Twist drill bit set DeWalt DT4903 — 2 pcs, right-hand rotation, blister pack

DeWalt DT4903 is a two-piece set of right-hand rotation twist drill bits supplied in a blister pack. The bits are designed for drilling high-alloy steels and a variety of metals with tensile strength up to 1100 N/mm², including heat- and acid-resistant steels, cast iron, bronze, welded seams, stainless and chrome-nickel steels. Each bit combines a cobalt-enriched high-speed steel composition with an optimised tip and flute geometry to improve penetration speed and hole quality for handheld or stationary drills.

Advantages

The drill bits contain 5% cobalt for a longer-lasting cutting edge and deliver up to four times the life compared with standard HSS-R bits. A no-walk tip enables easier, more accurate penetration on materials 5 mm and above and produces cleaner, burr-free holes thanks to recessed cutting wings. The optimised tip and flute geometry increase penetration speed and improve chip evacuation, reducing heat build-up during drilling.

Suitable for

• Portable or stationary drilling of high-alloy steels and metals (up to 1100 N/mm²)
• Drilling stainless steel and chrome-nickel alloys
• Working with cast iron, bronze and welded seams
• General metal fabrication and maintenance tasks requiring durable twist drills

Key specifications

• Set size: 2 pieces
• Rotation: right-hand
• Material: high-speed steel with 5% cobalt
• Tip design: no-walk (self-centering) tip with recessed cutting wings
• Shank type: three-sided anti-slip shank on diameters ≥5 mm
• Optimised flute geometry for faster penetration and improved chip removal
• Designed for materials up to 1100 N/mm² tensile strength

How to use

Select the appropriate drill bit diameter for the material and mark the drilling position. Secure the workpiece and fit the bit into the drill chuck, ensuring the anti-slip shank engages correctly for diameters 5 mm and above. Use a suitable drilling speed and apply steady pressure; the no-walk tip assists initial penetration. For best results on hard alloys, use moderate feed and allow the flute to clear chips frequently. Use cutting fluid where appropriate to reduce heat and extend bit life.

Usage recommendations

Use coolant or cutting oil when drilling stainless and high-alloy steels to minimize heat and preserve edge life. For freehand drilling, ensure firm support and a stable stance to reduce risk of breakage; for repeated or deep holes, withdraw the bit periodically to clear chips. Store bits in the blister pack to protect cutting edges and retain size indicators for easy identification.