{
 "version": "2026-10-20",
 "license": "Dimension sheets are written by Xem Studio from the cited sources and are free to use (CC BY 4.0, attribute 'Xem Studio'). Linked files belong to their publishers under the license shown; Xem Studio does not host them. 'license_verified: false' means the license shown is from memory or the publisher's page as last read and should be confirmed at the link before commercial use.",
 "slug": "eccentric-strap",
 "name": "Split eccentric strap for Ø30 sheaves, 51 mm to the eye",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Drives & mechanisms",
 "year": null,
 "question": "What does an eccentric strap look like?",
 "tags": [
  "eccentric strap",
  "strap",
  "rod",
  "mechanism",
  "rotary to linear",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "eccentric strap",
  "eccentric rod strap",
  "split eccentric strap",
  "eccentric strap 30mm"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/eccentric-strap/",
 "sheet_txt": "https://xemstudio.com/objects/eccentric-strap/sheet.txt",
 "sheet": {
  "basis": "Ring Ø30 bore × Ø40 OD × 8 with a 1 mm split and a 40 × 10 arm ending in a Ø3 eye",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A ring Ø30 bore × Ø40 OD × 8 with a 1 mm split through the side opposite the arm, so it goes over the sheave without taking the shaft apart.",
   "A 40 × 10 arm ends in a Ø3 eye 51 mm from the ring's centre. Overall 75 × 40 × 8.",
   "The Ø30 bore turns on the sheave and a Ø3 pin in the eye drives the next link; fits are under Mating features."
  ],
  "table": {
   "columns": [
    "feature",
    "value_mm"
   ],
   "rows": [
    [
     "bore",
     "Ø30"
    ],
    [
     "ring OD",
     "Ø40"
    ],
    [
     "thickness",
     8
    ],
    [
     "split",
     1
    ],
    [
     "arm",
     "40 × 10"
    ],
    [
     "eye",
     "Ø3 at 51"
    ],
    [
     "overall",
     "75 × 40 × 8"
    ]
   ]
  }
 },
 "sheet_text": "Split eccentric strap for Ø30 sheaves, 51 mm to the eye — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/eccentric-strap/  (CC BY 4.0)\nBasis: Ring Ø30 bore × Ø40 OD × 8 with a 1 mm split and a 40 × 10 arm ending in a Ø3 eye\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A ring Ø30 bore × Ø40 OD × 8 with a 1 mm split through the side opposite the arm, so it goes over the sheave without taking the shaft apart.\n- A 40 × 10 arm ends in a Ø3 eye 51 mm from the ring's centre. Overall 75 × 40 × 8.\n- The Ø30 bore turns on the sheave and a Ø3 pin in the eye drives the next link; fits are under Mating features.\n\nfeature  value_mm\nbore  Ø30\nring OD  Ø40\nthickness  8\nsplit  1.0\narm  40 × 10\neye  Ø3 at 51\noverall  75 × 40 × 8\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Eccentric (mechanism) — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Eccentric_(mechanism)\n- Long Earth Society: Engine and rig builds on extrusion frames — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/eccentric-strap/index.json\nAPI: https://xemstudio.com/api/geometry?object=eccentric-strap\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Eccentric (mechanism)",
   "url": "https://en.wikipedia.org/wiki/Eccentric_(mechanism)",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Long Earth Society",
   "title": "Engine and rig builds on extrusion frames",
   "url": "https://longearthsociety.com/engineering/",
   "formats": [
    "web",
    "video"
   ],
   "license": "LES site",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "eccentric-sheaves",
  "four-bar-links",
  "pins-3mm",
  "clevis-pins"
 ],
 "fits": [
  {
   "role": "Goes in or on",
   "items": [
    {
     "slug": "eccentric-sheaves",
     "why": "Ø30 bore on the sheave"
    }
   ]
  },
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "four-bar-links",
     "why": "Ø3 eye to the link"
    }
   ]
  },
  {
   "role": "Also needed",
   "items": [
    {
     "slug": "pins-3mm",
     "why": "Ø3 pin in the eye"
    }
   ]
  }
 ],
 "dimensions": "exact (nominal, no printing tolerance)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. 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.",
 "mating": [
  {
   "feature": "strap bore",
   "exact": "Ø30",
   "mates": "Ø30 eccentric (turns in it)",
   "fit": "run",
   "files": "eccentric-strap-"
  },
  {
   "feature": "strap split",
   "exact": "1.0",
   "mates": "closes on the eccentric",
   "fit": "clamp",
   "files": "eccentric-strap-"
  },
  {
   "feature": "strap eye",
   "exact": "Ø3",
   "mates": "Ø3 pin (turns in it)",
   "fit": "run",
   "files": "eccentric-strap-"
  }
 ],
 "fit_classes": {
  "press": "stays put: pin, tube, bearing or magnet held by interference. Typical FDM: hole +0.0 to +0.1 mm on diameter.",
  "slide": "assembles by hand and is held by a grub, pinch or clamp: shaft in a hub, rod in a socket, spigot in a bore. Typical FDM: +0.2 mm.",
  "run": "turns or slides in use: pin in a link, rod through a guide. Typical FDM: +0.3 mm.",
  "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. Typical FDM: +0.3 mm.",
  "clamp": "split part that closes on the mating part with screws: make it at size.",
  "designed": "a gap that is part of the design (piston fit option, displacer gap, air gap): do not change."
 },
 "faq": [
  {
   "q": "How does the strap go on?",
   "a": "Through the 1 mm split, over the Ø30 sheave."
  },
  {
   "q": "Where is the strap eye?",
   "a": "Ø3, 51 mm from the strap centre."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "eccentric-strap-d30",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/eccentric-and-strap/eccentric-strap-d30.step",
   "stl": "https://xemstudio.com/files/hardware/eccentric-and-strap/eccentric-strap-d30.stl",
   "note": "split strap for the Ø30 eccentrics, Ø30 bore, 40 mm arm with a Ø3 eye"
  }
 ],
 "markdown": "https://xemstudio.com/objects/eccentric-strap/index.md"
}