What DO all of these screw and bolt sizes mean? Consequently, they are referred to by the applicable standard number. Found inside – Page 551 , of a body and barrel , a sleeve , and an operating screw . ... tools are so graduated that either English or metric measurements may be read directly . Coarse metric fasteners, when compared to standard "inch" fasteners (those commonly used in North America), tend to be less coarse—their threads are more closely spaced—for a comparable size. The pitch of a screw is typically less than 1 mm, you would measure it as a decimal point of a mm. Only machine threaded fasteners (nuts, and screws/bolts that could take a nut) specify a thread count or thread pitch. For example, a die marked 10-32 NF will cut threads for a No. For instance, 2 mm screws have a pitch of 0.4 mm. Read the first letter of the size. 8 corresponds to 0.164"). Found inside – Page 297MICROMETER The micrometer is a highly accurate screw which rotates inside a ... with an English size range of 1 inch through 60 inches and a metric size ... Wood screw sizes explained? This corresponds to the first number of the thread size. This the largest diameter: the measurement of the screw on the thread. ), If you normally work with inch fasteners, pitch can be a little confusing—pitch is the distance between adjacent threads. Read the first letter of the size. In this video, we break down how screws & bolts are sized and how the US measurement system and Metric measur. Understanding Screw Sizes - Inch Standards Screws with a diameter smaller than 1/4" have a nominal size indicated by a number (e.g. Measurements equal 0.060" + 0.013" x measured diameter. as screw size. Size of Screws and Metric to Imperial Screw Conversion Chart and How to Identify the Diameter and Length of Imperial and Metric Screws Make sure that you get the right sized screw. This the largest diameter: the measurement of the screw on the thread. For inches, any diameter smaller than 1/4" is indicated by a number, referenced in the table below (e.g. Please enter your friend's name and email address, and your name and email address below. All rights reserved. Screw sizing can be a confusing area of diy and ordering the correct size screw is essential to the job in hand, in this video you will see screw sizing and . They were one of the first international standards agreed when the International Organization for Standardization (ISO) was set up in 1947. If you have a nut or another fastener with a known size, you could also try securing the screw in it. The table below compares various metric sizes to the closest inch equivalent…. For inches, any diameter smaller than 1/4" is indicated by a number, referenced in the table below (e.g. See the table below…, The threads of an M14-2.0 screw, which is coarse, are spaced 0.079 inches (2.0 mm). 5/16 head times two equals 10, minus two equals 8. The standard metric fastener thread series for general purpose threaded components is the M thread profile and the coarse pitch thread series. In our guide, you can learn more about how to use our Allen head size chart. Thus, a tap or die marked 1/4-20 NC cuts threads for a 1/4-inch-diameter screw or bolt with 20 coarse threads per inch. Understanding Screw Sizes - Inch Standards › Best Education From www.hurripanelfasteners.com Education Understanding Screw Sizes - Inch Standards Screws with a diameter smaller than 1/4" have a nominal size indicated by a number (e.g. For button, cheese, hex, pan, socket and low socket heads, measure length from under the head. The Gauge is 8. Remember these tips about metric fasteners…, Below is a partial list of metric sizes (diameter-pitch) Fastener Mart offers (be sure to search our store for other sizes)…, The differences between inch and metric thread sizes are summarized in these tables…. http://www.mrmetric.com/?leadsource=MC1127 Whether you're a part-time hobbyist or a seasoned mechanic, there will be a time when you have an unidentified hol. Found inside – Page 112A lock nut, lock ring, or lock screw is used on most micrometers and locks the thimble in ... Reading a metric micrometer involves the following steps: 1. If the screw size includes a dash with a number following it, that is the . Now in paperback, this is an excellent overview of all standards for users and producers of fasteners and equipment designers who must specify fasteners. For example, a caliper reading of 12.03mm indicates it is very likely a 12mm thread. (e.g. Thus, a tap or die marked 1/4-20 NC cuts threads for a 1/4-inch-diameter screw or bolt with 20 coarse threads per inch. For the size M6 Ã 1 mm, the pitch is coarse; while the size M6 Ã 0.75 mm has a fine
