{
 "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-shroud-fin-sleeve",
 "name": "Thermoacoustic fin sleeve for the flame-shroud band: 2 in tube, 34 mm, fins to Ø72, ears inside Ø73",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Thermoacoustic & fluidyne",
 "year": null,
 "question": "What fin sleeve fits inside the thermoacoustic flame shroud?",
 "tags": [
  "fin sleeve",
  "hot exchanger",
  "thermoacoustic",
  "heat exchanger",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "fin sleeve inside burner shroud",
  "thermoacoustic hot fin sleeve 2 inch",
  "clamp on fins 2 inch tube"
 ],
 "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-shroud-fin-sleeve/",
 "sheet_txt": "https://xemstudio.com/objects/thermoacoustic-shroud-fin-sleeve/sheet.txt",
 "sheet": {
  "basis": "Design values: the band of ta-shroud-2in-front / -back is Ø75 inside (r 37.5) and 35 between its end walls; the sleeve, its ears, M4 heads and nuts stay inside r 37",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Two halves clamped round a plain 2 in tube over a hot exchanger, inside the flame shroud's band: the flame gas from the flue passes between the fins, the fins conduct into the tube wall and the wall into the exchanger inside.",
   "Everything stays inside the band: fins to r 36, ears to r 36, the M4 × 12 head and nut at x ±32 inside r 37; 34 long in the band's 35. No fin within ±20° of the ears, so the screw head and nut have room.",
   "Optional: the engine runs without it (the flame heats the bare tube). Fits: bore clamps the tube (1 mm split take-up); ear holes M4 clearance."
  ],
  "table": {
   "columns": [
    "part",
    "bore_mm",
    "length_mm",
    "fins",
    "fin_tip_dia_mm",
    "ears_to_r_mm",
    "screws"
   ],
   "rows": [
    [
     "ta-fin-sleeve-half-2in-34-r36",
     50.8,
     34,
     "20 per sleeve, 1.5 thick",
     72,
     36,
     "2 × M4 × 12 + nuts"
    ]
   ]
  }
 },
 "sheet_text": "Thermoacoustic fin sleeve for the flame-shroud band: 2 in tube, 34 mm, fins to Ø72, ears inside Ø73 — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/thermoacoustic-shroud-fin-sleeve/  (CC BY 4.0)\nBasis: Design values: the band of ta-shroud-2in-front / -back is Ø75 inside (r 37.5) and 35 between its end walls; the sleeve, its ears, M4 heads and nuts stay inside r 37\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Two halves clamped round a plain 2 in tube over a hot exchanger, inside the flame shroud's band: the flame gas from the flue passes between the fins, the fins conduct into the tube wall and the wall into the exchanger inside.\n- Everything stays inside the band: fins to r 36, ears to r 36, the M4 × 12 head and nut at x ±32 inside r 37; 34 long in the band's 35. No fin within ±20° of the ears, so the screw head and nut have room.\n- Optional: the engine runs without it (the flame heats the bare tube). Fits: bore clamps the tube (1 mm split take-up); ear holes M4 clearance.\n\npart  bore_mm  length_mm  fins  fin_tip_dia_mm  ears_to_r_mm  screws\nta-fin-sleeve-half-2in-34-r36  50.8  34.0  20 per sleeve, 1.5 thick  72.0  36.0  2 × M4 × 12 + nuts\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Xem Studio: tools/gen_ta_modular.py: the section geometry, the network model and every number on these pages — 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-shroud-fin-sleeve/index.json\nAPI: https://xemstudio.com/api/geometry?object=thermoacoustic-shroud-fin-sleeve\n",
 "sources": [
  {
   "publisher": "Xem Studio",
   "title": "tools/gen_ta_modular.py: the section geometry, the network model and every number on these pages",
   "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": [
  "list-ta-modular-free-piston-2in",
  "thermoacoustic-hot-shroud",
  "thermoacoustic-fin-sleeve",
  "tri-clamp-closed-end-spool"
 ],
 "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 at x ±32",
   "mates": "M4 clearance (ISO 273 medium)",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "fins and ears",
   "exact": "to r 36",
   "mates": "flame shroud band's chamber wall at r 37.5 (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 the other fin sleeves?",
   "a": "Their ears reach r 44, through the band's wall; this one keeps everything inside the band."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "ta-fin-sleeve-half-2in-34-r36",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/thermoacoustic-shroud-fin-sleeve/ta-fin-sleeve-half-2in-34-r36.step",
   "stl": "https://xemstudio.com/files/hardware/thermoacoustic-shroud-fin-sleeve/ta-fin-sleeve-half-2in-34-r36.stl",
   "note": "fin-sleeve half (y ≥ 0.5): bore Ø50.8, wall 3, radial fins 1.5 thick to Ø72 every 15° (none within ±20° of the ears), 34 long; ears x ±27.9..36 with Ø4.5 at x ±32: fits inside the flame shroud's band"
  }
 ],
 "markdown": "https://xemstudio.com/objects/thermoacoustic-shroud-fin-sleeve/index.md"
}