What Size Drill Bit To Use

Drill $.25 are the cutting tools of drilling machines. They can be made in whatsoever size to social club, but standards organizations have defined sets of sizes that are produced routinely by drill bit manufacturers and stocked by distributors.

In the U.S., fractional inch and judge drill bit sizes are in common employ. In about all other countries, metric drill bit sizes are most common, and all others are anachronisms or are reserved for dealing with designs from the US. The British Standards on replacing estimate size drill bits with metric sizes in the UK was first published in 1959.^{[ citation needed ]}

A comprehensive table for metric, fractional wire and tapping sizes can be found at the drill and tap size nautical chart.

Metric drill fleck sizes [edit]

Metric drill gear up, ane.0–6.0 mm by 0.1 mm, jobber length. The case that holds them in an indexed order (by size), via a graduated serial of holes, is called a drill index.

Metric drill chip sizes define the bore of the chip in terms of standard metric lengths. Standards organizations define sets of sizes that are conventionally manufactured and stocked. For instance, British Standard BS 328 defines 230 sizes from 0.two mm to 25.0 mm.

From 0.two through 0.98 mm, sizes are defined as follows, where North is an integer from two through nine:

• N · 0.1 mm
• N · 0.i + 0.02 mm
• Due north · 0.1 + 0.05 mm
• N · 0.1 + 0.08 mm

From 1.0 through two.95 mm, sizes are defined as follows, where Due north is an integer from x through 29:

• Due north · 0.1 mm
• North · 0.ane + 0.05 mm

From 3.0 through thirteen.9 mm, sizes are defined as follows, where N is an integer from xxx through 139:

• Northward · 0.i mm

From 14.0 through 25.0 mm, sizes are defined equally follows, where M is an integer from 14 through 25:

• One thousand · one mm
• M · 1 + 0.25 mm
• Thousand · 1 + 0.5 mm
• Grand · 1 + 0.75 mm

In smaller sizes, bits are available in smaller diameter increments. This reflects both the smaller drilled pigsty diameter tolerance possible on smaller holes and the wishes of designers to accept drill bit sizes available within at well-nigh 10% of an arbitrary hole size.

The price and availability of particular size bits does not alter uniformly beyond the size range. Bits at size increments of i mm are nigh commonly available, and lowest cost. Sets of bits in 1 mm increments might be found on a market stall. In 0.five mm increments, any hardware shop. In 0.1 mm increments, any engineers' store. Sets are non ordinarily bachelor in smaller size increments, except for drill bits below ane mm diameter. Drill bits of the less routinely used sizes, such as 2.55 mm, would accept to exist ordered from a specialist drill flake supplier. This subsetting of standard sizes is in contrast to general practice with number guess drill $.25, where information technology is rare to find a set on the market which does not incorporate every approximate.

In that location are too Renard series sequences of preferred metric drill bits:^[1]

• R5 (factor one.58) : M2.v, M4, M6, M10, M16, M24
• R10 (factor 1.26): M3, M5, M8, M12, M20, M30

Metric dimensioning is routinely used for drill bits of all types, although the details of BS 328 apply only to twist drill bits. For example, a set up of Forstner bits may contain ten, 15, xx, 25 and 30 mm diameter cutters.

Partial-inch drill bit sizes [edit]

Fractional-inch drill bit sizes are however in common use in the United States and in whatever factory (around the earth) that makes inch-sized products for the U.S. market.

ANSI B94.11M-1979 sets size standards for jobber-length directly-shank twist drill bits from 1/64 inch through ane inch in i/64 inch increments. For Morse taper-shank drill bits, the standard continues in ane/64 inch increments up to 1¾ inch, then 1/32 inch increments up to 2¼ inch, 1/16 inch increments up to 3 inches, 1/8 inch increments up to iii¼ inches, and a unmarried 1/4 inch increase to three½ inches. I aspect of this method of sizing is that the size increment between drill $.25 becomes larger as bit sizes get smaller: 100% for the footstep from 1/64 to 1/32, but a much smaller percentage between 1 47/64 and 1 iii/iv.

Drill bit sizes are written equally irreducible fractions. So, instead of 78/64 inch, or 1 14/64 inch, the size is noted every bit 1 vii/32 inch.

Below is a chart providing the decimal-fraction equivalents that are most relevant to partial-inch drill bit sizes (that is, 0 to 1 by 64ths). (Decimal places for .25, .5, and .75 are shown to thousandths [.250, .500, .750], which is how machinists usually think about them ["two-fifty", "five hundred", "seven-fifty"]. Machinists generally truncate the decimals subsequently thousandths; for example, a 27/64" drill scrap may be referred to in shop-floor speech equally a "four-20-i drill".)

