2021-8.50, 8.5mm, HSS Black Stub Drill

2021-8.50, 8.5mm, HSS Black Stub Drill

$17.94

Description: Black Stub Drill

Brand: Bordo

Material: High Speed Steel (HSS)

Diameter D: 8.5mm

Flute Length: 37mm

Overall Length: 79mm

MPN: 2021-8.50

Quantity Per Package: 5 pieces

Feeds per revolution: 0.18mm

Spindle Speed Aluminum / Brass: 2286 RPM

Spindle Speed Cast Iron: 899 RPM

Spindle Speed Free Cutting Steel: 1611 RPM

Spindle Speed Malleable Iron: 1012 RPM

Spindle Speed Med. Carbon Steel: 1124 RPM

Spindle Speed Stainless Steel: 450 RPM

Spindle Speed Tool Steel: 674 RPM

Spindle Speed Wood / Plastic: 3410 RPM

Out of stock

SKU: 2021-8.50 Category: Tags: , , Brand:

Description

About this item:
  • 8.5mm HSS Black Stub Drill
  • Stub drills (screw machine twist drills) have a shorter overall length than Twist drills for maximum rigidity and longer tool life.
  • 135° Split Point (crankshaft point).
  • Split point is self centering and the short distance from the drill axis to the outer corners results in faster penetration, reducing the need for end thrust.
  • They are designed primarily for machining operations in lathes (screw machines) but can also be used in manual hand held drills.
  • Bordo Stub Drills have two helical flutes with 30 degrees of helix angle. This provides fast chip ejection and very stable drilling operation.
  • Black Finish Stub Drills (also called blue finish) achieve their distinctive colour by steam tempering, a thermal process resulting in a porous tool coating.
  • Black finish tools are generally recommended for ferrous applications where the oxide layer aids chip flow and heat dissipation.

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