{
 "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": "list-tri-clamp-rd-beta",
 "name": "Build list: Tri-clamp rolling-diaphragm beta, 2 in",
 "kind": "list",
 "category": "Stirling engines",
 "group": "Guide",
 "year": null,
 "question": "What parts do I need to build a Tri-clamp rolling-diaphragm beta, 2 in?",
 "tags": [
  "list",
  "build",
  "stirling",
  "long earth society",
  "tri-clamp",
  "diaphragm",
  "beta",
  "rolling diaphragm",
  "torch"
 ],
 "aliases": [
  "rolling diaphragm stirling",
  "tri clamp beta stirling",
  "rolling diaphragm beta engine",
  "torch stirling tri clamp",
  "tri clamp stirling build list"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "not-scanned",
 "les": true,
 "free_files": 0,
 "url": "https://xemstudio.com/objects/list-tri-clamp-rd-beta/",
 "sheet_txt": "https://xemstudio.com/objects/list-tri-clamp-rd-beta/sheet.txt",
 "sheet": {
  "basis": "Every part is a free STEP/STL on this site or a standard part with its own page; quantities are the full count, every screw, nut, pin, gasket and clamp.",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A torch-heated beta in two pieces of pressure vessel: a 2 in × 150 cup with the displacer, and the rolling-diaphragm power head straight on top of it, the displacer rod running up through the power piston.",
   "Numbers: Numbers (with the optional finned cooler; cold end taken at 320 K): power swept 20.0 mL, displacer swept 33.2 mL, dead volume 38 mL (swept/dead 0.52); Schmidt work at 650 / 320 K and 1 bar mean 0.47 J per turn (1.57 pressure ratio, ±23 kPa); shaft power about 0.6–2.3 W at 300–600 rpm (0.25–0.5 of Schmidt)."
  ],
  "table": {
   "columns": [
    "subsystem",
    "object",
    "parts",
    "qty",
    "note"
   ],
   "rows": [
    [
     null,
     "tri-clamp-rd-engine-frame",
     "rd-frame-2in",
     1,
     "base, wall, gussets"
    ],
    [
     null,
     "tri-clamp-torch-stand",
     "torch-stand-40",
     1,
     "on the base, post toward +Y; the heat source is a torch flame 40 mm under the cup"
    ],
    [
     null,
     "socket-head-cap-screws-metric",
     "shcs-m4x10",
     2,
     "torch stand to the base"
    ],
    [
     null,
     "set-screws-metric",
     "set-m4x10",
     3,
     "centre the torch head in the stand ring"
    ],
    [
     null,
     "tri-clamp-cups",
     "cup-2in-150",
     1,
     "the hot end and displacer cylinder in one piece: no joint near the flame"
    ],
    [
     null,
     "spool-hanger-collars",
     "hanger-2in-tab",
     1,
     "on the cup under the top clamp; bar to the wall"
    ],
    [
     null,
     "spool-hanger-collars",
     "hanger-2in-plain",
     1,
     "closes the hanger"
    ],
    [
     null,
     "socket-head-cap-screws-metric",
     "shcs-m5x25",
     2,
     "hanger bar through the wall"
    ],
    [
     null,
     "socket-head-cap-screws-metric",
     "shcs-m4x20",
     2,
     "hanger ears"
    ],
    [
     null,
     "hex-nuts-metric",
     "nut-m4",
     2,
     "hanger ears"
    ],
    [
     null,
     "tri-clamp-finned-cooler",
     "cooler-half-2in-56",
     2,
     "optional: clamp-on fin halves on the cup under the hanger (the cold end of the displacer cylinder); without them the engine runs with less power, or cool that part of the cup any way you like"
    ],
    [
     null,
     "socket-head-cap-screws-metric",
     "shcs-m4x30",
     4,
     "optional: cooler ears (only with the cooler)"
    ],
    [
     null,
     "hex-nuts-metric",
