{
 "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-end-fin-sleeve",
 "name": "Clamp-on hot-end fin sleeve for a 2 in tri-clamp tube (optional)",
 "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",
  "optional",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "clamp on fins tri clamp",
  "hot end fin sleeve"
 ],
 "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-end-fin-sleeve/",
 "sheet_txt": "https://xemstudio.com/objects/tri-clamp-hot-end-fin-sleeve/sheet.txt",
 "sheet": {
  "basis": "Design values: ring fins Ø76 × 1.5 at 5 pitch, two halves clamping the Ø50.8 tube",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Two halves with 14 ring fins that clamp onto the lower 66 mm of the closed-end spool with 4 × M4 × 16: the flame passes between the fins inside the shroud. The spool itself stays plain.",
   "Optional: without it the flame heats the bare tube; the analysis on the performance page assumes the inside wall at 800 K either way, and the sleeve is how a burner gets there with less flame."
  ],
  "table": {
   "columns": [
    "feature",
    "value"
   ],
   "rows": [
    [
     "fins",
     "14 × Ø76 × 1.5, pitch 5"
    ],
    [
     "bore",
     "Ø50.8 (clamp)"
    ],
    [
     "height",
     "2–68.5"
    ]
   ]
  }
 },
 "sheet_text": "Clamp-on hot-end fin sleeve for a 2 in tri-clamp tube (optional) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/tri-clamp-hot-end-fin-sleeve/  (CC BY 4.0)\nBasis: Design values: ring fins Ø76 × 1.5 at 5 pitch, two halves clamping the Ø50.8 tube\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Two halves with 14 ring fins that clamp onto the lower 66 mm of the closed-end spool with 4 × M4 × 16: the flame passes between the fins inside the shroud. The spool itself stays plain.\n- Optional: without it the flame heats the bare tube; the analysis on the performance page assumes the inside wall at 800 K either way, and the sleeve is how a burner gets there with less flame.\n\nfeature  value\nfins  14 × Ø76 × 1.5, pitch 5\nbore  Ø50.8 (clamp)\nheight  2–68.5\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-hot-end-fin-sleeve/index.json\nAPI: https://xemstudio.com/api/geometry?object=tri-clamp-hot-end-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-end-spool",
  "tri-clamp-split-burner-shroud",
  "list-fpse-generator-2in"
 ],
 "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",
   "mates": "hot spool tube OD",
   "fit": "clamp",
   "files": "all"
  },
  {
   "feature": "split",
   "exact": "1.0 total (0.5 per half)",
   "mates": "the other half",
   "fit": "clamp",
   "files": "all"
  },
  {
   "feature": "ear holes",
   "exact": "Ø4.5",
   "mates": "M4 clearance (ISO 273 medium)",
   "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": "Is it required?",
   "a": "No; it is a heat exchanger and every heat exchanger on this engine is optional."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "fin-sleeve-half-2in-76",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-hot-end-fin-sleeve/fin-sleeve-half-2in-76.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-hot-end-fin-sleeve/fin-sleeve-half-2in-76.stl",
   "note": "fin sleeve half (optional): bore Ø50.8 from 2 to 68.5 above the hot end, 14 ring fins Ø76 × 1.5 at 5 pitch, ears with 2 × M4 each side"
  }
 ],
 "markdown": "https://xemstudio.com/objects/tri-clamp-hot-end-fin-sleeve/index.md"
}