Bosch Round hex / spline scaling chisel

Why I reached for this chisel

I picked up the Bosch scaling chisel to sort two very different jobs: cleaning mortar off a load of reclaimed brick and breaking out a stubborn shower pan. I wanted a bit that could do controlled surface removal without turning everything beneath into rubble, but still had enough bite to move quickly on tougher patches. Over a couple of weeks, I swapped between a large-spline rotary hammer and a hex-shank breaker, trying the 1-inch and 3-inch blades at both 12-inch and 18-inch lengths. The short version: it’s a tough, straightforward chisel that rewards good technique and tool matching, and it holds up well under daily site use.

Build and options

This is a hammer-steel chisel—no gimmicks, just properly heat-treated steel with a flat scaling edge. Bosch offers it in two shank styles and a few useful sizes:

• Shanks: large spline or hexagon, depending on your hammer.
• Cutting edges: 1, 1.5, 2, and 3 inches.
• Lengths: 12 inches and 18 inches.
• Packs: single pieces and contractor packs (10- and 20-packs, depending on the model).

The breadth of widths is the story here. The 1-inch tip concentrates energy beautifully for tight work (corners, seams, around fixtures), while the 3-inch blade skims over larger surfaces and peels off thin, brittle layers with fewer passes. The 12-inch length gives the best control and feedback; 18 inches buys you leverage and reach when you’re standing off a wall or working across a floor.

I ran the 3-inch, 12-inch-long large-spline option (HS1810) for brick cleanup and waterproofing membrane removal, and alternated between a 1-inch 12-inch and 1-inch 18-inch for the shower work and some concrete scaling. The steel quality is consistent across the pieces I used—edges dressed cleanly on a grinder and didn’t chip out unexpectedly on aggregate.

Setup and compatibility

Fitment is as important as the chisel itself. The large-spline shank locked into my rotary hammer without wiggle, and the hex-shank version seated squarely in a breaker with a positive collar lock. There’s no anti-rotation feature in the chisel itself; you’ll want your hammer in hammer-only mode with rotation disabled for scaling work.

A couple of quick notes before you start:
- Confirm your hammer’s shank style. Large spline and hex are not interchangeable.
- If your hammer tends to “free rotate” the accessory, set it to lock or use a mode that keeps the chisel oriented; wide blades work best when you can control the edge angle.

In use: control trumps brute force

On reclaimed brick, the 3-inch blade at a low, shallow angle lifted mortar beds predictably without gouging the faces. The key was to let the hammer do the work—feather the trigger or pulse the tool rather than burying the tip. The wide edge glided well across flat clay brick. On heavily over-bonded blobs, I would flip to the 1-inch chisel to knock down the high spots, then return to the 3-inch to finish. That combo kept my cleanup quick and preserved the brick’s patina.

For the shower pan, the 1-inch blade proved its worth. It concentrated impact energy enough to fracture the pan and thinset in clean sections, and I could work right up to the flange and framing without collateral damage. With the 18-inch length, I had better mechanical advantage while standing outside the stall, which helped maintain a shallow approach angle; the 12-inch was more nimble inside the footprint. Either way, the chisel moved through the job in under half an hour with a mid-size rotary hammer—no dramas.

On concrete scaling—lifting delaminated patches and old coatings—the 1.5- and 2-inch sizes offer a good middle ground. The 2-inch was a nice balance for removing a brittle parge coat on a foundation wall without undercutting the good material beneath. If you’re chasing spalls, keep your angle as flat as possible and step down to the 1-inch for edges around rebar.

Noise and vibration are a function of the hammer more than the bit, but a sharp, flat edge does reduce bounce and chatter. With a fresh dress, the blade stayed planted and felt predictable. As the edge rounded over, control diminished slightly, which is your cue for maintenance.

Edge retention and maintenance

This isn’t a carbide-tipped accessory; it’s designed to be re-dressed. After a few hours of mixed use on mortar and thinset, I noticed the wide blade just starting to lose its crispness. Ten minutes on a bench grinder brought it back. A few practical pointers:

• Maintain a flat edge with a slight relief on the underside to prevent the chisel from “digging.” Avoid creating a pronounced bevel that will lift the blade.
• Don’t overheat the edge. Grind in light passes and cool between passes. If the steel turns blue at the tip, you’ve gone too hot and softened it.
• Inspect the shank end occasionally. I saw minimal mushrooming on either the large-spline or hex versions after repeated insertions, which speaks well to the heat treatment, but it’s still worth a look.

Used on clean concrete and masonry, the edge holds longer; adhesives, coatings with embedded grit, and accidental encounters with rebar accelerate wear. Plan for periodic touch-ups if you’re doing production-scale floor prep.

Durability and value

The hammer steel builds confidence. I didn’t experience any edge chipping, and the blades remained straight—no twisting or warping—even under heavier blows from the breaker. The 12-inch versions felt stiffer; the 18-inch introduces a bit more flex, but nothing that affected cut quality.

Contractor packs make sense if you’re running crews or if your workflow demands minimal downtime—swapping in a fresh bit mid-day and sharpening the rest in batches is efficient. Singles are fine for the occasional user or small shop. Because they’re regrindable, you’ll get a long life out of each piece if you maintain them.

Limitations and where it doesn’t fit

• Not a demolition chisel: If you’re trying to break through thick, high-strength concrete or encounter heavy aggregate, step up to a point or narrow flat chisel first, then finish with the scaler.
• Wide blades need proper technique: The 3-inch shines on flat, brittle materials. On uneven surfaces, it may skate if you hold too steep an angle or if your hammer allows the chisel to rotate unexpectedly.
• Compatibility check is critical: Large spline and hex options cover many legacy and pro hammers, but they aren’t universal. Make sure you match your shank style before ordering. The hex variant in this lineup is more limited in width options, so plan accordingly if you need wide scraping capability on a hex breaker.

Practical tips for better results

• Use a shallow angle—keep the edge nearly flat to the surface and “peel” rather than “stab.”
• Let the hammer work. Short bursts and moderate pressure preserve both the edge and the substrate.
• Pre-score coatings where possible. Light scoring with a utility knife or a quick pass with a grinder helps the wide blade get under the material.
• Control dust. A vacuum adapter on your hammer or a wet method reduces airborne silica, especially during shower demo and thinset removal.
• Rotate blade sizes. Knock down high spots with 1 inch, then finish with 2 or 3 inches for a clean surface.

Who benefits most

• Masons and remodelers cleaning brick, stone, and block.
• Tile pros removing pans, thinset, and flooring adhesives.
• Concrete repair crews scaling delaminations and parge coats.
• Facility maintenance teams needing a durable, regrindable scraper for recurring tasks.

Recommendation

I recommend the Bosch scaling chisel for anyone who needs a dependable, regrindable scaler that fits large-spline or hex hammers. It’s durable, the size range is genuinely useful, and with basic sharpening it delivers consistent results over a long service life. Choose the 12-inch length for maximum control, keep a 1-inch and a 3-inch on hand to cover detail and bulk removal, and you’ll have most scaling scenarios covered. The only caveat is compatibility—confirm your shank style and width needs before you buy. If that box is checked, this chisel earns its spot in the kit.