{
 "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-hot-fin-sleeve",
 "name": "Hot-end fin sleeve for a 2 in tri-clamp cup: slide-on ring fins, set-screw held",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Stirling & thermoacoustic",
 "year": null,
 "question": "How do I put fins on the hot end of a tri-clamp Stirling engine without a custom finned fitting?",
 "tags": [
  "fins",
  "heat exchanger",
  "hot end",
  "sleeve",
  "optional",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "stirling hot end fins",
  "slide on fins 2 inch tube",
  "tri clamp hot end heat exchanger",
  "finned sleeve 50.8",
  "flame fins stirling"
 ],
 "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-hot-fin-sleeve/",
 "sheet_txt": "https://xemstudio.com/objects/tri-clamp-hot-fin-sleeve/sheet.txt",
 "sheet": {
  "basis": "ASME BPE 2 in tube OD Ø50.8 (the sleeve's bore); fin size and pitch are design values from the sealed generator layout; M4 set screws ISO 4026",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A separate heat exchanger for the closed hot end of a plain 2 in cup: a sleeve whose bore is exactly the tube's Ø50.8 slides over the closed end, nine Ø80 ring fins catch the flame gas, and three M4 set screws in a band above the fins hold it. The cup stays a plain, standard closed-end spool; the sleeve can be made any way you like.",
   "On the sealed generator it sits on the cup-2in-150 from 1.5 mm above the outer bottom (clear of the 1.5 mm round) to 7 mm above the top fin, 49.0 mm in all; the fins cover the bottom 43.5 mm, inside the burner shroud, 4 mm from the shroud's wall.",
   "The fins are Ø80 so that, starting from the sleeve's Ø56.8 hub, they have the same area as Ø76 fins grown straight off the tube.",
   "It is optional: the engine runs on the bare cup with less power. The set screws line up with three of the shroud's exhaust windows, so they can be reached with the shroud in place.",
   "Fits: the bore slides on the tube OD (slide fit), the set screws clamp it."
  ],
  "table": {
   "columns": [
    "feature",
    "value"
   ],
   "rows": [
    [
     "bore",
     "Ø50.8 (tube OD)"
    ],
    [
     "length",
     49
    ],
    [
     "wall",
     3
    ],
    [
     "fins",
     "9 × Ø80 × 1.5, 5 pitch"
    ],
    [
     "set screws",
     "3 × M4, 0 / 120 / 240°"
    ],
    [
     "fits",
     "cup-2in-150 (and any 2 in tube)"
    ]
   ]
  }
 },
 "sheet_text": "Hot-end fin sleeve for a 2 in tri-clamp cup: slide-on ring fins, set-screw held — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/tri-clamp-hot-fin-sleeve/  (CC BY 4.0)\nBasis: ASME BPE 2 in tube OD Ø50.8 (the sleeve's bore); fin size and pitch are design values from the sealed generator layout; M4 set screws ISO 4026\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A separate heat exchanger for the closed hot end of a plain 2 in cup: a sleeve whose bore is exactly the tube's Ø50.8 slides over the closed end, nine Ø80 ring fins catch the flame gas, and three M4 set screws in a band above the fins hold it. The cup stays a plain, standard closed-end spool; the sleeve can be made any way you like.\n- On the sealed generator it sits on the cup-2in-150 from 1.5 mm above the outer bottom (clear of the 1.5 mm round) to 7 mm above the top fin, 49.0 mm in all; the fins cover the bottom 43.5 mm, inside the burner shroud, 4 mm from the shroud's wall.\n- The fins are Ø80 so that, starting from the sleeve's Ø56.8 hub, they have the same area as Ø76 fins grown straight off the tube.\n- It is optional: the engine runs on the bare cup with less power. The set screws line up with three of the shroud's exhaust windows, so they can be reached with the shroud in place.\n- Fits: the bore slides on the tube OD (slide fit), the set screws clamp it.\n\nfeature  value\nbore  Ø50.8 (tube OD)\nlength  49.0\nwall  3.0\nfins  9 × Ø80 × 1.5, 5 pitch\nset screws  3 × M4, 0 / 120 / 240°\nfits  cup-2in-150 (and any 2 in tube)\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- ISO (via iTeh sample): ISO 2852 clamp liners: face profile and flange / groove diameters — PDF — standard excerpt; dimensions are facts — https://cdn.standards.iteh.ai/samples/7850/eb49c396488d408c8ced3e2961d76cf3/ISO-2852-1974.pdf\n- ASME: BPE Bioprocessing Equipment (clamp fitting dimensions, tube OD and wall) — standard — ASME; dimensions are facts [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment\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-hot-fin-sleeve/index.json\nAPI: https://xemstudio.com/api/geometry?object=tri-clamp-hot-fin-sleeve\n",
 "sources": [
  {
   "publisher": "ISO (via iTeh sample)",
   "title": "ISO 2852 clamp liners: face profile and flange / groove diameters",
   "url": "https://cdn.standards.iteh.ai/samples/7850/eb49c396488d408c8ced3e2961d76cf3/ISO-2852-1974.pdf",
   "formats": [
    "PDF"
   ],
   "license": "standard excerpt; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "ASME",
   "title": "BPE Bioprocessing Equipment (clamp fitting dimensions, tube OD and wall)",
   "url": "https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment",
   "formats": [
    "standard"
   ],
   "license": "ASME; dimensions are facts",
   "license_verified": false,
   "hosted": false
  },
  {
   "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-cups",
  "tri-clamp-burner-shroud",
  "tri-clamp-jacket-shell",
  "set-screws-metric",
  "list-tri-clamp-sealed-diaphragm-generator"
 ],
 "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 = the 2 in tube OD",
   "mates": "cup-2in-150 tube OD (over its closed end)",
   "fit": "slide",
   "files": "all"
  },
  {
   "feature": "set-screw holes",
   "exact": "3 × Ø3.3 at 0 / 120 / 240°",
   "mates": "M4 tap drill; M4 × 4 set screws onto the tube OD",
   "fit": "clamp",
   "files": "all"
  },
  {
   "feature": "fins",
   "exact": "9 × Ø80 × 1.5 at 5 pitch",
   "mates": "burner shroud Ø88 bore: 4 mm gas annulus",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "top band to the shroud lid",
   "exact": "1.0",
   "mates": "shroud lid (no contact)",
   "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": "Do I need it?",
   "a": "No. It is an optional heat exchanger; without it the flame heats the bare cup and the engine makes less power."
  },
  {
   "q": "Why not fins on the cup itself?",
   "a": "A sanitary fabricator makes plain spools and closed-end cups from stock tube; fins built onto one are not something they make. A separate sleeve keeps the cup standard and lets the fins be made any way."
  },
  {
   "q": "How is it held?",
   "a": "Three M4 set screws onto the tube OD; its bore is the tube OD exactly (slide fit)."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "hot-fin-sleeve-2in-80x9",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-hot-fin-sleeve/hot-fin-sleeve-2in-80x9.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-hot-fin-sleeve/hot-fin-sleeve-2in-80x9.stl",
   "note": "hot-end fin sleeve for the 2 in tube: bore Ø50.8 (the tube OD) × 49.0, 3 mm wall, 9 ring fins Ø80 × 1.5 at 5 pitch, 7 mm band over the top fin with 3 × M4 tapped (Ø3.3) at 0 / 120 / 240°"
  }
 ],
 "markdown": "https://xemstudio.com/objects/tri-clamp-hot-fin-sleeve/index.md"
}