Twist Drill Set – 19 pcs

Twist Drill Set – 19 pcs

Specifications

How to choose a drill bit for your job

A number of factors determine which drill bit will be best for an application. These factors include:

1. Type of material to be drilled
2. Drilling speed, and
3. Desired number of holes per bit.

Make sure to select a drill bit with the combination of material, finish, length, and style that will be best-suited for your job.

1. Material

   High-speed steel bits are for general purpose drilling in most material.
   Cobalt steel bits have better heat and wear resistance than high-speed steel bits, so they can run up to 25% faster and have a longer tool life.
   Carbide-tipped bits are more wear resistant than high-speed steel and cobalt steel bits, so they maintain their sharp edges longer for excellent performance on abrasive material, such as plastic. Because they aren’t as brittle as solid carbide bits, they can be used in less rigid setups, such as a hand-held drill.
   Carbide bits are harder, stronger, and more wear resistant than high-speed steel, cobalt steel, and carbide-tipped bits for the highest accuracy and longest tool life. They retain a sharp, hard edge at high temperatures for the best performance on hard and abrasive material. Made of solid carbide, these bits require rigid tool holding to prevent breakage and should not be used in hand-held drilling applications.

2. Finish

   Uncoated bits are good for general purpose drilling of most metal and plastic.
   Black-oxide and black-and-gold-oxide bits produce less friction than uncoated drill bits, so they last longer and can drill at higher speeds.
   Titanium-nitride (TiN) coated bits have added wear and temperature resistance, so they last longer and can drill at higher speeds than uncoated and oxide-coated drill bits.
   Titanium-aluminum-nitride (TiAlN) and aluminum-titanium-nitride (AlTiN) coated bits are the most wear and temperature resistant for the longest life and highest drilling speeds.

3. Length Class
   Jobbers’-length bits have the rigidity and length required for most applications.Maintenance-length bits are shorter and more rigid than jobbers’-length bits but longer than short-length bits. They hold up better than jobbers’ bits when drilling in hard metal. Also known as mechanics’ bits.
   Short-length bits have maximum rigidity for drilling straighter holes than jobbers’-length and maintenance-length bits. Also known as screw-machine and stub-length bits.
   Extended-length bits access hard-to-reach spots and drill deep holes.
   Reduced-shank length bits have a shank that is smaller in diameter than the tip, allowing you to drill large holes with machines that have small-capacity chucks.
   Taper-shank length bits have a Morse taper shank that installs directly into the tapered spindle on machines such as drill presses and lathes.

4. Bit Style

   Spiral-flute bits are the most common bit style and are good for general purpose drilling.
   Parabolic spiral-flute bits have wider flutes than standard spiral flutes for more efficient chip evacuation.

5. Point Angle

   Smaller point angles are better for drilling in soft material; greater point angles are better for drilling in hard material.