Bosch Hex shank screw pilot bit set (5-piece)

I’ve spent enough hours sinking screws into cabinets, trim, and jigs to know that a clean, consistent countersink saves both time and pride. The Bosch pilot bit set has been riding in my drill case for the past few weeks, and it’s become the thing I reach for when I want one-step pilot drilling and a flush screw head without fuss.

What’s in the set

This five-piece kit is straightforward: four combined pilot/countersink bits sized for #6, #8, #10, and #12 screws, plus an Allen wrench for adjustments. All four bits share a 1/4-inch hex shank, which means they drop into keyed or keyless chucks easily, and they also play nicely with quick-change chucks. The cutters are two-flute designs, and the working lengths vary—shorter on the smaller sizes, longer on the larger ones—so you’ve got enough reach for common cabinetry and furniture tasks.

The bit assemblies are modular. The pilot portion is replaceable, and the countersink depth can be adjusted with the included wrench. That combination gives the set more life than a fixed one-piece countersink that becomes landfill the moment you snap a pilot.

Design and build quality

Bosch went with hex shanks across the board to reduce slippage, and that’s not just marketing. In a standard drill chuck, the flat faces keep the bit from spinning under load, and in a quick-change holder the engagement is snug and predictable. The two-flute cutter geometry produces a balanced cut, and in practice I found it evacuates chips reliably in both softwood and hardwood.

The collars are machined accurately, with a set screw that locks down on the pilot bit. The adjustment mechanism is refreshingly simple: loosen the screw, slide the countersink/counterbore collar to your desired position, and retighten. Once locked, the collar stayed put in my testing, even through repetitive drilling sessions.

Setup and depth control

Good countersinks start with a test piece. I set the collar so the screw head lands a hair below the surface for paint-grade work, or closer to flush for clear finishes. The included Allen wrench is the only tool you need for adjustments, and the process is quick—thirty seconds to dial in a depth. For repetitive work, the hex collar doubles as a physical stop, so you’re not relying entirely on feel.

Pro tip: mark the collar position with a fine-line marker if you’re bouncing between depths. It makes returning to a previous setting painless.

Performance in wood

In pine and other softwoods, the Bosch pilot bit set gives clean, chatter-free countersinks when I keep the drill speed moderate. If you lean too hard in resinous woods, any countersink will start to burnish; the solution is simple—let the cutter do the work and clear chips every few holes.

Hardwoods like maple and oak are a tougher test. Here, the two-flute design still cuts crisp edges around the countersink, and the pilots tracked straight without wandering. I had the best results drilling perpendicular to the surface and backing the bit out mid-hole to clear chips on deeper pilot holes. Using a backing board at edges and end grain helps avoid blowout, especially in brittle species.

In plywood and MDF, the set produced clean recesses with minimal fuzzing. On plywood face veneers, I kept the speed lower and eased the bit into the surface to avoid lifting the top ply—again, standard countersink technique, and the cutters responded the way they should.

Performance in plastic and composites

I ran the #8 and #10 through ABS sheet and a piece of acrylic. At slow drill speeds and with light pressure, the pilots cut cleanly and the countersink left a smooth, polished recess with no melting. In fiber-cement backer board, I wouldn’t use this set (wrong tool for abrasive materials), but in common shop plastics and composite woods it’s right at home.

Hand drill vs. drill press

This set is designed for both, and it shows. In a cordless drill, I could move quickly across face frames and carcass sides, getting consistent depths thanks to the collar acting as a stop. The hex shank eliminates the occasional slip you can get with round-shank countersinks.

On the drill press, consistency goes from good to perfect. If you’ve ever batch-drilled hinge screws or cleat holes, pair these with a fence and depth stop for production-level repeatability. The pilots are long enough on the larger sizes to handle thicker stock; for 3/4-inch work you’re squarely in the comfort zone.

Replaceable pilots and maintenance

Eventually, small pilot bits break—that’s just the reality of hidden brads and heavy hands. The replaceable pilot design is the ace up this set’s sleeve. Loosen the set screw, slide out the broken pilot, insert a new one, retighten, and you’re back in business. That extends the life of the cutters and keeps your countersinks consistent across replacements.

After several projects, the cutting edges on the countersink collars still feel sharp, and the finish on the holes remains clean. If you do notice slight dulling down the road, a gentle touch with a small slipstone on the cutting edges can refresh them. Keep the set screw threads clean, and don’t overtighten—snug is enough to prevent slipping without deforming the pilot.

Limitations and small quirks

• Adjustment requires the Allen wrench. It’s quick, but not tool-free. I keep the wrench clipped in the case to avoid hunting for it mid-project.
• This is a wood/plastics set. It’s not intended for metal, and using it there will dull the cutters.
• The smallest pilot is naturally the most fragile. Avoid impact drivers and aggressive feed; a drill gives better control and fewer snapped pilots.
• The four sizes cover the majority of woodworking screws, but if you routinely work with oddball sizes or metric fasteners, plan accordingly.
• The set is excellent at countersinking and will handle shallow counterboring, but if you need deep, plug-style counterbores, a dedicated counterbore and plug cutter are still the better choice.

None of these are deal-breakers for typical shop use, but they’re worth knowing so you can set expectations and avoid avoidable mistakes.

Tips for best results

• Use moderate speed and steady pressure; let the cutters clear chips.
• Back the bit out on deeper pilots to prevent packing.
• Use a backer board near edges and on plywood to avoid blowout.
• Test your depth on scrap before committing to visible surfaces.
• Stick with a drill rather than an impact driver for the smallest pilots.

Who it’s for

If you install cabinets, build furniture, hang doors, or do any trim work, you’ll appreciate the one-step convenience of this set. It’s equally handy for shop jigs and fixtures, where you want screws seated flush so workpieces sit flat. DIYers benefit from the simplicity and built-in depth control, while pros will value the repeatability and the reduced downtime from replaceable pilots.

Recommendation

I recommend the Bosch pilot bit set. It delivers clean, consistent countersinks across wood and plastics, the hex shanks prevent slippage in the chuck, and the replaceable pilot design extends the life of the accessory. Depth adjustment is simple and secure, and the four included sizes cover the fasteners most of us use daily. While the tool-required adjustment and the inherent fragility of the smallest pilot are mild drawbacks, the overall performance, durability, and convenience make this a reliable, work-ready set that earns a permanent slot in the drill case.