Intro
When a structural engineer specifies M12 or M16 anchor bolts for a critical connection — a steel column base plate, a bridge bearing, a crane rail — the hole must be drilled deep into reinforced concrete, straight and true, to the exact diameter that the anchor manufacturer requires. A 17.5 mm hole at 400 mm depth through concrete that almost certainly contains rebar is not a job for a standard-length bit or a lightweight rotary hammer. It demands a bit with the reach to penetrate the full embedment depth, the shank strength to transmit sustained impact energy without fatigue, and a cutting geometry that stays sharp through aggregate, hard concrete, and the inevitable reinforcement encounters. Bosch's HC5026 Speed-X is a 17.5 mm diameter SDS-Max bit with a 533 mm overall length — a long-reach tool engineered for deep structural anchoring, through-bolting of thick concrete elements, and any application where the hole must go deep into reinforced concrete and the bit must survive the journey.
Generalities
The 17.5 mm (11/16-inch) diameter occupies an important niche in structural fixing: it is the specified hole size for M12 mechanical anchors (sleeve anchors, wedge anchors, and through-bolts), M12 threaded rod in chemical anchoring systems, and M16 bolts in clearance-hole applications. The SDS-Max shank — the larger of the two SDS standards — transmits the 8–15 joules of impact energy from a heavy rotary hammer efficiently into the bit, maintaining drilling speed even as the hole deepens and friction increases along the bit body. Bosch's Speed-X series uses a carbide tip with centric point geometry for accurate starts and a flute design optimised for dust evacuation. The HC5026 measures 533 mm (21 inches) overall with a 17.5 mm diameter — a long bit designed to reach through thick slabs, walls, and foundations to the full embedment depth required for structural anchors.
This overview covers the Bosch HC5026 Speed-X SDS-Max bit: the 17.5 mm diameter and 533 mm length, the applications in structural anchoring and through-bolting, and the practical considerations of deep-hole drilling with a long-reach bit — clearing flutes, managing heat, and matching the bit to an adequately powered rotary hammer.
Description
The Bosch HC5026 Speed-X is an SDS-Max rotary hammer bit with a 17.5 mm (11/16-inch) diameter and 533 mm (21-inch) overall length, providing approximately 480 mm of usable drilling depth. The SDS-Max shank is engineered for heavy rotary hammers in the 5–15 kg class — machines like the Bosch GBH 8, GBH 11, and equivalent professional hammers from Makita, DeWalt, Hilti, and Metabo. The 17.5 mm diameter is the standard hole size for M12 anchor bolts, the most commonly specified structural fixing size for steel-to-concrete connections, balustrade base plates, machinery mounting, and heavy shelving systems. The carbide tip features Bosch's centric point geometry: a sharp centre point that engages first to prevent walking at the hole start, with the main cutting edges following to remove material efficiently. The bit body is hardened steel with a black oxide finish for corrosion resistance and reduced friction.
The 533 mm length is what makes this bit a specialised tool rather than a general-purpose one. Standard SDS-Max bits in this diameter typically measure 340–400 mm overall; the HC5026's extra length enables drilling to anchor embedment depths of 300–450 mm — depths commonly specified for structural connections in seismic zones, high-wind areas, and heavy-load applications where the anchor must reach deep into sound concrete beyond any surface cracking or spalling. The length also allows through-drilling of thick elements — a 400 mm reinforced concrete slab, a 350 mm foundation wall, or a multi-leaf masonry assembly — in a single pass from one side. Drilling technique is critical at this length: withdraw the bit every 100–150 mm of depth to clear the flutes, apply firm but not excessive pressure, and ensure the rotary hammer has adequate impact energy (at least 8 joules recommended) to drive the bit efficiently at full depth. The bit weighs approximately 345 grams.
The HC5026 carries a 4.7 out of 5 star rating from 7 customer reviews on Amazon.fr. At approximately €53, this is a premium consumable reflecting the engineering required to produce a straight, durable bit over half a metre long with a precisely brazed carbide tip. For the structural fixer, steel erector, or concrete contractor who regularly installs deep M12 anchors in reinforced concrete, this bit is the tool that reaches where standard bits cannot — and does so without compromising on hole quality or bit life.
Pros and cons
Pros
- 17.5 mm diameter matches the hole specification for M12 mechanical and chemical anchors — the most commonly used structural fixing size in steel-to-concrete connections, balustrades, machinery mounting, and heavy-duty shelving.
- 533 mm overall length with approximately 480 mm usable depth reaches anchor embedment specifications of 300–450 mm — the deep installations required for structural connections in seismic and high-load applications.
- SDS-Max shank handles sustained impact energy from heavy rotary hammers in the 8–15 joule class — maintaining efficient energy transfer and resisting shank wear even at full drilling depth.
- Centric tip geometry prevents walking at the start of the hole, ensuring the anchor is positioned exactly on the marked fixing point — critical when anchor positions are specified on engineering drawings with tight tolerances.
- 4.7 out of 5 stars from 7 reviews — a well-rated specialised tool with positive feedback from professional users in demanding structural applications.
Cons
- At approximately €53 for a single bit, the cost reflects the specialised long-reach design — users who only need shallow fixing holes will find better value in a standard-length bit at a lower price.
- Requires a heavy rotary hammer with at least 8 joules of impact energy to drive a 17.5 mm bit efficiently at full depth — compact or mid-range SDS-Plus machines cannot use this SDS-Max bit and would struggle with the diameter even if adapted.
- Long-reach bits demand disciplined drilling technique — failing to clear the flutes periodically can compact dust at depth, increasing friction and heat, and potentially seizing the bit in a deep hole.
Use cases
The Bosch HC5026 Speed-X SDS-Max bit is designed for structural steel fixers, concrete anchoring specialists, and heavy construction contractors who install deep M12 anchors in reinforced concrete and need a long-reach bit that reaches full embedment depth while maintaining hole quality and surviving rebar encounters.
Deep Structural Anchoring for Steel-to-Concrete Connections
When engineering specifications call for M12 anchor bolts embedded 300–400 mm into a concrete foundation or column, the HC5026's 533 mm length provides the reach — and the SDS-Max shank handles the sustained impact of drilling at full depth without the shank wear that would degrade an adapted SDS-Plus bit.
Through-Bolting of Thick Concrete Slabs and Walls
Through-bolting a steel base plate to a 350 mm concrete slab requires a hole drilled through the full thickness. The HC5026's length clears the slab in a single pass, and the 17.5 mm diameter provides clearance for M12 bolts with alignment tolerance.
Seismic and High-Load Anchor Installation in Critical Infrastructure
Anchors specified for seismic resistance or high cyclic loading often require deeper embedment than standard fixings. The HC5026 reaches the specified depth while the carbide tip and centric geometry maintain hole diameter and roundness — factors that directly affect anchor performance in dynamic loading conditions.