     "nut-m4",
     4,
     "optional: cooler ears (only with the cooler)"
    ],
    [
     null,
     "rolling-diaphragm-top-hat",
     "rd-diaphragm-1.50-h1.50",
     1,
     "1.50 in bore, 1.50 in high, flat flange: clamped in the joint in place of a gasket"
    ],
    [
     null,
     "tri-clamp-rd-power-head",
     "rd-power-head-2in",
     1,
     "standard 2 in clamp face, Ø38.10 cylinder, bushing seat, crank tower"
    ],
    [
     null,
     "tri-clamp-rd-power-head",
     "rd-seat-ring-2in",
     1,
     "in the head's face recess, behind the diaphragm flange"
    ],
    [
     null,
     "tri-clamp-clamps",
     "clamp-half-2in",
     2,
     "1 joint, two halves each"
    ],
    [
     null,
     "socket-head-cap-screws-metric",
     "shcs-m5x30",
     2,
     "clamp bolts"
    ],
    [
     null,
     "hex-nuts-metric",
     "nut-m5",
     4,
     "clamp nuts (2), hanger bar (2)"
    ],
    [
     null,
     "sleeve-bushings",
     "bushing-5x8x12",
     2,
     "back to back in the head's Ø8 seat: guide the tube rod"
    ],
    [
     null,
     "tri-clamp-rd-piston",
     "rd-piston-2in",
     1,
     "Ø33.27, never touches the bore"
    ],
    [
     null,
     "tri-clamp-rd-piston",
     "rd-retainer-26-gland3",
     1,
     "clamps the diaphragm head on the crown"
    ],
    [
     null,
     "button-head-screws-metric",
     "button-m3x8",
     3,
     "retainer screws into the crown"
    ],
    [
     null,
     "tube-piston-rods-5mm",
     "tube-rod-5x3.4x80",
     1,
     "piston to yoke, through the bushings"
    ],
    [
     null,
     "tri-clamp-rd-yokes",
     "rd-yoke-tube5",
     1,
     "on the tube rod's end"
    ],
    [
     null,
     "set-screws-metric",
     "set-m3x3",
     1,
     "tube yoke grub"
    ],
    [
     null,
     "connecting-rods-623",
     "conrod-80",
     1,
     "power"
    ],
    [
     null,
     "counterweighted-crank-discs",
     "cw-crank-disc-stroke20",
     1,
     "20 mm stroke, overhung on the shaft end"
    ],
    [
     null,
     "stirling-crankshafts",
     "crankshaft-5x80-dflat",
     1,
     "disc face to flywheel hub"
    ],
    [
     null,
     "shaft-spacers",
     "spacer-5mm-t5",
     1,
     "disc hub to the front bearing"
    ],
    [
     null,
     "shaft-spacers",
     "spacer-5mm-t1",
     1,
     ""
    ],
    [
     null,
     "ball-bearings-metric",
     "bearing-625",
     2,
     "in the tower"
    ],
    [
     null,
     "shaft-collars",
     "collar-5mm",
     1,
     "behind the tower"
    ],
    [
     null,
     "nut-pocket-flywheels",
     "flywheel-150-m10-b5",
     1,
     "on the shaft's far end"
    ],
    [
     null,
     "hex-nut-weights",
     "nut-m10",
     18,
     "one in each rim pocket"
    ],
    [
     null,
     "tri-clamp-displacer",
     "displacer-shell-2in-120",
     1,
     "Ø46 × 120, 0.75 radial gap, 20 stroke"
    ],
    [
     null,
     "tri-clamp-displacer",
     "displacer-cap-2in",
     1,
     "closes the shell, holds the rod"
    ],
    [
     null,
     "displacer-rods",
     "rod-3x200",
     1,
     "displacer rod: up through the piston's gland and tube rod"
    ],
    [
     null,
     "tri-clamp-rd-yokes",
     "rd-yoke-rod3",
     1,
     "on the displacer rod's top, stub pin toward +Y"
    ],
    [
     null,
     "tri-clamp-rd-link-webs",
     "rd-link-web-r10-90",
     1,
     "on crank pin 1, carries pin 2 a quarter turn away"
    ],
    [
     null,
     "connecting-rods-623",
     "conrod-40",