Charts like this, printed at poster size, are widely posted on motorcar shop walls for handy reference by machinists equally they work. For some tasks it is faster and less abrasive to glance down a column of numbers on a poster than information technology is to punch calculator buttons or practise penciled arithmetics.

For anyone looking to create such a affiche or to tailor the design and colors to their own preferences, spreadsheet software makes this fast and easy to do. The tools that the software provides—formulas, cell formatting with rounding, autofill, and sorting past numerical society—obviate any manual calculation and data entry. For example, ane can create the inch nominal rows for the chart—with columns for inch fraction, inch decimal, and respective millimeter decimal conversion—using formulas, cell formatting with rounding, and autofill; and one can then create the metric nominal rows below that, with the inch decimal conversions existence provided by formula; and then one can sort the whole canvass by size lodge, automatically interposing the inch nominal and metric nominal rows past size gild. Font and colour can be chosen to make a poster-size chart that is easy to read from i or 2 meters away. Press can exist washed on a desktop printer, with the letter-size sheets then being stapled together to make upward the larger affiche.

Decimal-fraction equivalents [edit]

fraction in mm i⁄64 0.015625 0.396875 one⁄32 0.03125 0.79375 3⁄64 0.046875 1.190625 i⁄16 0.0625 ane.5875 5⁄64 0.078125 1.984375 3⁄32 0.09375 2.38125 7⁄64 0.109375 2.778125 1⁄8 0.125 3.175 9⁄64 0.140625 3.571875 five⁄32 0.15625 iii.96875 11⁄64 0.171875 4.365625 iii⁄sixteen 0.1875 four.7625 13⁄64 0.203125 5.159375 7⁄32 0.21875 5.55625 15⁄64 0.234375 5.953125 one⁄4 0.250 6.350

fraction in mm 17⁄64 0.265625 6.746875 9⁄32 0.28125 7.14375 19⁄64 0.296875 7.540625 5⁄16 0.3125 7.9375 21⁄64 0.328125 8.334375 11⁄32 0.34375 8.73125 23⁄64 0.359375 nine.128125 3⁄eight 0.375 9.525 25⁄64 0.390625 9.921875 13⁄32 0.40625 10.31875 27⁄64 0.421875 10.715625 vii⁄16 0.4375 11.1125 29⁄64 0.453125 11.509375 15⁄32 0.46875 eleven.90625 31⁄64 0.484375 12.303125 1⁄two 0.500 12.700

fraction in mm 33⁄64 0.515625 xiii.096875 17⁄32 0.53125 13.49375 35⁄64 0.546875 13.890625 ix⁄16 0.5625 14.2875 37⁄64 0.578125 fourteen.684375 nineteen⁄32 0.59375 xv.08125 39⁄64 0.609375 xv.478125 5⁄eight 0.625 15.875 41⁄64 0.640625 16.271875 21⁄32 0.65625 16.66875 43⁄64 0.671875 17.065625 eleven⁄xvi 0.6875 17.4625 45⁄64 0.703125 17.859375 23⁄32 0.71875 18.25625 47⁄64 0.734375 xviii.653125 three⁄4 0.750 nineteen.050

fraction in mm 49⁄64 0.765625 xix.446875 25⁄32 0.78125 19.84375 51⁄64 0.796875 xx.240625 13⁄xvi 0.8125 20.6375 53⁄64 0.828125 21.034375 27⁄32 0.84375 21.43125 55⁄64 0.859375 21.828125 7⁄8 0.875 22.225 57⁄64 0.890625 22.621875 29⁄32 0.90625 23.01875 59⁄64 0.921875 23.415625 15⁄16 0.9375 23.8125 61⁄64 0.953125 24.209375 31⁄32 0.96875 24.60625 63⁄64 0.984375 25.003125 one 1.000 25.400

Number and letter gauge drill bit sizes [edit]

Number drill flake gauge sizes range from size fourscore (the smallest) to size 1 (the largest) followed by letter estimate size A (the smallest) to size Z (the largest). Although the ASME B94.11M twist drill standard, for example, lists sizes every bit pocket-sized every bit size 97, sizes smaller than 80 are rarely encountered in exercise.

Number and letter sizes are commonly used for twist drill $.25 rather than other drill forms, every bit the range encompasses the sizes for which twist drill $.25 are most ofttimes used.

