{
 "version": "2026-10-20",
 "license": "Dimension sheets: CC BY 4.0. Standard and published-size files: CC BY 4.0. Xem Studio's own designs (files_license = Xem Studio Design License): free to use and sell things from, not to redistribute as files — https://xemstudio.com/license/. Other publishers' files: their own license, linked beside them.",
 "slug": "chicago-screws-binding-posts",
 "name": "Chicago screws (binding posts, barrel bolts, sex bolts): barrel and head diameter, thread, hole size and lengths, 8-32 / 10-24 / 1/4-20",
 "kind": "standard",
 "category": "Hardware",
 "group": "Fasteners",
 "year": null,
 "question": "What size hole does a Chicago screw (binding post) need, and what are its barrel diameter, head diameter and lengths?",
 "tags": [
  "chicago screw",
  "binding post",
  "barrel bolt",
  "sex bolt",
  "screw post",
  "binder post",
  "leather rivet",
  "8-32 binding post",
  "fastener",
  "tote"
 ],
 "aliases": [
  "chicago screw dimensions",
  "chicago screw hole size",
  "binding post 8-32 dimensions",
  "sex bolt size chart",
  "chicago screw barrel diameter",
  "chicago screw 8-32 head diameter",
  "binder post hole size",
  "chicago screw lengths",
  "chicago screw 1/4 hole",
  "screw post leather dimensions",
  "barrel nut and screw sizes",
  "binding barrel dimensions"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "not-scanned",
 "les": false,
 "free_files": 0,
 "url": "https://xemstudio.com/objects/chicago-screws-binding-posts/",
 "sheet_txt": "https://xemstudio.com/objects/chicago-screws-binding-posts/sheet.txt",
 "sheet": {
  "basis": "Rivets Online (steel, three thread sizes), screwpost.com (aluminum 8-32) and McMaster-Carr's low-profile 8-32 table, as printed; maker / distributor numbers only, there is no standard behind these",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "There is no ASME or ISO standard for Chicago screws (also sold as binding posts, binder posts, barrel bolts, sex bolts or screw posts); each maker sets its own sizes and the makers below do not agree on head diameter. Check the part you buy.",
   "Rivets Online (steel): 8-32 barrel .203, head .415, hole 7/32; 10-24 barrel .250, head .438, hole 17/64; 1/4-20 barrel .312, head .562, hole 21/64. The page prints an 8-32 hole of '17/32 (.218)', which is a typo for 7/32 (.218) as its filter list says. The page's filter also lists a '10-24 with .262 body diameter' and does not say which of .250 and .262 belongs to which product.",
   "screwpost.com (aluminum): 3/16 post, 8-32, 7/16 head on both post and screw, 'fits in a 1/4 inch hole'. McMaster-Carr (aluminum, low profile): barrel 13/64, head 13/32 x 1/16, screw head 13/32 x 1/16. For 8-32 the three makers give heads of 0.415, 0.4375 and 0.406 in and barrels of 0.203, 0.1875 and 0.203 in.",
   "Lengths are barrel (post) lengths under the head, matched to the material thickness (grip) the barrel clamps; the screw is shorter than the post. The McMaster table rows are for 1/8 to 1 in material in 7 steps.",
   "No file: the thread depth, the head profile (flat / dome) and the screw tip are not given as numbers in the sources read, so a model would be invented. McMaster-Carr sells binding barrels and screws with per-part STEP; linked, not copied."
  ],
  "table": {
   "columns": [
    "source",
    "thread",
    "barrel dia (in)",
    "head dia (in)",
    "hole (in)",
    "barrel (post) lengths (in)",
    "screw lengths (in)",
    "note"
   ],
   "rows": [
    [
     "Rivets Online, steel",
     "8-32",
     ".203",
     ".415",
     "7/32 (.218)",
     "3/16, 1/4, 3/8, 1/2, 5/8, 3/4, 1, 1-1/4, 1-1/2, 1-3/4, 2",
     "1/4, 3/8",
     "page also prints a 17/32 hole for this row; .218 and the filter list 7/32"
    ],
    [
     "Rivets Online, steel",
     "10-24",
     ".250 (page filter also lists a .262 body)",
     ".438",
     "17/64 (.265)",
     "1/4, 3/8, 1/2, 5/8, 3/4, 1, 1-1/4, 1-1/2, 2",
     "5/16",
     "extension: 10-24, 1/2 long, 1/4 diameter, 17/64 hole"
    ],
    [
     "Rivets Online, steel",
     "1/4-20",
     ".312",
     ".562",
     "21/64 (.328)",
     "3/8, 1/2, 5/8, 3/4, 1, 1-1/4, 1-1/2, 2",
     "5/16",
     ""
    ],
    [
     "screwpost.com, aluminum",
     "8-32",
     "3/16 (0.1875)",
     "7/16 (0.4375)",
     "fits a 1/4 hole",
     "sizes by material thickness 1/8 to 6 in; posts 3/8 and under are tapped through",
     "—",
     "head dia is the same on post and screw; extensions 1/4, 1/2, 3/4, 1"
    ],
    [
     "McMaster-Carr low-profile, 6063 aluminum, slotted",
     "8-32",
     "13/64",
     "13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)",
     "not listed",
     "barrel 1/8 (for material 1/8 to 3/16)",
     "screw 3/16",
