DEWALT DW5815 Review

For drilling medium-diameter holes in concrete — anchor bolts for structural fixings, through-holes for threaded rod, and penetrations for smaller pipes and conduits — a quality 20 mm SDS-Max masonry bit bridges the gap between light-duty SDS-Plus bits and the heavy 50 mm+ tooling used for large pipe penetrations. The 20 mm diameter is one of the most commonly specified sizes for M16 and M20 chemical anchor bolts, resin fixings, and mechanical expansion anchors used in structural steelwork, balustrade mounting, and heavy equipment installation. An SDS-Max shank provides the larger 18 mm drive interface that handles higher impact energies more efficiently than SDS-Plus, even at moderate diameters where both shank types are available. For contractors who already own SDS-Max rotary hammers, standardising on SDS-Max bits across all diameters — rather than maintaining both SDS-Plus and SDS-Max inventories — simplifies tool management and ensures every bit can be driven by the most powerful hammer on site.

The DeWalt DW5815 is a 20 mm diameter SDS-Max masonry drill bit with an overall length of approximately 330 mm (13 inches). The cutting head is tungsten carbide — the standard material for impact masonry drilling — brazed onto a hardened steel body with a spiral flute design for dust evacuation. The SDS-Max shank is 18 mm in diameter, providing a larger drive interface than SDS-Plus for improved power transmission from heavy rotary hammers. DeWalt's masonry bits are widely used in professional construction, and while this specific model has only 9 customer reviews (averaging 4.1 out of 5 stars), the brand's reputation and the bit's long market presence since at least the early 2000s suggest reliable, if niche, demand.

This review covers the DeWalt DW5815 SDS-Max masonry bit — a 20 mm diameter bit designed for medium-duty drilling in concrete and masonry. We look at the cutting performance you can expect, the compatible hammer classes, and the applications where 20 mm is the right diameter. We also cover the practical considerations of choosing SDS-Max over SDS-Plus for this size range, and identify the users for whom this bit makes the most sense.

The DW5815 is a 20 mm diameter SDS-Max rotary hammer bit with a 330 mm overall length, providing a usable drilling depth of approximately 250 mm to 280 mm depending on the hammer's chuck depth. The tungsten carbide cutting head features a centring point and two cutting edges designed to start cleanly without wandering on smooth concrete surfaces. The spiral flute design evacuates drilling dust from the hole — critical at this diameter because packed dust creates friction that slows progress, generates heat, and accelerates bit wear. The bit weighs approximately 0.61 kg (1.34 pounds), making it manageable for one-handed operation with the hammer's auxiliary handle providing the primary support.

The 20 mm diameter serves several important professional applications. It is the correct size for M16 chemical anchor bolts (which typically require a 20 mm hole), M16 mechanical expansion anchors in concrete, and through-holes for M16 threaded rod used in pipe support bracketry and cable tray suspension systems. It is also commonly used for 20 mm electrical conduit penetrations through walls and for smaller plumbing pipe entries. The 330 mm length is sufficient for drilling through standard brick and block cavity walls in a single pass, and for drilling anchor holes deep enough to meet the embedment requirements of most structural fixing specifications.

The SDS-Max shank on a 20 mm bit is an interesting choice — 20 mm is a diameter where both SDS-Plus and SDS-Max bits are available. The advantage of SDS-Max is the larger 18 mm shank that provides a more robust drive interface and better power transmission from heavy rotary hammers. If you already own SDS-Max hammers for larger diameters, standardising on SDS-Max across your bit inventory means not maintaining separate SDS-Plus bits for the smaller sizes. The trade-off is that SDS-Max hammers are heavier and more expensive than their SDS-Plus equivalents — if you are drilling primarily 8 mm to 16 mm holes with only occasional 20 mm work, an SDS-Plus bit and hammer combination may be more practical.

The bit is compatible with all SDS-Max rotary hammers and performs best with hammers in the 5-joule to 10-joule range — powerful enough to drill efficiently but not so powerful that the bit is overwhelmed. Technique matters: start the hole slowly to establish position, then increase to full speed, and withdraw periodically to clear dust. In reinforced concrete, expect slower progress if rebar is encountered, though 20 mm bits are less prone to jamming on rebar than smaller diameters because the larger cutting head has more mass and rigidity.

The DW5815 carries a 4.1 out of 5 star average from 9 customer reviews — a small sample but generally positive. At approximately €66, it is competitively priced for a branded SDS-Max carbide bit. The bit has been on the market since at least the early 2000s, indicating sustained demand. For professionals who need 20 mm holes in concrete and are already invested in SDS-Max hammers, this is a reliable, no-surprises choice that does exactly what it is designed to do.

The DeWalt DW5815 20 mm SDS-Max masonry bit is best suited for structural steel erectors, mechanical and electrical contractors, and industrial installers who regularly drill 20 mm holes for M16 anchor bolts, through-bolts, and conduit penetrations using SDS-Max rotary hammers.