This bit’s depth pairs well with many common 1/2-inch drop-ins, but anchor designs vary.

• Material scope: This is a masonry bit. It’s not for drilling steel, tile, or composite decks without appropriate technique and tools.

Tips from the field

• Mark your layout clearly and pre-vac the area. Fine dust can make the shoulder skate at first contact.

• Use a steady feed, then lighten pressure as you approach depth. Let the shoulder land; don’t slam it.

• Clear dust. Even with correct depth, a dusty bottom can keep a drop-in from seating. Blow out and vacuum before setting.

• Keep a standard 1/2-inch SDS‑Plus bit in the kit for tight spots where the shoulder won’t reach, and verify depth with a rod in those rare cases.

• If the surface is rough or broom-finished, a quick pass with a grinder to flatten a small pad improves shoulder contact and hole quality.

Alternatives and comparisons

A depth rod on your rotary hammer is the simplest alternative, but it’s less consistent in real-world concrete and can slip. Clip-on collars emulate this bit’s function but tend to migrate during percussion and often aren’t concentric. A stop bit integrates the stop at the cutting end, so there’s no stack of tolerances.

If you rarely set drop-ins, you might get by with a standard bit plus careful measuring. If you do them regularly—or anywhere near tendons—this is a tool that earns its spot.

Recommendation

I recommend the DeWalt SDS‑Plus stop bit for anyone installing 1/2-inch drop-in anchors with any regularity, and especially for work on post-tensioned slabs. It delivers consistent embedment, speeds up production, and reduces the risk of over-drilling. The fixed shoulder is reliable and well executed, the carbide tip drills quickly and cleanly, and the compact form improves control overhead. Its limitations are inherent to the design—single size and the need for shoulder clearance—but those are easy to plan around. For repetitive anchor work where consistency matters, this stop bit is the right tool.