Bosch 5/8 in. x 13 in. Spline SpeedX Rotary Hammer Bit

Why I reached for a 5/8-in SpeedX bit

I had a run of 5/8-in wedge anchor holes to put into a garage slab and a block wall—nothing exotic, but enough to expose any weakness in a rotary hammer bit. I grabbed the Bosch SpeedX bit in a spline shank, 13 inches overall with an 8-inch working length, and put it through a couple of long days of concrete, masonry, and a little unplanned rebar contact. It left a strong impression: fast, steady, and built to handle real jobsite abuse, with a few caveats around compatibility and depth.

Design and build

The head is where this bit shines. It’s a four-cutter carbide design rather than a traditional two-cutter. In practice, that means fewer snags when you hit aggregates or rebar, better hole roundness, and a more consistent drilling feel. The carbide is well-brazed and the cutting edges arrived sharp and uniform; after use there was predictable wear polishing, but no chipping or chunking.

Bosch uses an active-centering tip that genuinely helps with starts. On dusty slab surfaces where a standard chisel tip skates for the first second, this one bit and held center with minimal persuasion. That matters when you’re laying out anchor holes with tight spacing or working overhead.

The flutes are worth a mention. The front of the flute is deep to carry dust, while the back narrows to reduce friction against the hole wall. It’s a subtle geometry tweak that does two things: keeps the bit from binding as the hole packs up, and reduces heat build-up on long plunges. Combined with a good dust extraction nose, it kept holes cleaner than I expected for a 5/8-in diameter.

The shank is spline, 3/4-inch, so it seats into older-style or heavy-duty spline-drive rotary hammers. Engagement is positive, and I had zero slop or chatter at the shank, even under aggressive hammering. If you’re used to SDS-plus or SDS-max, note the required tool difference; this won’t fit those collets.

Compatibility and setup

This is a spline-shank bit. It won’t fit SDS-plus or SDS-max hammers. If you’re running a spline-drive rotary hammer, you’re good; if not, choose the corresponding SDS version instead. On my spline hammer, the bit locked in with a confident click, and there was no perceptible axial play. I ran it in hammer-drill mode, medium hammer setting, with a dust extraction collar when feasible.

Tip for setup:
- Use a dust extractor on the collar whenever you can. You’ll get cleaner holes and the bit stays cooler.
- For overhead drilling, a short burst at lower RPM helps the centering tip bite before you ramp up speed and impact rate.

Performance in concrete and masonry

In 3,500–4,000 PSI concrete slab, the bit cut fast and smooth. Starts were clean, the bit tracked true, and there was very little wandering. On 6-inch-deep holes for 5/8-in anchors, I could maintain a steady feed without the motor lugging. The four-cutter head really earns its keep when you get into mixed aggregate—it doesn’t “cam” as you pivot pressure; the head keeps chipping around the circumference rather than hammering two edges.

In CMU and brick, the SpeedX was almost effortless. The centering tip grabbed the face of block cleanly and didn’t blow out the entry edge. For through-holes in block, I saw predictable exit spall, but less than with some two-cutter bits. A light feather on the last half inch helps minimize blowout.

I did clip light rebar once. The bit didn’t stop dead or hook badly; I could feel the head working around the steel. That’s typical of a four-cutter geometry: it won’t slice through heavy bar, but it’s less prone to sudden, wrist-jarring binds. After hitting steel, I inspected the cutting edges—no chips, just some polished facets.

Vibration felt controlled. Obviously, the hammer dominates the feel, but the bit’s balanced head and flute design kept chatter low, even in overhead drilling where side-loads creep in.

Dust evacuation and heat

Flute capacity on a 5/8-in bit matters. The SpeedX flutes clear dust effectively, especially when you pull out periodically. With a vac, I rarely had to “peck” the hole; I could keep consistent pressure and let the extractor keep pace. In damp concrete, dust turned to paste, and I needed more frequent withdrawals—par for the course. I never smelled that “hot binder” odor that signals an overheated head, and there was no blueing on the shank after multiple continuous holes.

Hole quality and tolerance

For anchor work, diameter consistency is everything. After a day of drilling, wedge anchors seated with the right level of resistance—snug, not forced. I checked a few hole diameters with pin gauges; they were round and within a reasonable tolerance for 5/8-in anchors. The four-cutter design makes a difference here: two-cutter bits can oval out holes, especially if you lean the hammer. With this head, holes stayed truer.

Entry edges were crisp in concrete. In block, the bit benefitted from that centering tip—clean starts, minimal face chipping. For clean exit holes, I like to back the wall with a sacrificial board; the bit’s geometry doesn’t eliminate breakout, but it reduces it.

Durability

I put a decent workload on the bit: anchors in slab, ledger bolt holes in a block wall, and a handful of deep pilot holes where the full 8-inch working length was used. The carbide edges showed wear polishing but no cracking or chunking, and the braze lines stayed intact. The shaft remained straight with no noticeable runout increase.

If you’re drilling dozens of rebar strikes per day, you’ll eventually nick any head. For typical anchor work with occasional bar contact, this bit holds up well. The German manufacture shows in the uniform braze and precise head casting.

Handling and usability

The 13-inch length provides good clearance over dust boots and forms, but remember the working length is 8 inches. If you need deeper than that, step up to a longer bit or a different shank system. The narrower back flute does reduce friction; you can feel the bit “float” a little easier in the hole on withdrawal. That also means it sheds dust better on the way out, so clearing is quicker.

Balance is good for overhead drilling. The bit isn’t front-heavy, and it doesn’t whip when you reposition the hammer. The spline engagement transfers torque smoothly, so there’s less of that on/off jolt when you encounter aggregate.

Limitations

• Shank type: Spline only. If your hammer is SDS-plus or SDS-max, this won’t fit.
• Depth: 8-inch max drilling depth. Enough for most 5/8-in anchor work, but not for deeper penetrations.
• Rebar: Four-cutter helps with incidental contact, but it’s not a rebar-cutting bit. Plan accordingly if you know you’ll cross steel frequently.

Tips for best results

• Let the centering tip establish the start at lower RPM, then bring up speed and hammering.
• Withdraw every 1–2 inches in deep holes if you aren’t using extraction; with a vac, you can maintain a steady feed.
• Keep the bit perpendicular—four-cutter heads reward a straight stance with better hole roundness.
• Don’t water-cool; these are meant to run dry. Keep chips moving and the bit stays cool enough.

Who it’s for

Contractors, facilities teams, and concrete specialists running spline-drive hammers who need reliable 5/8-in anchor holes in concrete, masonry, and brick. If you’re a DIY user with an SDS-plus rotary hammer, you’ll want the SDS version instead; the performance benefits won’t matter if the bit doesn’t fit your tool.

Value

Given the drilling speed, hole quality, and durability I saw, the SpeedX offers solid value. It’s not the cheapest way to make 5/8-in holes, but it saves time, keeps anchors within tolerance, and shrugs off incidental steel contact better than basic two-cutter bits. For anyone billing time on anchor layout, that matters more than a few dollars on the bit.

Recommendation

I recommend the Bosch SpeedX 5/8-in spline bit for anyone with a compatible spline-drive rotary hammer who needs consistent, fast holes in concrete, masonry, or brick. The four-cutter head, active-centering tip, and effective flute design deliver clean starts, true holes, and steady progress, while the carbide holds up across a full day’s work. The main caveat is compatibility: if you don’t run a spline hammer or you need deeper than 8 inches, choose a different shank or length. For the target user, though, this bit earns a spot in the case.