     "thread depth 3/16"
    ],
    [
     "McMaster-Carr low-profile, 6063 aluminum, slotted",
     "8-32",
     "13/64",
     "13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)",
     "not listed",
     "barrel 3/16 (for material 3/16 to 1/4)",
     "screw 1/4",
     "thread depth 1/4"
    ],
    [
     "McMaster-Carr low-profile, 6063 aluminum, slotted",
     "8-32",
     "13/64",
     "13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)",
     "not listed",
     "barrel 1/4 (for material 1/4 to 3/8)",
     "screw 1/4",
     "thread depth 1/4"
    ],
    [
     "McMaster-Carr low-profile, 6063 aluminum, slotted",
     "8-32",
     "13/64",
     "13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)",
     "not listed",
     "barrel 3/8 (for material 3/8 to 5/8)",
     "screw 3/8",
     "thread depth 3/8"
    ],
    [
     "McMaster-Carr low-profile, 6063 aluminum, slotted",
     "8-32",
     "13/64",
     "13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)",
     "not listed",
     "barrel 1/2 (for material 1/2 to 3/4)",
     "screw 3/8",
     "thread depth 3/8"
    ],
    [
     "McMaster-Carr low-profile, 6063 aluminum, slotted",
     "8-32",
     "13/64",
     "13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)",
     "not listed",
     "barrel 5/8 (for material 5/8 to 7/8)",
     "screw 3/8",
     "thread depth 3/8"
    ],
    [
     "McMaster-Carr low-profile, 6063 aluminum, slotted",
     "8-32",
     "13/64",
     "13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)",
     "not listed",
     "barrel 3/4 (for material 3/4 to 1)",
     "screw 3/8",
     "thread depth 3/8"
    ]
   ]
  }
 },
 "sheet_text": "Chicago screws (binding posts, barrel bolts, sex bolts): barrel and head diameter, thread, hole size and lengths, 8-32 / 10-24 / 1/4-20 — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/chicago-screws-binding-posts/  (sheet CC BY 4.0)\nBasis: Rivets Online (steel, three thread sizes), screwpost.com (aluminum 8-32) and McMaster-Carr's low-profile 8-32 table, as printed; maker / distributor numbers only, there is no standard behind these\nCatalog version: 2026-10-20\n\nSizes: see table below\n- There is no ASME or ISO standard for Chicago screws (also sold as binding posts, binder posts, barrel bolts, sex bolts or screw posts); each maker sets its own sizes and the makers below do not agree on head diameter. Check the part you buy.\n- Rivets Online (steel): 8-32 barrel .203, head .415, hole 7/32; 10-24 barrel .250, head .438, hole 17/64; 1/4-20 barrel .312, head .562, hole 21/64. The page prints an 8-32 hole of '17/32 (.218)', which is a typo for 7/32 (.218) as its filter list says. The page's filter also lists a '10-24 with .262 body diameter' and does not say which of .250 and .262 belongs to which product.\n- screwpost.com (aluminum): 3/16 post, 8-32, 7/16 head on both post and screw, 'fits in a 1/4 inch hole'. McMaster-Carr (aluminum, low profile): barrel 13/64, head 13/32 x 1/16, screw head 13/32 x 1/16. For 8-32 the three makers give heads of 0.415, 0.4375 and 0.406 in and barrels of 0.203, 0.1875 and 0.203 in.\n- Lengths are barrel (post) lengths under the head, matched to the material thickness (grip) the barrel clamps; the screw is shorter than the post. The McMaster table rows are for 1/8 to 1 in material in 7 steps.\n- No file: the thread depth, the head profile (flat / dome) and the screw tip are not given as numbers in the sources read, so a model would be invented. McMaster-Carr sells binding barrels and screws with per-part STEP; linked, not copied.\n\nsource  thread  barrel dia (in)  head dia (in)  hole (in)  barrel (post) lengths (in)  screw lengths (in)  note\nRivets Online, steel  8-32  .203  .415  7/32 (.218)  3/16, 1/4, 3/8, 1/2, 5/8, 3/4, 1, 1-1/4, 1-1/2, 1-3/4, 2  1/4, 3/8  page also prints a 17/32 hole for this row; .218 and the filter list 7/32\nRivets Online, steel  10-24  .250 (page filter also lists a .262 body)  .438  17/64 (.265)  1/4, 3/8, 1/2, 5/8, 3/4, 1, 1-1/4, 1-1/2, 2  5/16  extension: 10-24, 1/2 long, 1/4 diameter, 17/64 hole\nRivets Online, steel  1/4-20  .312  .562  21/64 (.328)  3/8, 1/2, 5/8, 3/4, 1, 1-1/4, 1-1/2, 2  5/16  \nscrewpost.com, aluminum  8-32  3/16 (0.1875)  7/16 (0.4375)  fits a 1/4 hole  sizes by material thickness 1/8 to 6 in; posts 3/8 and under are tapped through  —  head dia is the same on post and screw; extensions 1/4, 1/2, 3/4, 1\nMcMaster-Carr low-profile, 6063 aluminum, slotted  8-32  13/64  13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)  not listed  barrel 1/8 (for material 1/8 to 3/16)  screw 3/16  thread depth 3/16\nMcMaster-Carr low-profile, 6063 aluminum, slotted  8-32  13/64  