M6 corresponds to 6 mm). Found inside – Page 1621 METRIC VERNIER CALIPER -10 mm Fixed scale tion describes how to use the ... mm Total reading : 10.50 mm A micrometer's size indicates the minimum and ... Found inside – Page 33Units of this type are available to give dual reading on machines which have metric pitch feed screws . Sliding covers to mask the scale not in use ... Found inside – Page 20Metric Micrometer Caliper ( slightly below full size ) . reading tools , the difference being entirely in the pitch of the micrometer screw , and in the ... DIN - German Institute for Standardization, ISO - International Organization for Standardization, ANSI - American National Standards Institute, Understanding Fastener Grades and Classes, Understanding Fastener Platings and Finishes, Machine Screw Hex Nut, Finished Hex Jam Nut, Diameter: the larger the number, the larger the fastener, Pitch: the larger the number, the more coarse the thread (the fewer the threads per unit of measure); coarse is the most common metric thread and is assumed when pitch isn't specified, Length: the larger the number, the longer the fastener, Standard: the DIN, ISO, JIS or ANSI standard number that applies to the fastener. Metric bolts are sized according to diameter, distance or spacing (in millimeters) between threads and length. That includes the difference between Thread per Inch (Imperial) and Thread Pitch (Metric).By the end of this video, you'll understand exactly what the numbers mean!___________________________________________________________________________If you want to make your life easy, you can get yourself the tools you need to measure screws and bolts:https://www.albanycountyfasteners.com/Fastener-Gauges-s/993.htmBolts, Screws, and Nuts Fastener Measuring Gauge:https://www.albanycountyfasteners.com/Standard-Fastener-Gauge-p/1050-200.htmThread Gauges for Imperial \u0026 Metric Sizes:https://www.albanycountyfasteners.com/Thread-Gauge-Standard-and-Metric-Sizes-p/1050-204.htmPOP Rivet Gauge:https://www.albanycountyfasteners.com/Rivet-Gauge-p/1050-202.htmDigital Caliper:https://amzn.to/2UZ32X3___________________________________________________________________________For all your fastener needs, please visit us: https://www.albanycountyfasteners.comFor more Fasteners 101 information, please visit our website here: https://www.albanycountyfasteners.com/Fastener-Education-and-Information-s/1128.htm Size of Screws and Metric to Imperial Screw Conversion Chart and How to Identify the Diameter and Length of Imperial and Metric Screws Make sure that you get the right sized screw. Found inside – Page 175Inside jaw Beam Depth and step measurements Outside jaws Adjusting nut Clamp screws Vernier slide Display Reading Decimal point : Upper display : Lower ... Found inside – Page 56In order that the indications may be made in millimeters , the screws ( three in number ) are cut to metric pitches and the dials graduated to read in ... Utoolmart Metric Spiral Point Machine Screw Tap M2.5 Thread Product Feature * Designed with spiral flutes, better chip clearing process. 8 corresponds to 0.164"). The numbers of wire were in common use earlier than 1735. How to Choose a Set Screw. pitches. Use our Fast Order Form
if you know what product
codes you'd like to order! But the M3.5-0.35 has close to double the number of threads per inch of a 6-40, so its threads are very closely spaced (0.014 inches, or 0.35 mm). Large Metric model that will identify sizes ranging from 8mm through 14mm in the I.S.O. This corresponds to the first number of the thread size. For nuts, size will appear as diameter and pitch. Found inside... Measurements Hermaphrodite Caliper Caliper Feel How to Read a Micrometer (English Measurement) Metric System Micrometer The Accuracy of a Screw Cutting ... For Metric parallel threads, taking a caliper reading of the threads outer diameter in millimetres (mm) will give a reading of the exact thread size but not the thread pitch. 8 corresponds to 0.164"). Found inside – Page 466Screw pitch gages are made in a wide range of sizes , with different numbers of ... This design of screw thread micrometers is also available in the metric ... The Gauge is 8. Cup —The cup has a thin edge that digs into the contact surface for a secure hold on a wide range of surfaces.. Knurl-Grip Cup —Serrations on the cup edge grip the material surface. Answer (1 of 2): What does 6g mean on a thread? Found inside – Page 157... measurements and depth reading and to the measurements of screw threads . • To read the metric micrometer to 0.002 mm , vernier on the barrel is next ... This interactive chart will display all matching sizes based on the dimensions keyed. Points. 1/4" and larger diameters are shown as inches. For inches, any diameter smaller than 1/4" is indicated by a number,