The gauge-to-diameter ratio is not defined by a formula; it is based on—but is not identical to—the Stubs Steel Wire Estimate, which originated in United kingdom during the 19th century.^[two] The accompanying graph illustrates the change in diameter with modify in gauge, every bit well equally the reduction in footstep size equally the approximate size decreases. Each pace along the horizontal axis is one gauge size.

Number and letter gauge drill $.25 are all the same in common employ in the U.S. and to a lesser extent the U.k., where they take largely been supplanted by metric sizes. Other countries that formerly used the number serial have for the most part also abased these in favour of metric sizes.^{[ citation needed ]}

Drill bit conversion table [edit]

click to encounter a ruler comparing millimeters to fractions of an inch

gauge in mm 104 0.0031 0.079 103 0.0035 0.089 102 0.0039 0.099 101 0.0043 0.109 100 0.0047 0.119 99 0.0051 0.130 98 0.0055 0.140 97 0.0059 0.150 96 0.0063 0.160 95 0.0067 0.170 94 0.0071 0.180 93 0.0075 0.191 92 0.0079 0.201 91 0.0083 0.211 ninety 0.0087 0.221 89 0.0091 0.231 88 0.0095 0.241 87 0.010 0.254 86 0.0105 0.267 85 0.011 0.279 84 0.0115 0.292 83 0.012 0.305 82 0.0125 0.318 81 0.013 0.330 80 0.0135 0.343 79 0.0145 0.368

gauge in mm 78 0.016 0.406 77 0.018 0.457 76 0.020 0.508 75 0.021 0.533 74 0.0225 0.572 73 0.024 0.610 72 0.025 0.635 71 0.026 0.660 70 0.028 0.711 69 0.0292 0.742 68 0.031 0.787 67 0.032 0.813 66 0.033 0.838 65 0.035 0.889 64 0.036 0.914 63 0.037 0.940 62 0.038 0.965 61 0.039 0.991 60 0.040 1.016 59 0.041 1.041 58 0.042 1.067 57 0.043 1.092 56 0.0465 i.181 55 0.052 1.321 54 0.055 ane.397 53 0.0595 1.511

estimate in mm 52 0.0635 1.613 51 0.067 1.702 fifty 0.070 i.778 49 0.073 ane.854 48 0.076 i.930 47 0.0785 1.994 46 0.081 2.057 45 0.082 2.083 44 0.086 ii.184 43 0.089 ii.261 42 0.0935 ii.375 41 0.096 ii.438 40 0.098 2.489 39 0.0995 2.527 38 0.1015 2.578 37 0.104 2.642 36 0.1065 2.705 35 0.110 2.794 34 0.111 2.819 33 0.113 2.870 32 0.116 2.946 31 0.120 iii.048 30 0.1285 3.264 29 0.136 3.454 28 0.1405 3.569 27 0.144 3.658

approximate in mm 26 0.147 3.734 25 0.1495 3.797 24 0.152 3.861 23 0.154 three.912 22 0.157 iii.988 21 0.159 iv.039 20 0.161 4.089 19 0.166 four.216 xviii 0.1695 4.305 17 0.173 4.394 16 0.177 four.496 xv 0.180 4.572 14 0.182 4.623 13 0.185 iv.699 12 0.189 4.801 eleven 0.191 4.851 10 0.1935 four.915 nine 0.196 four.978 8 0.199 5.055 7 0.201 5.105 half-dozen 0.204 five.182 5 0.2055 5.220 4 0.209 v.309 iii 0.213 five.410 2 0.221 5.613 1 0.228 5.791

judge in mm A 0.234 five.944 B 0.238 6.045 C 0.242 vi.147 D 0.246 vi.248 Due east 0.250 6.350 F 0.257 6.528 G 0.261 vi.629 H 0.266 6.756 I 0.272 6.909 J 0.277 vii.036 K 0.281 7.137 L 0.290 seven.366 M 0.295 7.493 N 0.302 seven.671 O 0.316 viii.026 P 0.323 8.204 Q 0.332 eight.433 R 0.339 8.611 Southward 0.348 eight.839 T 0.358 nine.093 U 0.368 ix.347 Five 0.377 9.576 West 0.386 9.804 Ten 0.397 10.08 Y 0.404 x.26 Z 0.413 ten.49

Screw-machine-length drill [edit]

The shortest standard-length drills (that is, lowest length-to-diameter ratio) are screw-machine-length drills (sometimes abbreviated South/M). They are named for their apply in screw machines. Their shorter flute length and shorter overall length compared to a standard jobber scrap results in a more rigid drill bit, reducing deflection and breakage. They are rarely bachelor in retail hardware stores or dwelling house centers.

