Hertel 42290 Cobalt Jobber Drill 8.50mm 135 Deg Split Point

Product Description

The HERTEL 42290 is a cobalt jobber-length drill bit designed for drilling into stainless steel, hardened materials, and other tough alloys that wear down standard high-speed steel tooling. Built to M35 cobalt material grade, it carries a 135-degree split point that reduces walking on entry and lowers thrust force needed to start the hole. The 8.50 mm diameter (0.3346 inch) and 4.6063-inch overall length place it in the standard jobber range, making it a direct fit in most drill chucks without an extension. The right-hand spiral flute evacuates chips efficiently and keeps the cut clean through the full depth of the flute.

This drill bit is suited for metalworking applications in maintenance, fabrication, and machine shops where stainless steel, hardened tool steel, and similar high-strength materials are regularly encountered. The heavy-duty grade cobalt construction handles the heat generated in interrupted cuts and work-hardening materials that standard twist drills cannot manage reliably. It is sold individually and is appropriate for both production use and single-repair scenarios on the bench or in the field.

Key Features

• M35 cobalt construction resists heat and wear when cutting stainless steel and hardened materials
• 135-degree split point reduces drill walking and lowers entry thrust force
• 8.50 mm (0.3346 inch) diameter with 2.9528-inch flute length for full jobber-length reach
• Right-hand regular spiral flute promotes efficient chip evacuation
• Straight cylindrical shank fits standard drill chucks without adapters
• Oxide finish provides added surface hardness and corrosion resistance

Compatibility

Designed for use in standard drill chucks and machine tool spindles accepting straight-shank tooling in the 8.00 mm to 9.00 mm diameter range. Primary workpiece materials are stainless steel and hardened materials as specified by the manufacturer.

Installation Notes

This bit is installed and removed by a licensed machinist or qualified trade professional using a keyed or keyless drill chuck sized for straight-shank tooling. Always secure the workpiece in a vise or fixture before drilling; never hand-hold metal workpieces. Use appropriate cutting fluid or coolant when drilling stainless steel to manage heat buildup and extend tool life. Inspect the cutting edges before each use and replace the bit if chipping or dulling is observed.