When it comes to drilling holes in various materials, having the right drill bit is crucial for achieving accurate results. Drill bits are available in different sizes and types, each designed for specific applications. In this article, we will explore the world of drill bits and taps, discussing the importance of tap drill size, as well as providing a comprehensive drill size chart.

What is a Drill Bit?

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A drill bit, also referred to as a Twist drill, is a cutting tool used to create holes in various materials. These bits are available with either straight or tapered shanks, although the most common type has a straight shank. The purpose of a drill bit is to remove material from the workpiece and create a hole of precise dimensions.

Tap Drill Size

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Before performing a tapping operation, it's essential to use the correct tap drill size. Tap drill size refers to the diameter of the drill we should use before tapping. This ensures that the resulting hole is properly sized for the tap, which is crucial for successful threading operations.

ISO and Metric Sizes

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Drill bits are available in both fractional and metric sizes. Fractional sizes are measured in inches, while metric sizes are measured in millimeters. Both systems provide decimal equivalents of the diameters, making it easier to convert between them.

Fractional Drill Size Chart

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The following drill size chart provides a list of standard size drill bits in fractional measurements:

* 1/64 inch (0.016 mm)

* 5/64 inch (0.039 mm)

* 3/32 inch (0.094 mm)

* 7/64 inch (0.109 mm)

* 1/16 inch (0.157 mm)

Metric Drill Size Chart

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The following drill size chart provides a list of standard size drill bits in metric measurements:

* M1.0 (0.039 mm)

* M2.0 (0.079 mm)

* M3.0 (0.118 mm)

* M4.0 (0.157 mm)

Wire Gauge Number Drill Size Chart

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Drill bits can also be identified by their wire gauge number, which is a measure of the diameter of the drill bit in inches. The following chart provides a list of standard size drill bits using wire gauge numbers:

* 60 (0.0595 mm)

* 56 (0.0691 mm)

* 52 (0.0787 mm)

* 50 (0.0862 mm)

Letter Drill Size Chart

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Drill bits can also be identified by their letter designation, which is a measure of the diameter of the drill bit in inches. The following chart provides a list of standard size drill bits using letter designations:

* A (0.060 inch)

* B (0.070 inch)

* C (0.080 inch)

* D (0.090 inch)

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In conclusion, having the right drill bit and tap size is crucial for achieving accurate results in various drilling operations. The ANSI/ASME B94.11M-1993 standard provides a comprehensive guide to drill bits and taps, including fractional, metric, wire gauge number, and letter designations.

When selecting a drill bit, it's essential to consider the material being drilled, as well as the desired hole size and finish. By using the correct drill bit and tap size, you can ensure accurate results and prolong the life of your equipment.

For more information on drilling tolerances and capabilities charts, please refer to our article 'Drilling Tolerances Capabilities Chart.

Drill bit and tap size chart