{
 "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": "ltd-top-plate",
 "name": "LTD Stirling top plate with syringe socket, Ø120 and Ø170",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Can & LTD engines",
 "year": null,
 "question": "What are the dimensions of the top plate of a coffee-cup (LTD) Stirling engine?",
 "tags": [
  "ltd",
  "low temperature differential",
  "coffee cup",
  "top plate",
  "syringe",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "coffee cup stirling top plate",
  "ltd stirling plate dimensions",
  "ltd stirling syringe mount",
  "low temperature stirling top plate stl"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 2,
 "url": "https://xemstudio.com/objects/ltd-top-plate/",
 "sheet_txt": "https://xemstudio.com/objects/ltd-top-plate/sheet.txt",
 "sheet": {
  "basis": "Senft LTD gamma layout, sized in the assembled Ø100 engine on this site; syringe socket at the 10 mL barrel OD Ø15.9; rod bore at the 2 mm rod; M3 clearance Ø3.4 (ISO 273), M3 tap drill Ø2.5",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "The cold plate of the LTD engine and its power cylinder mount. Ø120 (for the 100 chamber) or Ø170 (for the 150 chamber), 3 thick, with 6 × Ø3.4 on a Ø112 / Ø162 circle (at 30°, 90°, …) matching the chamber ring.",
   "At x −5 a Ø20 boss, 13 tall with the plate, has a Ø2 bore straight through for the 2 mm displacer rod (fit: run); the bore is the rod guide.",
   "At x 40 (45 from the rod guide, so the two con-rods can sit at the two ends of the crankshaft) a Ø21.9 boss rises to 20 mm with a Ø15.9 socket from 8 to 20 for a 10 mL syringe barrel (fit: socket) and a Ø10 port under it into the chamber: the barrel's closed end sits on the socket floor and its Luer tip ends flush with the plate's underside.",
   "Four Ø9 × 4 pads at (7.5, ±27) and (27.5, ±27) carry the two crank stands, each with an M3 tapped hole (Ø2.5) 6 deep."
  ],
  "table": {
   "columns": [
    "file",
    "plate",
    "screw circle",
    "rod guide",
    "syringe socket",
    "height"
   ],
   "rows": [
    [
     "ltd-100-top-plate-syringe",
     "Ø120 × 3",
     112,
     "Ø2 × 13 at x −5",
     "Ø15.9 × 12 at x 40",
     20
    ],
    [
     "ltd-150-top-plate-syringe",
     "Ø170 × 3",
     162,
     "Ø2 × 13 at x −5",
     "Ø15.9 × 12 at x 40",
     20
    ]
   ]
  }
 },
 "sheet_text": "LTD Stirling top plate with syringe socket, Ø120 and Ø170 — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/ltd-top-plate/  (CC BY 4.0)\nBasis: Senft LTD gamma layout, sized in the assembled Ø100 engine on this site; syringe socket at the 10 mL barrel OD Ø15.9; rod bore at the 2 mm rod; M3 clearance Ø3.4 (ISO 273), M3 tap drill Ø2.5\nCatalog version: 2026-10-20\n\nSizes: see table below\n- The cold plate of the LTD engine and its power cylinder mount. Ø120 (for the 100 chamber) or Ø170 (for the 150 chamber), 3 thick, with 6 × Ø3.4 on a Ø112 / Ø162 circle (at 30°, 90°, …) matching the chamber ring.\n- At x −5 a Ø20 boss, 13 tall with the plate, has a Ø2 bore straight through for the 2 mm displacer rod (fit: run); the bore is the rod guide.\n- At x 40 (45 from the rod guide, so the two con-rods can sit at the two ends of the crankshaft) a Ø21.9 boss rises to 20 mm with a Ø15.9 socket from 8 to 20 for a 10 mL syringe barrel (fit: socket) and a Ø10 port under it into the chamber: the barrel's closed end sits on the socket floor and its Luer tip ends flush with the plate's underside.\n- Four Ø9 × 4 pads at (7.5, ±27) and (27.5, ±27) carry the two crank stands, each with an M3 tapped hole (Ø2.5) 6 deep.\n\nfile  plate  screw circle  rod guide  syringe socket  height\nltd-100-top-plate-syringe  Ø120 × 3  112  Ø2 × 13 at x −5  Ø15.9 × 12 at x 40  20\nltd-150-top-plate-syringe  Ø170 × 3  162  Ø2 × 13 at x −5  Ø15.9 × 12 at x 40  20\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Stirling engine — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Stirling_engine\n- James R. Senft: An Introduction to Low Temperature Differential Stirling Engines — book — Moriya Press [verify license at link] — https://www.stirlingengine.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, 2 parts): https://xemstudio.com/files/hardware/ltd-top-plate/index.json\nAPI: https://xemstudio.com/api/geometry?object=ltd-top-plate\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Stirling engine",
   "url": "https://en.wikipedia.org/wiki/Stirling_engine",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "James R. Senft",
   "title": "An Introduction to Low Temperature Differential Stirling Engines",
