Bosch 1-1/4 in. StarlockPlus oscillating multi-tool carbide plunge cut blade

I reached for this Bosch carbide plunge blade after finding myself hemmed in by a stud bay with a corroded galvanized line that had to go. A recip saw wouldn’t fit, a grinder would’ve endangered everything around it, and I needed clean, controlled cuts. That job set the tone for how I now use this blade: as a specialized, compact problem-solver for metal and other tough or abrasive materials where precision matters as much as speed.

Setup and compatibility

The blade uses Bosch’s StarlockPlus interface, which snaps solidly onto my StarlockPlus oscillating tool without any fasteners or fiddling. The fit is rock-solid—no slop, no slippage—and the torque transfer is noticeably better than with older OIS-style mounts. Vibration is also lower, which matters when you’re plunging into dense material and trying to keep a tight line.

A key caveat: this is not a universal blade. It fits StarlockPlus and StarlockMax tools. It will not mount to older quick-release or bolt-on oscillating tools that don’t support Starlock. If your tool doesn’t say StarlockPlus or StarlockMax, check compatibility before buying.

Laser-etched markings and the color-coded interface help with quick identification in a crowded blade box, and the labeling held up surprisingly well after heat cycles and debris.

Build and design

At 1-1/4 inches wide with a 1.5-inch immersion depth, the blade is sized for most plunge cuts you’d do in sheet goods, pipe, or through trim when you’re cutting around obstacles. The carbide teeth are arranged to bite into metal and abrasive composites that would quickly dull a bi-metal edge. Compared to bargain oscillating blades, this one feels thicker and more rigid, which helps with tracking on plunge starts and reduces chatter.

It’s a precision Swiss-made accessory, and the manufacturing quality shows in the consistent tooth geometry and clean solder lines. The stiffness and the StarlockPlus mount work together to make plunge starts confident rather than tentative.

Metal cutting performance

On a 1/2-inch galvanized water line tucked between studs, the blade got it done. It wasn’t fast—oscillating blades rarely are in thicker steel—but it was controlled and didn’t skate or grab. I scored a shallow groove, increased pressure gradually, and let the carbide do the work. It’s the kind of cut where your patience is rewarded with zero collateral damage.

After several similar pipe cuts, the edge showed its limits. Carbide excels at abrasion resistance, but it doesn’t love extended, high-heat contact with thick ferrous metal. Expect a handful of serious steel cuts per blade; once the teeth round over or micro-chip, progress slows significantly. For small brackets, nails, screws, and sheet metal, the blade remains efficient much longer. It also impressed me on rebar test cuts. I clamped a piece of #3 and pushed harder than I normally would; it got through in reasonable time. Sparks toward the end are a clue to back off and let the teeth cool—overheating here shortens life quickly.

If you need to cut a lot of thick steel, a grinder or a bandsaw is still the right tool. But for targeted metal cuts in tight quarters—pipes, bolts, embedded fasteners—this blade is absolutely useful.

Cement board and other abrasive materials

Where this blade really shines is in fiber cement siding and cement board. Plunge-cutting clean square openings for exterior boxes is dramatically easier than trying to control a grinder at the edges of a layout line. Dust is far more manageable with the oscillating action, and the kerf is tidy with less breakout at the corners.

I cut multiple outlet and hose bib openings in cement siding and was still on the same blade. The advertised “up to 30× life vs. bi-metal” starts to make sense in these abrasive materials. In my experience, the edge retention in cement board is excellent, and you can push the blade without feeling it glaze over.

It also does well on PVC and similar plastics, though moderate speed and a light touch help keep melting in check.

Wood performance

Yes, it cuts wood, and yes, it will do it in a pinch. But the carbide tooth geometry here is optimized for metal and abrasives, not fast, clean wood cuts. In hardwood and OSB, it tends to burn if you linger or run too fast. If your task is primarily wood—trim undercuts, pocket cuts in subfloor—swap to a dedicated wood or bi-metal wood blade. Where I do use this carbide blade on wood is when I suspect nails, screws, or hidden metal. It takes that abuse in stride and saves the “nice” wood blade for the clean work.

Control, vibration, and accuracy

The StarlockPlus interface is not just marketing speak. Compared to slot-and-bolt mounts, it noticeably reduces vibration. On plunge starts, I can put the tip exactly on the scribe line and ease in without the blade walking. The blade’s rigidity helps keep the kerf straight, especially important in narrow openings where a wiggle can cost you the snug fit around a box or pipe escutcheon.

Noise is typical for an oscillating tool in metal; hearing protection is a must. In cement board, the pitch is less harsh and dust is lower, but I still wear a respirator and eye protection. A vacuum right at the cut helps a lot when working overhead.

Durability and heat management

Carbide’s advantage is life in abrasive materials and survivability when you hit something hard. Its weakness is prolonged heat in thick ferrous metals. A few practical tips that improved life for me:
- Score a shallow trench before committing to a full-depth plunge in metal.
- Use moderate speed; maximum RPMs add heat without a proportional gain in cut rate.
- Let the blade cool between aggressive cuts—two 15-second pushes with a short pause between is better than one 30-second grind.
- Don’t side-load the blade; keep the oscillation doing the work.

Used this way, the blade lasts a long time in cement board and composite siding and remains serviceable through several meaningful metal encounters.

Value

It’s not the cheapest accessory on the wall, and you’re locked into Starlock-compatible tools. But if you own StarlockPlus or StarlockMax, the quick-change convenience and performance justify the premium in the right tasks. For trades that regularly encounter fiber cement and the occasional metal surprise—exterior upgrades, remodel punch lists, service plumbing and electrical—the productivity and control offset the cost. If you only cut wood, save your money and buy a dedicated wood blade set.

Who it’s for

• Remodelers and service pros needing precise plunge cuts in cement board, fiber cement siding, and PVC.
• Plumbers and electricians who occasionally need to cut pipe, bolts, or embedded fasteners in tight quarters.
• Anyone with a StarlockPlus/StarlockMax tool who values low vibration and accurate plunge starts.
• Not ideal for users with non-Starlock tools or for heavy-volume steel cutting.

Pros and cons

Pros:
- Excellent in fiber cement and other abrasive materials; long life there.
- Controlled, precise plunges with low vibration thanks to StarlockPlus.
- Capable of targeted metal cuts where larger tools won’t fit.
- Rigid, well-made blade with clear markings and quick change.

Cons:
- Limited compatibility: StarlockPlus/StarlockMax only.
- Slower in thick steel and will dull after several aggressive metal cuts.
- Not the best choice for general wood cutting; prone to burning if pushed.

Recommendation

I recommend this Bosch carbide plunge blade to anyone with a StarlockPlus or StarlockMax oscillating tool who needs accurate, low-mess cuts in fiber cement and other abrasive materials, plus the ability to make controlled metal cuts in tight spaces. It’s a specialty blade that earns its keep on jobs where precision matters and access is limited. If your work is mostly wood or you’re running a non-Starlock tool, there are better fits for your needs. But for remodelers, service pros, and serious DIYers working with cement siding, cement board, and the occasional pipe or fastener, this blade is a reliable, durable choice that saves time and reduces hassle.