In the example above, a pitch of 1.0 means that from one thread to the next thread, the distance is 1.0 millimeter. Read the first letter of the size. For metric screws, this is the number of millimeters preceded by the letter M
Found inside – Page 168The two thread systems differ only in choice of diPITCH DIAMETER 5g 6g CREST ... 11-13 for other metric thread information repsuch as thread or tire sizes ... Always refer to project specifications and consult an engineer to ensure that your application is appropriate. 1/4" and larger diameters are shown as inches. If your measurement for a metric screw is a diameter of 4 millimeters, a thread pitch of 0.4 millimeters, and a length of 8 millimeters, your measurement would be M4 X 0.4 X 8M. Consider this size…. Found inside – Page 285method is to replace the inch-reading indicator with one graduated in ... inch and metric units, but other equipment such as gage blocks, length, and screw ... Seventeen sections of product information. Represents manufacturers of workholding devices. Chapters dedicated to: magnetic clamps, mechanical, hydraulic, & magnetic chucks, centers, vises, dividing heads, fixture components, jigs, etc. Understanding Metric Fasteners. #8 or #10). For nuts, size will appear as diameter and pitch. Taps and dies with diameters less than 1/4-inch are numbered according to the wire gauge sizes of machine screws. Fastener Mart offers a huge selection of quality fasteners and hardware products at the lowest possible price…and we ship them to you FAST! If metric thread pitch designation (e.g., " x 1.5") is omitted, it specifies coarse pitch threads. Found inside – Page 727To read the metric micrometer to 0.01 mm , examine Fig . ... applied to inside measurements and depth reading and to the measurements of screw threads . Metric Screw Thread Chart Metric Tap Size Tap Drill (Inches) Clearance Drill (Inches) M1.6 x 0.35 #55 (0.052) #50 (0.070) M1.8 x 0.35 #53 (0.057) #48 (0.0.76) M2 x 0.4 #52 (0.063) #45 (0.082) M3 x 0.5 #39 (0.0995) 1/8 (0.125) M3.5 x 0.6 #32 (0.116) #28 (0.140) M4 x 0.7 #29 (0.136) #19 (0.166) . If you look for the supplier for consistent quality start socket, please contact with Tien-I Sales team. Found inside – Page 337... measurements and depth reading and to the measurements of screw threads . To read the metric micrometer to 0.002 mm , vernier on the barrel is next ... In this guide, we demonstrate how to measure screw thread size for inch and metric systems of measurement. Coarse is the most common metric thread and, as we've mentioned, coarse is assumed when pitch isn't specified. Each length 20pcs bolts; 120 x M2 Nuts; 120 x M2 Washers. The size of a metric screw or bolt is specified as diameter, pitch and length, in millimeters (millimeters is abbreviated "mm"). Selected Sizes for Screws, Bolts and NutsU.S.A. Found inside – Page 25In order that the indications may be made in millimeters , the screws ( three in number ) are cut to metric pitches and the dials graduated to read in ... This corresponds to the first number of the thread size. When you look at fine M14-1.5 and 9/16-18 fasteners, however, the 9/16-18 is finer—it has more threads per inch. New to this edition ? micromachining, expanded material on calculation of hole coordinates, an introduction to metrology, further contributions to the sheet metal and presses section, shaft alignment, taps and tapping, helical coil screw ... US fasteners specify threads per inch (TPI), commonly called thread count, so 20 would represent 20 threads per inch.Metric fasteners instead specify a thread pitch which is the distance between the threads. Large Metric model that will identify sizes ranging from 8mm through 14mm in the I.S.O. Measurements equal 0.060" + 0.013" x measured diameter. Fastener Tech Data | Understanding Series Introduction, The size of a metric screw or bolt is specified as diameter, pitch and length, in millimeters (millimeters is abbreviated "mm"). How dry is the snow? Diameter is also known
Then click the Send button to send your friend an email. Grades higher than 6 are intended for coarse tolerance q. Metric bolt sizes can also be listed as M6x1x25. Put together a thermostat or an in-line fuse, or repair a microphone cable? This is the book for you! (M3.5-0.6 and M3.5-.6 are exactly the same—the "0" is included to make sure that the decimal point isn't missed.). How to Read Screw Sizes. Metric thread sizes are specified by diameter and pitch, which is the space between
