The information provided in this document is provided quot as is quot with no guarantee of accuracy or relevance of the information provided The chart has been developed using various print and on line sources as a primary reference source for students in engineering engineering technology or vocational classes Drill Bit Size 1 4″ 20 Tap 7 13 64″ 1 4″ 28 Tap 3 7 32″ The concept of tapping threads is relatively simple but in practice it can get complicated If the hole is too small the tapping will extend too far into the center making it difficult to screw the bolt into the hole 22 4 2020 nbsp 0183 32 List of Drill and Tap Sizes Drill Bit Sizes Metric The drill size chart contains tools up to 1 5 inches in diameter but larger tools are also commonly used Drill Bit Sizes English Tap Sizes Metric For each thread count the equivalent thread pitch is provided and for metric taps the approximate thread count is shown based on the pitch Drill Bit Size Chart This chart shows decimal inch equivalents for fractional inch wire size letter size and metric drill bits up to two inches in diameter SizePlease send corrections and comments to eng form Last Updated on 05 01 200305 01 2003

5 4 2019 nbsp 0183 32 More About Drill Bit Sets and Sizing Some other helpful information to help you in your knowledge of drill bit sizes Fractional Sizing Fractional sizing uses whole half 1 2 quarter 1 4 eighth 1 8 sixteenths 1 16 and sixty fourths 1 64 Tap size Drilling chart provides a list of standard size taps specifying the diameter and thread spacing for fractional metric and screw sizes 66 rows nbsp 0183 32 1 4 quot 20 UNC 5 1594mm 203125 quot 13 64 quot 5 1816mm 204 quot 6 5 2197mm 2055 quot 5 There is nothing more aggravating when you just don t know what size drill bit to use for a pilot To help my readers out I thought I would add this quick reference chart This should help whenever you run into a situation you need to drill a pilot hole and are not sure the size bit I also have included the chart for drill bit size per tap size 19 1 2020 nbsp 0183 32 To Tap This Size Screw Or Bolt Use This Drill Bit Closest Fractional 1 4 28 NF 3 7 32 quot 1 4 32 NEF 7 32 quot 7 32 quot

Flute Length 2 3 4 in Maximum Drilling Depth 1 in Helix Angle 28 Degrees Cutting Direction Right Hand Spiral Direction Right Hand Shank Type Machining Straight Shank Dia 1 4 in Shank Length 1 1 4 in Overall Length 4 in Depth Dia Ratio 4xD Drill Length Class Jobber Length Drill Point Length 0 0751 in Drill Bit Grouping Individual Drill Bits On This Page Jobber Drills Cobalt Jobber Drills Long Series Drills Reduced Shank Drills HSS Reduced Shank Drills Panel amp Rivet Drills Step Drills 1 1 8 quot 28 57mm 152 86 1 2 quot D1882858 1 3 16 quot 30 16mm 152 86 1 2 quot D1883016 1 1 4 quot 31 75mm 152 86 1 2 quot D1883175 HSS Reduced Shank Drills Diameter OAL mm Shank Drill Bit Conversion Chart Numbers amp Letters Wire Gauge Drill Size Comparison Chart 55 0 052 1 321 28 0 1405 3 569 1 0 228 5 791 Z 0 413 10 49 54 0 055 1 397 27 0 144 3 658 Metric Drill Size Conversion Chart Equivalent Drill Size Hole Diameter Equivalent Drill SizeCobalt 1 4 quot x 28 Threaded Shank Angle Bit This threaded shank angle bit is designed to fit an aircraft angle drill for more clearance in tight spaces Buy in a quantity of 50 for a savings Features Drill in tight quarters with this one inch length drill bit produced from industrial grade NAS 965 cobalt steel Drill Size Chart The drill size chart provides a list of standard size drill bits in several measurement systems including fractional metric wire gauge number and letter The decimal equivalents of the diameters are shown in both English and Metric units Fractional sizes are measured in inches while metric sizes are measured in millimeters

40 098 1 4 28 THREADED DRILL BIT COBALT 1 quot LONG December 19 2021 Q amp A Submit Please note Aircraft Spruce s personnel are not certified aircraft mechanics and can only provide general support and ideas which should not be relied upon or implemented in lieu of consulting an A amp P or other qualified technician How to Drill amp Tap for a 1 4 20 Bolt Measure the location needed for the 1 4 20 tapped hole Set the point of the center punch on the location of the hole to be tapped Insert the drill bit into the drill Apply pressure to the drill Insert the 1 4 20 tap into the to calculate tap drill size for acme taps the magic formula step 1 1 Divided by TPI threads per inch step 2 subtract this amount from the OD for pitches 10 and greater always add 005 quot for the drill size for pitches less than 10 TPI take the amount from step 1 and multiply x 05 5 and add this to the drill size ANSI B94 11M 1979 sets size standards for jobber length straight shank twist drill bits from 1 64 inch through 1 inch in 1 64 inch increments Decimal drill bit sizes written in number with 4 decimal places equivalent to fractional inch drill bit sizes List of Drill and Tap Sizes The IRWIN HANSON 1 4 quot 28 NF Tap and No 3 Drill Bit is ideal for creating precise holes and 28 clean threads per inch in metal for general purpose drilling The drill bit is constructed of high speed steel for fast drilling while the tap is crafted of high carbon steel for durability

Head height 1 quot 3 8 quot side to center Accepts 1 4 quot 28 threaded bits 1 4 quot capacity 7 quot overall length Heavy duty economical drill attachment Has 1 4x28 internal thread for use with standard threaded drill bits or miniature chucks SDS Plus Drill Bits SHOCKWAVE™ Multi Material Drill Bits SDS Max Drill Bits Spline Drill Bits Hammer Drill Bits Vacuum Drill Bits and Dust Management Core Bits Chisels Adaptors Step Drill Bits Twist Drill Bits Carbide Cutters Annular 22 2 2018 nbsp 0183 32 for instance 1 2 13 becomes 1 divided by 13 equals 0768 you subtract that from the major diameter 1 2 quot 500 which would give you 423 quot Pretty close to the standard 4219 or 27 64 quot In the 1 2 28 I get 036 so that gives me a minor dia of 464 quot Closest normally found drill I could find is a 11 8mm The charts below show you what size drill bit to use with a tap Tap sizes are shown as hole size – threads per inch Example 1 4 20 1 4″ hole 20 threads per inch Imperial 21 Piece Assorted x Set Titanium Twist Drill Bit Set Model 89383 Find My Store for pricing and availability 236 236 FlexTorq 26 Piece 1 4 in x Set Impact Driver Bit Set Model DWANGFT26SET