{
 "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": "tri-clamp-ring-fin-sleeve",
 "name": "Slip-on fin sleeve for a 2 in closed hot end (nine Ø76 ring fins)",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Stirling & thermoacoustic",
 "year": null,
 "question": "How do I add fins to a plain tri-clamp hot end?",
 "tags": [
  "fins",
  "heat exchanger",
  "hot end",
  "sleeve",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "stirling hot end fins",
  "slip on fin sleeve tri clamp"
 ],
 "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/tri-clamp-ring-fin-sleeve/",
 "sheet_txt": "https://xemstudio.com/objects/tri-clamp-ring-fin-sleeve/sheet.txt",
 "sheet": {
  "basis": "Design values; fin set as the finned hot head on this site so the same burner shroud fits",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A separate part: a finned cup that slides over the closed end of a 2 in hot spool and sits on it. Bore Ø50.8 (the tube's OD) and an inside bottom shaped to the closed end, so the heat crosses where they touch. Nine Ø76 × 1.5 ring fins at 5 mm pitch take the flame's heat in the burner shroud.",
   "Optional: the engine runs without it at a lower hot-wall temperature for the same flame."
  ],
  "table": {
   "columns": [
    "feature",
    "value"
   ],
   "rows": [
    [
     "bore",
     "Ø50.8"
    ],
    [
     "depth",
     45
    ],
    [
     "fins",
     "9 × Ø76 × 1.5, 5 pitch"
    ]
   ]
  }
 },
 "sheet_text": "Slip-on fin sleeve for a 2 in closed hot end (nine Ø76 ring fins) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/tri-clamp-ring-fin-sleeve/  (CC BY 4.0)\nBasis: Design values; fin set as the finned hot head on this site so the same burner shroud fits\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A separate part: a finned cup that slides over the closed end of a 2 in hot spool and sits on it. Bore Ø50.8 (the tube's OD) and an inside bottom shaped to the closed end, so the heat crosses where they touch. Nine Ø76 × 1.5 ring fins at 5 mm pitch take the flame's heat in the burner shroud.\n- Optional: the engine runs without it at a lower hot-wall temperature for the same flame.\n\nfeature  value\nbore  Ø50.8\ndepth  45.0\nfins  9 × Ø76 × 1.5, 5 pitch\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Long Earth Society: Engine builds — 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/tri-clamp-ring-fin-sleeve/index.json\nAPI: https://xemstudio.com/api/geometry?object=tri-clamp-ring-fin-sleeve\n",
 "sources": [
  {
   "publisher": "Long Earth Society",
   "title": "Engine builds",
   "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": [
  "tri-clamp-closed-hot-spool-bored",
  "tri-clamp-burner-shroud",
  "tri-clamp-horizontal-burner-shroud",
  "list-tri-clamp-horizontal-gamma",
  "list-tri-clamp-charged-beta"
 ],
 "fits": [],
 "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": "bore",
   "exact": "Ø50.8 with a 1.5 inner round at the bottom",
   "mates": "2 in tube OD and closed end",
   "fit": "slide",
   "files": "all"
  },
  {
   "feature": "fins",
   "exact": "9 × Ø76 × 1.5, 5 pitch",
   "mates": "burner shroud Ø88 bore (gas annulus)",
   "fit": "designed",
   "files": "all"
  }
 ],
 "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": "Does it have to be a press fit?",
   "a": "No: it slides on and sits on the closed end; at temperature the fit closes up if the sleeve grows less than the tube."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "fin-sleeve-2in-9x76",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-ring-fin-sleeve/fin-sleeve-2in-9x76.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-ring-fin-sleeve/fin-sleeve-2in-9x76.stl",
   "note": "slip-on hot-end fin sleeve for a 2 in closed end: cup, bore Ø50.8 with the closed end's 1.5 round inside its bottom, wall 2, bottom 2, 45.0 deep; 9 ring fins Ø76 × 1.5 at 5 pitch"
  }
 ],
 "markdown": "https://xemstudio.com/objects/tri-clamp-ring-fin-sleeve/index.md"
}