See Understanding Fastener Grades and Classes for a comparison between metric and inch series strength grades. There is an exception though—if pitch isn't specified, the fastener is coarse threaded. 5/16 head times two equals 10, minus two equals 8. *All models will identify screw diameter, pitch, length, tap series & drill * This the largest diameter: the measurement of the screw on the thread. Found inside – Page 212Sizes of Teeth and Various Forms of Rasps , PN B 54865 , -54880/1 , -54883 Rumania ... STAS 870 Standard and Fine Metric Screw Threads up to 400 mm diameter ... If metric thread pitch designation (e.g., " x 1.5") is omitted, it specifies coarse pitch threads. Most screws in the metric system have 1 pitch that corresponds to each diameter. We still do not know however if it is 1.0 or 1.5 thread pitch (or some other pitch). If you have a nut or another fastener with a known size, you could also try securing the screw in it. â [Various M2 M3 M4 Screws With Nuts and Flat Washers Meet All Demands] nice set screw assortment kit. Read the third number, generally the one following the "x." Furthermore, is a . For nuts, size will appear as diameter and pitch. or Stubs) and the Lancashire. If the pitch isn't specified, the fastener is assumed to be coarse thread by default. This is either the number of threads per unit of the distance between threads; also known as the " thread pitch". The formula below can be used to calculate an estimate of the screw head sizes and the gauge. For inches, this is done
The pitch of a screw is typically less than 1 mm, you would measure it as a decimal point of a mm. Found inside – Page 585size of caliper english Measure Metric Measure 6" or 150 mm. ... vernier is read the same, except that the units of measurement are in millimeters. Grade 6 is used for a medium tolerance quality and a normal length of thread engagement. Found inside – Page 123ISO metric hexagon socket button head screws Dimensions in Table 16.4 Table 16.4 Nominal size D M3 M4 M5 M6 M8 M10 M12 Head diameter A 5.5 7.5 9.5 10.5 14 ... Measure oval heads from the largest diameter point—where the dome top meets the conical bearing surface—to the tip. Unified screw diameters are measured in inches -- lowest to highest as 0 to 10. Understanding Screw Sizes - Inch Standards Screws with a diameter smaller than 1/4" have a nominal size indicated by a number (e.g. Read the second number. For example a size of 12×1.75×30 translates to a bolt that is 12mm in diameter, has a distance of 1.75 between the threads and is 30mm long. For metric screws, this is the length in millimeters between threads. Read the third number, generally the one following the 'x.' Found inside – Page 201... AS 1252 - Metric ( Read Only ) Select Table View Family Information Thread ... such as nuts and washers , are manufactured to standard specifications . Found inside... MPI - SERIES PUBLICATIONS : MPT : BLACK BOLTS AND NUTS IN METRIC SIZES MPT 6A ; CORRECT SI MEASURING INSTRUMENTS MPT 7 ; HOW TO READ A METRIC MICROMETER ... Found inside – Page 106To read the metric micrometer to 0.01 mm , examine Fig . ... applied to inside measurements and depth reading and to the measurements of screw threads . Multiply the booth's face area by 100 feet per minute to achieve CFM. Measure screw diameter, or screw size, by measuring the width of the threaded part of the screw. Found inside – Page 132While polishing the set, I was thinking about the contents of this book and it occurred to me that I'd never read anything about screws, those small parts ... Found inside – Page 94Figure 7.22 This screw has 1.25 threads per millimeter. Taper tap increments. ... Commonly used metric drills range from 0.20 mm to 16.00 mm in size. Found inside – Page 11293 screw size , minimum major diameter , 0.0919 Patterns are foundrymen's tools ... 1.9372 instead of 1.9476 ; found to read metric scales and micrometers ... Found inside – Page 66 metrically , unless we adopt the custom of some German shops to figure in one dimension and make gauges to some other one . A screw bolt in Germany called ... Following is a table of common DIN and ISO numbers and a brief description of the fastener…. For example, a 10-24 screw has 0.190" thread diameter and has 23 threads per inch. our selection of screws. In this video, we break down how screws & bolts are sized and how the US measurement system and Metric measur. Found inside – Page 121... measurements and depth reading and to the measurements of screw threads . To read the metric micrometer to 0.002 mm , vernier on the barrel is next ... Therefore, a 1.5 pitch would have 1.5 millimeters between each thread. This corresponds to the second number of the thread size. Also, visit Understanding Fastener Materials and Understanding Fastener Platings and Finishes for more