Bosch 1-1/4 In. StarlockPlus Oscillating Multi-Tool Carbide Plunge Cut Blade

First impressions and setup

I reached for Bosch’s carbide plunge blade during a remodel that forced me to cut a stubborn galvanized water line in a tight joist bay. A grinder was out of the question and a recip saw would have rattled everything around it. The Bosch carbide plunge blade clicked into my StarlockPlus multi-tool with the usual positive engagement: no screws to fuss with, no slop in the mount. That three-dimensional Starlock interface transmits torque cleanly and noticeably tames vibration compared with older OIS or bolt-on mounts. If you’ve never used Starlock, the convenience and rigidity alone are worth noting.

The blade itself is a compact 1-1/4 inches wide with a 1-1/2-inch plunge depth. It’s Swiss-made, color-coded for quick ID, and laser-etched so you can find the model in a drawer of lookalikes. It’s sold as a single pack, which matters given the premium price.

Note on compatibility: this blade only fits StarlockPlus and StarlockMax tools. It won’t mount to older universal or bolt-on oscillating tools.

Cutting metal in tight quarters

On that 1/2-inch galvanized line, the blade didn’t fly through like a cutoff wheel, but it did the job precisely. I set the tool to a mid-to-high oscillation speed, eased into the plunge, and let the carbide do the work. The cut took patience rather than muscle, which is exactly what I want around finished surfaces and fragile adjacent lines. Because the blade doesn’t kick or skate much, I could work just a couple of inches from a joist without scarring it. After the pipe released, the cut face was clean enough that I wasn’t dressing it with a file.

I’ve also used the blade to nibble through buried finish nails and a handful of rusty screws flush with trim. For those tasks, it’s faster than a bi-metal oscillating blade and far more controllable than a grinder. The 1.25-inch width is a sweet spot: narrow enough to steer, wide enough to keep a straight groove when you’re cutting blind.

If you’re expecting grinder speed on thick steel, you’ll be disappointed. But for embedded fasteners, copper and galvanized tubing, and hardware you can’t reach any other way, this blade is exactly the kind of controlled aggression a multi-tool is meant to deliver.

Rebar and heavier stock

As a stress test, I cut sections of #3 and #4 rebar. On #3, the blade made it through in well under half a minute with steady pressure. There were sparks near the end of each cut—which is typical as the carbide meets heated steel—and tooth wear followed accordingly. It’s doable and safe in cramped spaces where an abrasive wheel would be risky, but I treat rebar cuts as “emergency only” for this blade. It’s not the most economical way to process multiple pieces of heavy steel, and you’ll shorten the blade’s life quickly if you do it regularly.

Fiber cement and masonry-adjacent tasks

Where the Bosch carbide plunge blade shines is fiber cement, cement board, and similar abrasive materials. Plunge-cutting clean square openings in siding for new outlets was both precise and relatively tidy. It’s not dustless—wear a respirator—but it produces far less airborne debris than a grinder and lets you finish corners without overcuts. The carbide teeth hold up well in these materials, and the 1.5-inch plunge is enough to penetrate thicker trims and backing layers in one pass.

For tile prep, the blade works to undercut wood casings and baseboards where a tile saw can’t reach. It’s not a replacement for a dedicated flush-cut saw or a diamond segment blade when you’re actually in tile or masonry, but as a one-blade solution for mixed-material obstacles around a bathroom remodel, it’s very handy.

Wood performance

In clean, soft wood, the blade cuts acceptably, but it’s not a wood specialist. The carbide profile and tooth geometry favor abrasion over chip clearance, so push too hard and you’ll scorch the cut. I use it in wood primarily for small notches, plunge starts, or when I expect to encounter a hidden fastener. For straight wood-only work, swapping to a wood-specific blade is faster and leaves a better surface.

Control, vibration, and heat management

Bosch’s StarlockPlus interface is more than a mounting convenience; it noticeably reduces chatter. The blade tracks well, and I rarely had to fight it to maintain a line. When cutting metal, heat is your biggest enemy. Short strokes with light pressure, a pause to cool, and an occasional dab of cutting fluid will extend the life of the carbide teeth. For fiber cement, slow-to-medium speed and a vacuum nearby keep dust down and teeth cooler.

Durability and life

Bosch claims a much longer life versus standard bi-metal blades. In practice, I’d call the improvement material-dependent. In fiber cement and other abrasive composites, the longevity is excellent—dozens of clean holes and perimeter cuts on a single blade. In thin steel pipe and hardware, you’ll get multiple successful cuts before performance tapers off. In heavy steel like rebar, you can get through, but you’ll pay for it in tooth wear. Once dull, this isn’t a blade you’ll realistically resharpen.

The net: used for what it’s intended—controlled plunge cuts in metal and abrasive building materials—the blade lasts long enough to justify the price. Used as a general-purpose metal demolition blade, it will feel expensive.

Value and who it’s for

If you already own a StarlockPlus or StarlockMax tool and your work involves occasional metal or fiber cement cuts in delicate or tight spaces, this blade is a smart addition to the kit. Plumbers, remodelers, and maintenance techs will appreciate its precision, reach, and the reduced collateral damage compared with spinning tools. DIYers tackling fiber-cement siding or cutting out old galvanized runs will also benefit.

If your oscillating tool doesn’t support Starlock, this blade simply won’t fit. And if your workload skews toward frequent, heavy metal cutting, an angle grinder with bonded wheels or a bandsaw will be faster and more cost-effective.

Small touches

I appreciate the color coding and the clear laser-etched ID—small details that speed up selection on a busy job. The compact width and 1.5-inch immersion depth feel well chosen for real-world plunge cuts, and the Swiss-made fit and finish are obvious in the tooth uniformity and flatness out of the package.

Tips for best results

• Let the oscillation and carbide do the work; heavy pressure overheats the teeth.
• For steel, use medium speed, light pressure, and give the blade a moment to cool between passes.
• Mark your plunge and start with a shallow scoring cut to prevent wandering.
• Swap to a wood blade for long cuts in clean timber to avoid burning.
• Keep a shop vac or dust extractor running when working in fiber cement.

Pros

• Excellent control and low vibration with StarlockPlus mount
• Strong performance in fiber cement, cement board, and embedded fasteners
• Precise plunge cuts in tight spaces with minimal collateral damage
• Durable in abrasive materials compared with bi-metal blades
• Clear identification and color coding

Cons

• Premium price for a single blade
• Limited to StarlockPlus/StarlockMax tools
• Slower and more wear-prone in heavy steel compared with dedicated metal-cutting tools
• Can burn wood if pushed or used for long cuts

Recommendation

I recommend the Bosch carbide plunge blade to anyone with a StarlockPlus or StarlockMax multi-tool who needs controlled, precise cuts in metal and abrasive building materials where space, safety, or finished surfaces rule out a spinning tool. It’s not the fastest option for heavy steel, and it isn’t a wood generalist, but it excels at exactly what a multi-tool is meant to do: clean, accurate plunge cuts in tight spaces with minimal drama. For plumbers, remodelers, and DIYers working with fiber cement, old galvanized lines, or embedded fasteners, it’s a dependable, long-lived blade that earns its spot in the case.