     1,
     "displacer"
    ],
    [
     null,
     "ball-bearings-metric",
     "bearing-623",
     4,
     "one in each con-rod eye"
    ],
    [
     null,
     "dowel-pins-metric",
     "dowel-3x12",
     2,
     "stub pins in the two yokes"
    ],
    [
     null,
     "dowel-pins-metric",
     "dowel-3x20",
     1,
     "crank pin 1: disc, power con-rod, link web"
    ],
    [
     null,
     "dowel-pins-metric",
     "dowel-3x16",
     1,
     "crank pin 2: link web, displacer con-rod"
    ],
    [
     null,
     "set-screws-metric",
     "set-m3x4",
     6,
     "grubs: displacer cap, rod yoke, piston, crank disc, collar, flywheel"
    ]
   ]
  }
 },
 "sheet_text": "Build list: Tri-clamp rolling-diaphragm beta, 2 in — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/list-tri-clamp-rd-beta/  (CC BY 4.0)\nBasis: Every part is a free STEP/STL on this site or a standard part with its own page; quantities are the full count, every screw, nut, pin, gasket and clamp.\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A torch-heated beta in two pieces of pressure vessel: a 2 in × 150 cup with the displacer, and the rolling-diaphragm power head straight on top of it, the displacer rod running up through the power piston.\n- Numbers: Numbers (with the optional finned cooler; cold end taken at 320 K): power swept 20.0 mL, displacer swept 33.2 mL, dead volume 38 mL (swept/dead 0.52); Schmidt work at 650 / 320 K and 1 bar mean 0.47 J per turn (1.57 pressure ratio, ±23 kPa); shaft power about 0.6–2.3 W at 300–600 rpm (0.25–0.5 of Schmidt).\n\nsubsystem  object  parts  qty  note\nNone  tri-clamp-rd-engine-frame  rd-frame-2in  1  base, wall, gussets\nNone  tri-clamp-torch-stand  torch-stand-40  1  on the base, post toward +Y; the heat source is a torch flame 40 mm under the cup\nNone  socket-head-cap-screws-metric  shcs-m4x10  2  torch stand to the base\nNone  set-screws-metric  set-m4x10  3  centre the torch head in the stand ring\nNone  tri-clamp-cups  cup-2in-150  1  the hot end and displacer cylinder in one piece: no joint near the flame\nNone  spool-hanger-collars  hanger-2in-tab  1  on the cup under the top clamp; bar to the wall\nNone  spool-hanger-collars  hanger-2in-plain  1  closes the hanger\nNone  socket-head-cap-screws-metric  shcs-m5x25  2  hanger bar through the wall\nNone  socket-head-cap-screws-metric  shcs-m4x20  2  hanger ears\nNone  hex-nuts-metric  nut-m4  2  hanger ears\nNone  tri-clamp-finned-cooler  cooler-half-2in-56  2  optional: clamp-on fin halves on the cup under the hanger (the cold end of the displacer cylinder); without them the engine runs with less power, or cool that part of the cup any way you like\nNone  socket-head-cap-screws-metric  shcs-m4x30  4  optional: cooler ears (only with the cooler)\nNone  hex-nuts-metric  nut-m4  4  optional: cooler ears (only with the cooler)\nNone  rolling-diaphragm-top-hat  rd-diaphragm-1.50-h1.50  1  1.50 in bore, 1.50 in high, flat flange: clamped in the joint in place of a gasket\nNone  tri-clamp-rd-power-head  rd-power-head-2in  1  standard 2 in clamp face, Ø38.10 cylinder, bushing seat, crank tower\nNone  tri-clamp-rd-power-head  rd-seat-ring-2in  1  in the head's face recess, behind the diaphragm flange\nNone  tri-clamp-clamps  clamp-half-2in  2  1 joint, two halves each\nNone  socket-head-cap-screws-metric  shcs-m5x30  2  clamp bolts\nNone  hex-nuts-metric  nut-m5  4  clamp nuts (2), hanger bar (2)\nNone  sleeve-bushings  bushing-5x8x12  2  back to back in