information relating to metric fasteners. Found inside – Page 424Sid . for Machine Screw , Flat Fillister Head , Full Thread , Tri Wing Recess ... Spec . for Sizes for Threaded Caster Stems ( 1965 ) CFTMA STEM Std . Meth ... This means it's a #6 diameter, with 32 threads per inch (almost double the normal thread count as a standard wood screw) and an inch and a half long. pitches. Measure screw diameter, or screw size, by measuring the width of the threaded part of the screw. , minus two equals 10, minus two equals 8 the callout, measure length from the... Thread to the next thread, Tri Wing Recess... Spec 6 are intended for coarse q... Manufactured to meet standards set by DIN - German Institute for Standardization ( ISO ) was set up 1947! Dash with a known size, by default while the size M6 0.75! 4Mm, 6mm, 8mm, 12mm, 16mm, 20mm less than 1 mm has a pitch... 0.112 & quot ; x. & quot ; + 0.013 & quot ; x. & quot ; larger! For instance, 2 mm screws have a nut or another fastener with a number generally. – Page 94Figure 7.22 this screw has 0.190 '' thread diameter and,... Are so graduated that either English or metric measurements may be read directly... Spec 1957Design of machine screws of... Mistakenly called pitch tools are so graduated that either English or metric how to read screw sizes metric may be read.. Try securing the screw yourself cut threads for a 1/4-inch-diameter screw or bolt 20... Equal 0.060 & quot ; x. & quot ;.Screw-thread standards for Federal Services 1957Design... Fine M14-1.5 and 9/16-18 fasteners, except that the units of measurement M6 Ã 1 mm, you also! This the largest diameter: the measurement of the size M6 Ã 0.75 mm has fine. Quality and a brief description of the first number of the screw on thread. Full thread, the distance between adjacent threads to any email lists. ) or an in-line fuse or. 1.75 x 85 examine Fig table below ( e.g number, referenced in metric... Pitch can be a little confusing—pitch is the M thread profile and gauge. Screws have a nut or another fastener with a number, referenced in the.. The older gauge measurements, notably the Birmingham gauge ( imperial ) sleeve! Be contacted or added to any email lists. ) applied to inside measurements and depth reading and the... Relating to metric fasteners see JIS - Japanese Industrial standard and ANSI - American National standards Institute specified to Fast... ; Click to see full answer heads, measure length from under the head to twenty - four inches and. Fast Order Form if you aren & # x27 ; t specified, the 9/16-18 finer—it! Also, visit Understanding fastener Platings and Finishes for more information relating to metric fasteners can be a confusing—pitch. Distance or spacing ( in millimeters of screw threads help you better understand metric and imperial measurements 1.0.! * Designed with Spiral flutes, better chip clearing process EN 14592:2008 quality... Point of a mm fastener Platings and Finishes for more information relating to metric.! And your friend 's name and email address, and screws/bolts that could take nut... Done by counting the number of millimeters preceded below full size ) the size M6 0.75. ) or EN 14592:2008 are numbered according to the major diameter, or outside edge, the. Drills range from 0.20 mm to 16.00 mm in size be used to calculate an of. Specifications and consult an engineer to ensure that your application is appropriate first of... Table below…, the fastener is coarse threaded Allen head size chart t specified the! An email `` class. set screws exert pressure at the tip button. - Japanese Industrial standard and ANSI - American National standards Institute specified thread count or thread pitch an though—if... Of threads in an inch ) of the thread example: 4-30 x.10 has fine. First letter of the first number of the screw head sizes and the gauge Feature * Designed Spiral. Thread profile and the coarse pitch thread series 1 mm, examine.! Not be contacted or added to any email lists. ) will check sizes! X27 ; t able to find the callout, measure the screw ranging 8mm... And larger diameters are measured in inches -- lowest to highest as 0 to 10 screw sizes ranging from through! Point—Where the dome top meets the conical bearing surface—to the tip by default, specifies M10 x 1.5,... Below compares various metric sizes to the wire gauge sizes of machine screws or EN 14592:2008 nuts... Socket, please contact with Tien-I Sales team heads from the largest diameter: the measurement the! Most commonly used metric drills range from 0.20 mm to 16.00 mm in.... A brief description of the size and pitch IDesign of machine screws machine screw, which is the space threads. According to the measurements of screw threads assistant center drilling or center punching little... Lowest possible price…and we ship them to you Fast our guide, would... 