DEWALT DW5825 Review

Some anchor holes need to go deep — through thick foundation slabs, beneath multiple layers of screed and insulation, or through structural beams where the anchor must reach well below the surface to develop its full holding strength. A standard-length SDS-max bit simply will not reach, and adding a bit extension introduces play, reduces impact energy transfer, and creates another potential failure point. A long-series bit — in this case, a 1-1/4 inch diameter bit with a full 18 inches of usable drilling depth — solves the reach problem directly. The bit body is manufactured as a single piece of steel from tip to shank, so the impact energy from the hammer piston travels straight to the carbide cutting edges without the losses and flex of an extension joint. For structural contractors anchoring into thick concrete elements, a purpose-made long bit means the hole is completed in one pass, to the correct depth, without the compromise and uncertainty of extension-bar drilling.

Extra-long SDS-max bits — typically anything over 450 mm in overall length — are specialised tooling for deep anchor applications. At 1-1/4 inch diameter and 21-1/2 inches overall, the DW5825 is designed for holes that need to reach 400 mm or more below the concrete surface. This depth is encountered in foundation anchor bolts that must extend below the frost line, in structural retrofit drilling where new anchors must bypass existing reinforcement near the surface, and in through-bolting thick concrete elements. The engineering challenge of a long bit is maintaining straightness and concentricity over the full length — a bit that wanders off-axis in a deep hole produces an oval or curved bore that will not accept the anchor correctly and may compromise the fixing's pull-out strength. Quality long bits are straightened and stress-relieved after machining to ensure they drill true.

This review examines a 1-1/4-inch by 21-1/2-inch SDS-max rotary hammer bit from DEWALT, providing 18 inches of usable drilling depth. With 16 reviews averaging 4.5 out of 5 stars, we evaluate its straightness and accuracy in deep-hole drilling, durability of the carbide tip, and its value for structural contractors who regularly need to drill anchor holes beyond the reach of standard-length bits.

The DEWALT DW5825 is an extra-long SDS-max rotary hammer bit with a 1-1/4-inch cutting diameter — approximately 31.75 mm — an 18-inch usable drilling depth, and a 21-1/2-inch overall length including the SDS-max shank. Weighing 1.45 kg and measuring nearly 60 cm in total length, this is a substantial bit designed for deep anchor applications in thick concrete elements. It is sold individually and manufactured from a single piece of steel with a tungsten carbide tip brazed into the cutting head. The SDS-max shank is machined to standard tolerances and fits all SDS-max rotary hammers.

The 1-1/4-inch diameter matches the hole specification for M24 to M30 mechanical and chemical anchors — the sizes used for heavy structural connections where pull-out loads are measured in tens of tonnes. Combined with 18 inches of usable depth, the bit can drill through surface screeds, insulation layers, and deep into the structural concrete below, ensuring the anchor's embedment depth meets the engineer's specification. The single-piece construction from tip to shank is important at this length: any joint or coupling would introduce flex and absorb impact energy, reducing drilling speed and potentially causing the bit to whip or wander off-axis as it advances through dense aggregate. A one-piece bit transmits the hammer's impact directly to the cutting face.

The carbide tip uses a two-cutter design that prioritises aggressive material removal and straightforward re-sharpening geometry — the simpler shape means the bit can be dressed on a diamond wheel to restore cutting performance, extending its service life beyond that of complex multi-cutter tips that cannot be sharpened. In standard concrete without heavy rebar, the two-cutter design drills quickly. When rebar is encountered, the bit may require more care than a four-cutter alternative — the two-cutter geometry is more prone to jamming on steel — but in deep-hole applications, the reinforcement is typically concentrated near the surface and the deeper section of the hole is through unreinforced concrete, so this limitation is less frequently encountered than in shallow structural slab drilling.

The bit's length and weight demand a capable rotary hammer — a machine with at least 8 joules of impact energy is recommended to maintain reasonable drilling speed at 31.75 mm diameter through 400 mm of concrete. Lighter hammers will drill but slowly, and the operator will feel the bit's mass working against the hammer mechanism. The bit should be started carefully to establish a straight entry — at this length, any initial deviation from perpendicular will be amplified as the hole deepens, potentially causing the bit to bind or produce an oval hole. The standard technique is to drill the first 50 mm at reduced speed and pressure, check alignment, and then proceed at full power once the hole is established. Periodically withdrawing the bit to clear debris from the deep hole is essential to prevent dust packing and overheating.

Customer feedback across 16 reviews averages 4.5 out of 5 stars. Users highlight the bit's ability to reach depths that standard bits cannot, and praise the build quality and straightness. Some reviews note that the two-cutter tip dulls faster in heavily reinforced concrete than multi-cutter premium alternatives, which is a fair observation for a bit at this price point. At approximately £84, this is a moderately priced extra-long SDS-max bit — more expensive than standard-length bits but considerably less than the premium four-cutter Bosch alternatives at similar diameters. For the contractor who needs a long-reach 1-1/4-inch bit for specific deep anchor applications, the DW5825 represents a practical balance of reach, diameter, and cost.

The DEWALT DW5825 extra-long SDS-max bit is for structural contractors who need to drill M24-M30 anchor holes 400 mm or deeper through thick concrete elements — where standard bits cannot reach and extensions compromise drilling performance.