13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)  not listed  barrel 3/16 (for material 3/16 to 1/4)  screw 1/4  thread depth 1/4\nMcMaster-Carr low-profile, 6063 aluminum, slotted  8-32  13/64  13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)  not listed  barrel 1/4 (for material 1/4 to 3/8)  screw 1/4  thread depth 1/4\nMcMaster-Carr low-profile, 6063 aluminum, slotted  8-32  13/64  13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)  not listed  barrel 3/8 (for material 3/8 to 5/8)  screw 3/8  thread depth 3/8\nMcMaster-Carr low-profile, 6063 aluminum, slotted  8-32  13/64  13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)  not listed  barrel 1/2 (for material 1/2 to 3/4)  screw 3/8  thread depth 3/8\nMcMaster-Carr low-profile, 6063 aluminum, slotted  8-32  13/64  13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)  not listed  barrel 5/8 (for material 5/8 to 7/8)  screw 3/8  thread depth 3/8\nMcMaster-Carr low-profile, 6063 aluminum, slotted  8-32  13/64  13/32 (barrel head, 1/16 high; screw head 13/32 x 1/16)  not listed  barrel 3/4 (for material 3/4 to 1)  screw 3/8  thread depth 3/8\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Rivets Online: Binder post and screws (Chicago screws), steel: barrel diameter, head diameter, thread, hole size, post and screw lengths for 8-32, 10-24 and 1/4-20 — web — Maker/distributor page; numbers only — https://www.rivetsonline.com/binder-post-barrel-nuts-chicago-screws/steel-post-and-screws-chicago-screws-barrel-nuts\n- screwpost.com: Aluminum screw posts (Chicago screws): 3/16 post, 8-32, 7/16 head, 1/4 hole; sizes by material thickness — web — Maker/distributor page; numbers only — https://www.screwpost.com/index.php?cPath=1\n- McMaster-Carr: Aluminum low-profile binding barrels and screws, 8-32: material thickness, barrel length, barrel and screw head dimensions (page table as printed) — web — Distributor catalog page; numbers only — https://www.mcmaster.com/aluminum-binding-bolts\n\nNo true-size file yet: the published figures do not fix the whole shape; a measured scan is planned.\nAPI: https://xemstudio.com/api/geometry?object=chicago-screws-binding-posts\n",
 "sources": [
  {
   "publisher": "Rivets Online",
   "title": "Binder post and screws (Chicago screws), steel: barrel diameter, head diameter, thread, hole size, post and screw lengths for 8-32, 10-24 and 1/4-20",
   "url": "https://www.rivetsonline.com/binder-post-barrel-nuts-chicago-screws/steel-post-and-screws-chicago-screws-barrel-nuts",
   "formats": [
    "web"
   ],
   "license": "Maker/distributor page; numbers only",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "screwpost.com",
   "title": "Aluminum screw posts (Chicago screws): 3/16 post, 8-32, 7/16 head, 1/4 hole; sizes by material thickness",
   "url": "https://www.screwpost.com/index.php?cPath=1",
   "formats": [
    "web"
   ],
   "license": "Maker/distributor page; numbers only",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "McMaster-Carr",
   "title": "Aluminum low-profile binding barrels and screws, 8-32: material thickness, barrel length, barrel and screw head dimensions (page table as printed)",
   "url": "https://www.mcmaster.com/aluminum-binding-bolts",
   "formats": [
    "web"
   ],
   "license": "Distributor catalog page; numbers only",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "not-scanned",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "imperial-machine-screws",
  "rivet-nuts-flat-head",
  "blind-pop-rivets-dome-head",
  "screw-on-rubber-feet-and-bumpers",
  "hex-nuts-inch"
 ],
 "fits": [],
 "dimensions": "exact (nominal, no tolerance added)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no tolerance added. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn. Typical accuracy by process and ISO 286 fits: https://xemstudio.com/tolerances/",
 "mating": [],
 "faq": [
  {
   "q": "What size hole does an 8-32 Chicago screw need?",
   "a": "Rivets Online lists a 7/32 in (0.218 in) hole for its 8-32 steel binder post (barrel .203 in); screwpost.com says its 3/16 in aluminum post 'fits in a 1/4 inch hole'. McMaster-Carr does not list a hole for its 13/64 in low-profile barrel."
  },
  {
   "q": "What are the common Chicago screw thread sizes?",
   "a": "8-32 is the common one (screwpost.com calls it the industry standard); Rivets Online also lists 10-24 and 1/4-20."
  },
  {
   "q": "Is a Chicago screw the same as a sex bolt?",
   "a": "Both names are used for a barrel (post) that a screw threads into; sellers file them together (barrel bolts and screws, binding barrels). Sizes are per maker, with no standard."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/chicago-screws-binding-posts/index.md"
}