{"id":306,"date":"2024-09-17T17:59:27","date_gmt":"2024-09-17T17:59:27","guid":{"rendered":"https:\/\/leech.caltech.edu\/wp\/?page_id=306"},"modified":"2024-09-19T20:19:45","modified_gmt":"2024-09-19T20:19:45","slug":"us-imperial-screw-sizes","status":"publish","type":"page","link":"https:\/\/leech.caltech.edu\/cntl\/?page_id=306","title":{"rendered":"\u201cImperial\u201d screw sizes"},"content":{"rendered":"\n<div class=\"wp-block-group cntl-top-line has-global-padding is-layout-constrained wp-container-core-group-is-layout-2 wp-block-group-is-layout-constrained\" style=\"padding-right:0;padding-left:0\">\n<div class=\"wp-block-group has-border-color has-global-padding is-layout-constrained wp-block-group-is-layout-constrained\" style=\"border-color:#3f83b4;border-radius:4px\"><\/div>\n<\/div>\n\n\n\n<p>Imperial screws are designated by their diameter (in inches) and pitch (revolutions per inch). For instance, \u00bc-20 means: diameter 0.25\u201d, 20 threads per inch. Smaller screws are designated by a numerical gauge, larger numbers correspond to larger screws.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">On this page:<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"#drills\" data-type=\"internal\" data-id=\"#drills\">Drills to use for making screw holes<\/a><\/li>\n\n\n\n<li><a href=\"#diameters\">Actual diameters of imperial screws<\/a><\/li>\n\n\n\n<li><a href=\"#heads\">Dimensions of the heads of imperial screws<\/a><\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"drills\">Drills for screw holes<\/h2>\n\n\n\n<figure class=\"wp-block-table is-style-stripes\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Screw size<\/th><th class=\"has-text-align-center\" data-align=\"center\">Drill for <br>75% thread<\/th><th class=\"has-text-align-center\" data-align=\"center\">Drill for<br>50% thread<\/th><th class=\"has-text-align-center\" data-align=\"center\">Drill for<br>forming tap<\/th><th class=\"has-text-align-center\" data-align=\"center\">Drill for clearance<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">#000-120<\/td><td class=\"has-text-align-center\" data-align=\"center\">71<\/td><td class=\"has-text-align-center\" data-align=\"center\">69<\/td><td class=\"has-text-align-center\" data-align=\"center\">(70)<\/td><td class=\"has-text-align-center\" data-align=\"center\">62\u201365<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#00-90<\/td><td class=\"has-text-align-center\" data-align=\"center\">65<\/td><td class=\"has-text-align-center\" data-align=\"center\">60<\/td><td class=\"has-text-align-center\" data-align=\"center\">(62)<\/td><td class=\"has-text-align-center\" data-align=\"center\">54\u201355<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#0-80<\/td><td class=\"has-text-align-center\" data-align=\"center\">3\/64\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">55<\/td><td class=\"has-text-align-center\" data-align=\"center\">(54)<\/td><td class=\"has-text-align-center\" data-align=\"center\">52\u201350<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#2-56<\/td><td class=\"has-text-align-center\" data-align=\"center\">50<\/td><td class=\"has-text-align-center\" data-align=\"center\">49<\/td><td class=\"has-text-align-center\" data-align=\"center\">(5\/64\u201d)<\/td><td class=\"has-text-align-center\" data-align=\"center\">43\u201341<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#4-40<\/td><td class=\"has-text-align-center\" data-align=\"center\">43<\/td><td class=\"has-text-align-center\" data-align=\"center\">41<\/td><td class=\"has-text-align-center\" data-align=\"center\">39<\/td><td class=\"has-text-align-center\" data-align=\"center\">32\u201330<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#6-32<\/td><td class=\"has-text-align-center\" data-align=\"center\">36<\/td><td class=\"has-text-align-center\" data-align=\"center\">32<\/td><td class=\"has-text-align-center\" data-align=\"center\">1\/8\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">27\u201325<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#8-32<\/td><td class=\"has-text-align-center\" data-align=\"center\">29<\/td><td class=\"has-text-align-center\" data-align=\"center\">27<\/td><td class=\"has-text-align-center\" data-align=\"center\">25<\/td><td class=\"has-text-align-center\" data-align=\"center\">18\u201316<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#10-24<\/td><td class=\"has-text-align-center\" data-align=\"center\">25<\/td><td class=\"has-text-align-center\" data-align=\"center\">20<\/td><td class=\"has-text-align-center\" data-align=\"center\">11\/64\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">9\u20137<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#10-32<\/td><td class=\"has-text-align-center\" data-align=\"center\">21<\/td><td class=\"has-text-align-center\" data-align=\"center\">18<\/td><td class=\"has-text-align-center\" data-align=\"center\">16<\/td><td class=\"has-text-align-center\" data-align=\"center\">9\u20137<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#12-24<\/td><td class=\"has-text-align-center\" data-align=\"center\">16<\/td><td class=\"has-text-align-center\" data-align=\"center\">12<\/td><td class=\"has-text-align-center\" data-align=\"center\">9\u20138<\/td><td class=\"has-text-align-center\" data-align=\"center\">2\u20131<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">1\/4\u201d-20<\/td><td class=\"has-text-align-center\" data-align=\"center\">7<\/td><td class=\"has-text-align-center\" data-align=\"center\">7\/32\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">1<\/td><td class=\"has-text-align-center\" data-align=\"center\">17\/64\u201d\u20139\/32\u201d<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><em>Use 75% thread for aluminum, 50% for steel. Forming taps are specified for 65% thread.<\/em><\/p>\n\n\n\n<p><em>Parentheses indicate forming taps not available from McMaster.<\/em><\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"diameters\">Minor and major diameters of US screws<\/h2>\n\n\n\n<figure class=\"wp-block-table is-style-stripes\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Screw size<\/th><th class=\"has-text-align-center\" data-align=\"center\">Minor diam. (inch)<\/th><th class=\"has-text-align-center\" data-align=\"center\">Minor diam. (mm)<\/th><th class=\"has-text-align-center\" data-align=\"center\">Major diam. (inch)<\/th><th class=\"has-text-align-center\" data-align=\"center\">Major diam. (mm)<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">#000-120<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.0232\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.59<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.034\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.86<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#00-90<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.0326\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.83<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.047\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">1.19<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#0-80<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.045\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">1.14<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.060\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">1.52<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#2-56<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.070\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">1.78<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.086\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">2.18<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#4-40<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