Non-alloyed construction steel, non alloyed case hardened steel (< 400 N/mm² or < HRB 69) : Most suitable Flatter twist angle creates smaller chippings, ideal for drilling harder steels ie: stainless steel.

Flute geometry - Thunderweb flute form ejects hot chips rapidly. Dissipates heat better increasing life time. Non-alloyed construction steel, non alloyed case hardened steel (400-800 N/mm² or < HRC 21) : Most suitable Kit C ontents: 4 – 12mm Step Drill, 4 – 20mm Step Drill, 2 x 2mm Thunderweb Drill Bits, 2 x 3mm Thunderweb Drill Bits, 2 x 4mm Thunderweb Drill Bits, 1 x 5mm Thunderweb Drill Bit & 1 x 6mm Thunderweb Drill Bit.Repeatable specific diameter holes are easily achieved using the depth bar on your drilling machine. Fully ground drill bits for drilling all metals including stainless steel; can also be used on wood and plastics. Due their stiffness they do not flex or wander on the material making them ideal for spot drilling, this also eliminates the need for pilot drilling.