Dormer Pramet A125 8.50 mm x 250 mm HSS ST STRAIGHT SHANK EXTRA LONG SERIES DRILL BS 328

Meet the Dormer Pramet A1258.5X250—an extended-reach solution built for precision and consistency in demanding drilling tasks. Designed to deliver deep-hole performance without compromise, this drill is the go-to choice when you need true straight-line accuracy from start to finish.

Key specifications at a glance

• Diameter and length: 8.50 mm cutting diameter, 250 mm overall length (flute length 200 mm) in accordance with the BS 328 standard.
• Drill point: 118° conical point for positive engagement, stable entry, and clean hole starts that resist wandering.
• Material and finish: Premium High Speed Steel (HSS) with a steam-tempered (steam oxide) finish that helps minimize built-up edge and prevents workpiece material from sticking to the cutting edge.
• Shank and geometry: Straight shank for broad compatibility with common drill chucks and machines; standard spiral flute design for reliable chip evacuation.
• Depth capability: Engineered for 10×D depth-to-diameter performance, enabling single-pass drilling into deep workpieces without frequent retraction or pecking.
• Versatility: Suitable for drilling steels, aluminium, and stainless steels—making it a flexible tool for fabrication, maintenance, and workshop environments.

Why this extra-long drill matters

When drilling deep holes or reaching into recessed features, the A1258.5X250 maintains rigid guidance and minimizes deflection thanks to its elongated form and robust HSS core. The 118° point provides a strong tip that remains easy to re-sharpen, helping you extend tool life and maintain hole quality between regrinds.

Ideal use cases

• Deep through-holes in steel plates, frames, and structural components where standard-length drills fall short.
• Fabrication and maintenance tasks that require long reach without compromising hole accuracy.
• Aluminium and stainless steel drilling in confined spaces where chip evacuation and edge protection are critical.

Practical tips for best results

• Use a steady feed and maintain cooling/lubrication to preserve the sharp edge, especially on stainless steel workpieces.
• Take advantage of the steam-oxide finish to reduce chip adhesion and improve evacuation in long-hole drilling scenarios.
• Inspect the tip after regrinding and restore the 118° angle to keep hole alignment true and surface finish clean.