.089\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">2.26<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.112\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">2.84<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#6-32<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.100\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">2.54<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.138\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">3.51<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#8-32<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.126\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">3.20<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.164\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">4.17<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#10-24<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.139\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">3.53<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.190\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">4.83<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#10-32<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.152\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">3.86<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.190\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">4.83<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#12-24<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.165\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">4.19<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.216\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">5.49<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">1\/4\u201d-20<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.189\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">4.80<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.250\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">6.35<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"heads\">Head diameters of US screws<\/h2>\n\n\n\n<figure class=\"wp-block-table is-style-stripes\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Screw size<\/th><th class=\"has-text-align-center\" data-align=\"center\">Socket cap (inch)<\/th><th class=\"has-text-align-center\" data-align=\"center\">Socket cap (mm)<\/th><th class=\"has-text-align-center\" data-align=\"center\">Flat head (inch)<\/th><th class=\"has-text-align-center\" data-align=\"center\">Flat head (mm)<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">#000<\/td><td class=\"has-text-align-center\" data-align=\"center\">&#8211;<\/td><td class=\"has-text-align-center\" data-align=\"center\">&#8211;<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.061\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">1.55<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#00<\/td><td class=\"has-text-align-center\" data-align=\"center\">&#8211;<\/td><td class=\"has-text-align-center\" data-align=\"center\">&#8211;<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.089\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">2.26<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#0<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.096\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">2.44<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.112\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">2.84<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#2<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.140\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">3.56<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.162\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">4.11<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#4<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.183\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">4.65<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.212\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">5.38<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#6<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.226\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">5.74<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.262\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">6.65<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#8<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.270\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">6.86<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.312\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">7.92<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#10<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.312\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">7.92<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.362\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">9.19<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">#12<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.324\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">8.23<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.412\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">10.46<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">1\/4\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.375\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">9.52<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.477\u201d<\/td><td class=\"has-text-align-center\" data-align=\"center\">12.12<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><em>Flat head diameters apply to both 82\u00b0 and 100\u00b0 head angles.<\/em><\/p>\n\n\n\n<p><em>Socket cap head height is the same as major diameter for all sizes.<\/em><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Sources<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Forming taps: <a href=\"https:\/\/www.jarviscuttingtools.com\/forming-tap-drill-sizes\">Jarvis Cutting Tools<\/a><\/li>\n\n\n\n<li>Regular taps: <a href=\"http:\/\/www.shender4.com\/thread_chart.htm\">shender4.com<\/a><\/li>\n\n\n\n<li>Additional information from <a href=\"http:\/\/www.mcmaster.com\">McMaster<\/a>, <a href=\"https:\/\/www.newmantools.com\/taps\/micro.htm\">Newman Tools<\/a>, and <a href=\"https:\/\/amesweb.info\/Fasteners\/Machine-Screws\/No-0000-No-000-No-00-Thread-Dimensions.aspx\">Ames Web<\/a><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Imperial screws are designated by their diameter (in inches) and pitch (revolutions per inch). For instance, \u00bc-20 means: diameter 0.25\u201d, 20 threads per inch. Smaller screws are designated by a numerical gauge, larger numbers correspond to larger screws. On this page: Drills for screw holes Screw size Drill for 75% thread Drill for50% thread Drill [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-306","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/leech.caltech.edu\/cntl\/index.php?rest_route=\/wp\/v2\/pages\/306"}],"collection":[{"href":"https:\/\/leech.caltech.edu\/cntl\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/leech.caltech.edu\/cntl\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/leech.caltech.edu\/cntl\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/leech.caltech.edu\/cntl\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=306"}],"version-history":[{"count":4,"href":"https:\/\/leech.caltech.edu\/cntl\/index.php?rest_route=\/wp\/v2\/pages\/306\/revisions"}],"predecessor-version":[{"id":514,"href":"https:\/\/leech.caltech.edu\/cntl\/index.php?rest_route=\/wp\/v2\/pages\/306\/revisions\/514"}],"wp:attachment":[{"href":"https:\/\/leech.caltech.edu\/cntl\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=306"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}