Jobber-length drill [edit]

Jobber-length drills are the most commonly found type of drill. The length of the flutes is between 9 and 14 times the diameter of the drill, depending on the drill size. Then a 1 / 2  in (12.7 mm) diameter drill volition exist able to drill a hole 4+ ane / two  in (114.3 mm) deep, since it is 9 times the diameter in length. A ane / eight  in (3.175 mm) diameter drill tin drill a hole 1+ five / 8  in (41.275 mm) deep, since it is thirteen times the diameter in flute length.^[3]

The term jobber refers to a wholesale distributor—a person or visitor that buys from manufacturers and sells to retailers.^{[ citation needed ]} Manufacturers producing drill bits "for the trade" (as opposed to for specialized machining applications with item length and design requirements) made ones of medium length suitable for a wide variety of jobs, because that was the type almost desirable for full general distribution. Thus, at the fourth dimension that the name of jobber-length drill $.25 became mutual, information technology reflected the same concept that names like general-purpose and multipurpose reverberate.^{[ citation needed ]}

Aircraft-length drill [edit]

Extended-reach or long-series drills are commonly chosen aircraft-length from their original use in manufacturing riveted aluminum shipping. For bits thicker than a minimum size such as 1⁄8 -inch (3.175 mm), they are available in fixed lengths such as vi, 8, 12 or 18 inches (152, 203, 305 or 457 mm) rather than the progressive lengths of jobber drills.

11/32 inch drills: long-series Morse, plain Morse, jobber

The epitome shows a long-series drill compared to its diametric equivalents, all are eleven⁄32 inch (8.7313 mm) in diameter. The equivalent Morse taper drill shown in the centre is of the usual length for a taper-shank drill. The lower drill fleck is the jobber or parallel shank equivalent.

Eye drill bit sizes [edit]

Middle drills, numbers 1 (bottom) through to 6 (top)

Center drills are available with two different included angles; 60 degrees is the standard for drilling centre holes (for instance for subsequent eye support in the lathe), but 90 degrees is also common and used when locating holes prior to drilling with twist drills. Center drills are made specifically for drilling lathe centers, just are oftentimes used every bit spotting drills because of their radial stiffness.

Size designation Drill bore [inches (mm)] 5/0 0.010 in (0.254 mm) four/0 0.015 in (0.381 mm) iii/0 0.020 in (0.508 mm) 2/0 0.025 in (0.635 mm) 0 1⁄32  in (0.794 mm) 1 3⁄64  in (i.191 mm) 2 five⁄64  in (one.984 mm) 3 7⁄64  in (2.778 mm) 4 1⁄eight  in (3.175 mm) four½ ix⁄64  in (iii.572 mm) 5 3⁄sixteen  in (four.763 mm) 6 7⁄32  in (5.556 mm) 7 one⁄four  in (6.350 mm) eight 5⁄16  in (7.938 mm)

Estimate Body bore [inches (mm)] BS1 1⁄viii  in (3.175 mm) BS2 three⁄sixteen  in (4.763 mm) BS3 1⁄4  in (half dozen.350 mm) BS4 5⁄16  in (seven.938 mm) BS5 7⁄xvi  in (eleven.113 mm) BS5A ane⁄2  in (12.700 mm) BS6 5⁄8  in (15.875 mm) BS7 3⁄iv  in (19.050 mm)

Spotting drill bit sizes [edit]

Spotting drills are available in a relatively small-scale range of sizes, both metric and imperial, as their purpose is to provide a precise spot for guiding a standard twist drill. Commonly bachelor sizes are 1/viii", 1/iv", 3/eight", ane/two", 5/8", 3/four", iv mm, 6 mm, eight mm, 10 mm, 12 mm, 14 mm, 16 mm and 18 mm. The drills are well-nigh unremarkably available with either 90° or 120° included angle points.

See likewise [edit]

• Drill and tap size chart

References [edit]

1. ^ Dasarathi-Cadem (2 February 2017). "Preferred sizes in technology". CNC etc . Retrieved 6 September 2017.
2. ^ Pöll, J. South. (June 1999). "The story of the guess". Anaesthesia. 54 (6): 575–581. doi:10.1046/j.1365-2044.1999.00895.x. ISSN 0003-2409. PMID 10403873. S2CID 41519791.
3. ^ "Jobber Length Twist Drill Sizes".

What Size Drill Bit To Use,

Source: https://en.wikipedia.org/wiki/Drill_bit_sizes

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