No.61 - 80 20 Piece Bright Finish HSS Jobber Set

About this item:

• No.61 - 80 20 Piece Bright HSS Twist Set
• Bordo Wire Gauge Quick Silver M2-HSS Twist Drills.
• 118° Split Point (crankshaft point).
• Split point is self centering and reduces the need for end thrust. Friction at workpiece is reduced.
• 118° point angles are ideal for use in materials such as mild steel and cast iron.
• The 118° point creates easily controlled chips which are wide and thin.
• Bright Finish Twist Drills have no surface treatment and are supplied in the as-ground condition.
• These tools are suitable for general purpose use, particularly for non-ferrous applications.
• Gauge size drill calculations are generally made utilising a reference book or table.
• For example, to drill a hole which is 10 thou (thousandth of an inch = .001) bigger than a 1/8? bolt, the user must first work out that 1/8? is 125 thou, so the required hole size is 135 thou. Using a reference table establishes that you would need a number 29.
• Number drill bit gauge sizes are analogous to, but different from, American wire gauge.
• Number gauge is most commonly used from size 80 (the smallest) to size 1 (the largest) followed by letter gauge size A (the smallest) to size Z (the largest).
• Number gauge is actually defined down to size 97, but these smallest sizes are very rarely used.

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