   "url": "https://www.stirlingengine.com/",
   "formats": [
    "book"
   ],
   "license": "Moriya Press",
   "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": [
  "ltd-chamber-ring",
  "ltd-bottom-plate",
  "ltd-displacer",
  "ltd-crank-stand",
  "plastic-syringes",
  "list-ltd-coffee-cup"
 ],
 "fits": [
  {
   "role": "Parts that fit it",
   "items": [
    {
     "slug": "coat-hanger-and-paper-clip-wire",
     "why": "2 mm rod through the Ø2 bore in the top plate (run)"
    },
    {
     "slug": "ltd-crank-stand",
     "why": "2 × M3 down onto the top plate"
    },
    {
     "slug": "displacer-rods",
     "why": "Ø2 rod in the top plate's Ø2 bore"
    }
   ]
  },
  {
   "role": "Goes in or on",
   "items": [
    {
     "slug": "ltd-chamber-ring",
     "why": "6 × M3 on the Ø112 / Ø162 circle"
    }
   ]
  },
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "ltd-displacer",
     "why": "the displacer's 2 mm rod runs in the Ø2 bore"
    },
    {
     "slug": "plastic-syringes",
     "why": "10 mL barrel in the Ø15.9 socket"
    },
    {
     "slug": "syringe-pistons",
     "why": "power piston in that barrel"
    }
   ]
  },
  {
   "role": "Also needed",
   "items": [
    {
     "slug": "brass-tube-ks",
     "why": "2 mm rod"
    }
   ]
  }
 ],
 "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": "syringe socket",
   "exact": "Ø15.9",
   "mates": "10 mL syringe barrel",
   "fit": "socket",
   "files": "ltd-100-top"
  },
  {
   "feature": "syringe socket",
   "exact": "Ø15.9",
   "mates": "10 mL syringe barrel",
   "fit": "socket",
   "files": "ltd-150-top"
  },
  {
   "feature": "plate screw holes",
   "exact": "Ø3.4",
   "mates": "M3 screw clearance (ISO 273)",
   "fit": "designed",
   "files": "ltd-100-top"
  },
  {
   "feature": "plate screw holes",
   "exact": "Ø3.4",
   "mates": "M3 screw clearance (ISO 273)",
   "fit": "designed",
   "files": "ltd-150-top"
  },
  {
   "feature": "stand pad holes",
   "exact": "Ø2.5 × 6",
   "mates": "M3 tap drill",
   "fit": "designed",
   "files": "ltd-100-top"
  },
  {
   "feature": "stand pad holes",
   "exact": "Ø2.5 × 6",
   "mates": "M3 tap drill",
   "fit": "designed",
   "files": "ltd-150-top"
  },
  {
   "feature": "syringe port under the socket",
   "exact": "Ø10",
   "mates": "syringe tip (no contact)",
   "fit": "designed",
   "files": "ltd-100-top"
  },
  {
   "feature": "syringe port under the socket",
   "exact": "Ø10",
   "mates": "syringe tip (no contact)",
   "fit": "designed",
   "files": "ltd-150-top"
  },
  {
   "feature": "rod-guide bore",
   "exact": "Ø2 × 13",
   "mates": "2 mm displacer rod",
   "fit": "run",
   "files": "ltd-100-top-plate-"
  },
  {
   "feature": "rod-guide bore",
   "exact": "Ø2 × 13",
   "mates": "2 mm displacer rod",
   "fit": "run",
   "files": "ltd-150-top-plate-"
  }
 ],
 "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": "How does the displacer rod pass through an LTD top plate?",
   "a": "Through a Ø2 bore straight through the plate and its Ø20 centre boss, 13 long, drawn at the 2 mm rod (fit: run)."
  },
  {
   "q": "What syringe fits the LTD top plate?",
   "a": "A 10 mL barrel (Ø15.9 OD) in the 12 mm deep socket; its Luer tip sits in the Ø10 port below and ends flush with the plate's underside."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "ltd-100-top-plate-syringe",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/ltd-coffee-cup-engine-kit/ltd-100-top-plate-syringe.step",
   "stl": "https://xemstudio.com/files/hardware/ltd-coffee-cup-engine-kit/ltd-100-top-plate-syringe.stl",
   "note": "top plate Ø120 × 3: rod guide boss at x -5 (Ø2 bore, 13 long through plate and Ø20 boss), 10 mL syringe socket at x 40 (Ø15.9 from 8 to 20 above the underside, Ø10 port below so the Luer tip ends flush), 4 stand pads Ø9 × 4 with M3 tapped holes 6 deep, 6 × Ø3.4 on a Ø112 circle"
  },
  {
   "file": "ltd-150-top-plate-syringe",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/ltd-coffee-cup-engine-kit/ltd-150-top-plate-syringe.step",
   "stl": "https://xemstudio.com/files/hardware/ltd-coffee-cup-engine-kit/ltd-150-top-plate-syringe.stl",
   "note": "top plate Ø170 × 3: rod guide boss at x -5 (Ø2 bore, 13 long through plate and Ø20 boss), 10 mL syringe socket at x 40 (Ø15.9 from 8 to 20 above the underside, Ø10 port below so the Luer tip ends flush), 4 stand pads Ø9 × 4 with M3 tapped holes 6 deep, 6 × Ø3.4 on a Ø162 circle"
  }
 ],
 "markdown": "https://xemstudio.com/objects/ltd-top-plate/index.md"
}