{
 "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": "thermoacoustic-fin-sleeve",
 "name": "Thermoacoustic fin sleeve: clamp-on, 2 in tube, 34 mm (optional)",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Thermoacoustic & fluidyne",
 "year": null,
 "question": "How do I get more of a torch's heat into a 2 inch tube?",
 "tags": [
  "fins",
  "heat exchanger",
  "thermoacoustic",
  "clamp-on",
  "tri-clamp",
  "long earth society"
 ],
 "aliases": [
  "clamp on fin sleeve tube",
  "finned collar 2 inch tube",
  "hot end fins thermoacoustic"
 ],
 "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/thermoacoustic-fin-sleeve/",
 "sheet_txt": "https://xemstudio.com/objects/thermoacoustic-fin-sleeve/sheet.txt",
 "sheet": {
  "basis": "Bore = 2 in tube OD Ø50.8; length covers the 12 mm hot exchanger with 11 mm each side",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Two halves with 24 radial fins each side of the split, clamped round the plain core tube over the hot exchanger with one M4 × 16 and nut each side. The flame gas in the burner drum passes between the fins; the fins conduct into the tube wall, the wall into the slotted hot exchanger inside.",
   "Optional: the engine is complete without it (the drum then heats the bare tube); with it the tube wall reaches a given temperature with less flame.",
   "Fits: bore clamps the tube (1 mm split take-up); ear holes M4 clearance."
  ],
  "table": {
   "columns": [
    "feature",
    "value"
   ],
   "rows": [
    [
     "bore",
     "Ø50.8"
    ],
    [
     "fins",
     "24 × 1.5 to Ø72"
    ],
    [
     "length",
     "34"
    ]
   ]
  }
 },
 "sheet_text": "Thermoacoustic fin sleeve: clamp-on, 2 in tube, 34 mm (optional) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/thermoacoustic-fin-sleeve/  (CC BY 4.0)\nBasis: Bore = 2 in tube OD Ø50.8; length covers the 12 mm hot exchanger with 11 mm each side\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Two halves with 24 radial fins each side of the split, clamped round the plain core tube over the hot exchanger with one M4 × 16 and nut each side. The flame gas in the burner drum passes between the fins; the fins conduct into the tube wall, the wall into the slotted hot exchanger inside.\n- Optional: the engine is complete without it (the drum then heats the bare tube); with it the tube wall reaches a given temperature with less flame.\n- Fits: bore clamps the tube (1 mm split take-up); ear holes M4 clearance.\n\nfeature  value\nbore  Ø50.8\nfins  24 × 1.5 to Ø72\nlength  34\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Xem Studio: tools/gen_ta_power.py: the network model and every dimension on this page — code — CC BY 4.0 — https://xemstudio.com/\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/thermoacoustic-fin-sleeve/index.json\nAPI: https://xemstudio.com/api/geometry?object=thermoacoustic-fin-sleeve\n",
 "sources": [
  {
   "publisher": "Xem Studio",
   "title": "tools/gen_ta_power.py: the network model and every dimension on this page",
   "url": "https://xemstudio.com/",
   "formats": [
    "code"
   ],
   "license": "CC BY 4.0",
   "license_verified": true,
   "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": [
  "thermoacoustic-burner-drum",
  "thermoacoustic-slotted-exchanger-insert",
  "list-ta-ring-3x2in"
 ],
 "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": "2 in tube outside over the hot exchanger",
   "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"
  },
  {
   "feature": "fins",
   "exact": "24 × 1.5 to Ø72",
   "mates": "flame gas (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": "Why not weld fins on the spool?",
   "a": "A clamp-on sleeve keeps the spool a plain, orderable part and can be left off."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "fin-sleeve-half-2in-34",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/thermoacoustic-fin-sleeve/fin-sleeve-half-2in-34.step",
   "stl": "https://xemstudio.com/files/hardware/thermoacoustic-fin-sleeve/fin-sleeve-half-2in-34.stl",
   "note": "fin-sleeve half (y ≥ 0.5): bore Ø50.8, wall 3, 24 radial fins 1.5 thick to Ø72, 34 long; ears x ±27.9..44 with Ø4.5 at x ±40"
  }
 ],
 "markdown": "https://xemstudio.com/objects/thermoacoustic-fin-sleeve/index.md"
}