the head's Ø8 seat: guide the tube rod\nNone  tri-clamp-rd-piston  rd-piston-2in  1  Ø33.27, never touches the bore\nNone  tri-clamp-rd-piston  rd-retainer-26-gland3  1  clamps the diaphragm head on the crown\nNone  button-head-screws-metric  button-m3x8  3  retainer screws into the crown\nNone  tube-piston-rods-5mm  tube-rod-5x3.4x80  1  piston to yoke, through the bushings\nNone  tri-clamp-rd-yokes  rd-yoke-tube5  1  on the tube rod's end\nNone  set-screws-metric  set-m3x3  1  tube yoke grub\nNone  connecting-rods-623  conrod-80  1  power\nNone  counterweighted-crank-discs  cw-crank-disc-stroke20  1  20 mm stroke, overhung on the shaft end\nNone  stirling-crankshafts  crankshaft-5x80-dflat  1  disc face to flywheel hub\nNone  shaft-spacers  spacer-5mm-t5  1  disc hub to the front bearing\nNone  shaft-spacers  spacer-5mm-t1  1  \nNone  ball-bearings-metric  bearing-625  2  in the tower\nNone  shaft-collars  collar-5mm  1  behind the tower\nNone  nut-pocket-flywheels  flywheel-150-m10-b5  1  on the shaft's far end\nNone  hex-nut-weights  nut-m10  18  one in each rim pocket\nNone  tri-clamp-displacer  displacer-shell-2in-120  1  Ø46 × 120, 0.75 radial gap, 20 stroke\nNone  tri-clamp-displacer  displacer-cap-2in  1  closes the shell, holds the rod\nNone  displacer-rods  rod-3x200  1  displacer rod: up through the piston's gland and tube rod\nNone  tri-clamp-rd-yokes  rd-yoke-rod3  1  on the displacer rod's top, stub pin toward +Y\nNone  tri-clamp-rd-link-webs  rd-link-web-r10-90  1  on crank pin 1, carries pin 2 a quarter turn away\nNone  connecting-rods-623  conrod-40  1  displacer\nNone  ball-bearings-metric  bearing-623  4  one in each con-rod eye\nNone  dowel-pins-metric  dowel-3x12  2  stub pins in the two yokes\nNone  dowel-pins-metric  dowel-3x20  1  crank pin 1: disc, power con-rod, link web\nNone  dowel-pins-metric  dowel-3x16  1  crank pin 2: link web, displacer con-rod\nNone  set-screws-metric  set-m3x4  6  grubs: displacer cap, rod yoke, piston, crank disc, collar, flywheel\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\nXem Studio scan: not planned; the official CAD above covers it.\nAPI: https://xemstudio.com/api/geometry?object=list-tri-clamp-rd-beta\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": "not-scanned",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "rolling-diaphragm-top-hat",
  "tri-clamp-rd-power-head",
  "tri-clamp-rd-piston",
  "tri-clamp-rd-yokes",
  "tri-clamp-rd-link-webs",
  "tri-clamp-rd-engine-frame",
  "tri-clamp-cups",
  "tri-clamp-finned-cooler",
  "list-beta-rhombic-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": [],
 "faq": [
  {
   "q": "What parts do I need for the rolling-diaphragm beta?",
   "a": "46 parts, every one a free STEP/STL on this site; see the table and the build order on this page."
  },
  {
   "q": "Why no piston fit?",
   "a": "The power piston is a rolling diaphragm: the piston is 2.41 mm clear of the bore all round and the diaphragm rolls between them."
  },
  {
   "q": "Where is the gasket at the top joint?",
   "a": "The diaphragm's flange is the gasket, with the seat ring behind it."
  },
  {
   "q": "Do I need the finned cooler?",
   "a": "No. It is an optional heat exchanger that clamps on the plain cup; without it the engine runs with less power. Any cooling of the top of the cup works, even a wet rag. The numbers above assume the cold end held near 320 K."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/list-tri-clamp-rd-beta/index.md"
}