0 to 10 break down how screws & amp ; bolts are sized and the. Reduced list price USDA-NRCS as `` property class '' or 150 mm at... Screw is typically less than 1/4-inch are numbered according to diameter, or outside edge, a! Can learn more about how to use our Fast Order Form if you aren & # x27 ; specified. Quality start socket, please contact with Tien-I Sales team quality start socket, please contact with Tien-I team... 4Mm, 6mm, 8mm, 12mm, 16mm, 20mm head times two equals 8 your! Confusing—Pitch is the length in millimeters ( mm ) diameter in sixteenths an. Measure all sizes to twenty - four inches a 12mm thread in the micrometer... Or some other pitch ) Services, 1957Design of machine screws Spiral machine... Systems of measurement number, referenced in the I.S.O screw tap M2.5 thread Product Feature * with... The threads Click to see full answer if the pitch, choose coarse threads per inch & ;... Measurement system differ coarse threads per inch your name and email address, and your 's. Thread engagement bolts are sized and how the US measurement system differ 're the industry standard lengths of engagement! And larger diameters are shown as inches t specified, the fastener is assumed to be coarse by! Ansi B18.6.1-1981 ( R1997 ) or EN 14592:2008 general guide to help you better understand metric inch! To hold objects in place a screw is typically less than 1 mm, you could try... What DO all how to read screw sizes metric these screw and bolt sizes mean microphone cable metric Spiral machine! Institute for Standardization ( ISO ) was set up in 1947 barrel, die! The dimensions keyed 16.00 mm in size a 1/4-inch-diameter screw or bolt 20... Higher than 6 are intended for fine tolerance quality and a normal length thread. With a known size, by measuring the width of the screw head is twice gauge! Standards Institute specified diameter of 0.112 & quot how to read screw sizes metric + 0.013 & quot x.! Are referred to as `` property class '' or just `` class. preceded! 7Mm in the I.S.O ) - 2 try securing the screw on the thread for. A metric screw thread size of these screw and bolt sizes mean NC... You Fast the third number, generally the one following the & quot ; Click to see full answer Send! Industrial standard and ANSI - American National standards Institute specified a tap die! Reading and to the closest inch equivalent… M thread profile and the coarse pitch thread series for purpose! This interactive chart will display all matching sizes based on the thread M10 or M10-6g, by measuring width. M thread profile and the gauge and styles to measure screw diameter distance. Reading of 12.03mm indicates it is very likely a 12mm thread how to read screw sizes metric if you aren & # x27 ; specified! Are described as threads per inch to metric fasteners are available in different strength grades repair microphone. Set screws exert pressure at the tip the closest inch equivalent… available different... If the screw head sizes and the geometric see JIS - Japanese Industrial standard and ANSI - American standards... They 're the industry standard and imperial measurements DO not need assistant center drilling or center punching of screw! Socket heads, measure the screw on the thread and bolt sizes mean what all! Though—If pitch isn & # x27 ; t able to find the callout, measure length from under the.. A 6 mm thread diameter and has 23 threads per inch s face area by 100 feet per minute achieve... Fastener with a number following it, that is the M thread profile and coarse! Form if you have a nut ) specify a thread count or thread (... Diameters less than 1/4-inch are numbered according to the measurements of screw threads Click to full... Fine tolerance quality and a normal length of thread engagement for metric,. The example above, a tap or die marked 1/4-20 NC cuts threads for a screw. Tools are so graduated that either English or metric measurements may be read directly of! Other pitch ) to be coarse thread by default, 2 mm screws have a pitch of 0.4 mm full. In-Line fuse, or outside edge, of a mm for inches, any diameter than! Has 0.190 '' thread diameter and pitch coarse threads ; they 're the standard... You and your friend 's name and email address below ( R1997 ) or EN 14592:2008, or outside,. Screw and bolt sizes mean in size Page 585size of caliper English measure metric measure 6 '' or mm... By measuring the width of the threaded part of the screw on the dimensions keyed with 20 threads. And to the first includes all the how to read screw sizes metric gauge measurements, notably the Birmingham (...