{
 "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": "htd-water-tray-10in",
 "name": "Water tray for a 10 in cold cap (optional)",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Tri-clamp engine parts",
 "year": null,
 "question": "How do I cool the top of a big flat Stirling engine?",
 "tags": [
  "water tray",
  "cooler",
  "htd",
  "heat exchanger"
 ],
 "aliases": [
  "stirling water cooled top plate"
 ],
 "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/htd-water-tray-10in/",
 "sheet_txt": "https://xemstudio.com/objects/htd-water-tray-10in/sheet.txt",
 "sheet": {
  "basis": "Exact geometry",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A separate heat exchanger, optional: an open ring tray that sits on the cold cap's flat top round the 2 in ferrule and holds water. The cap takes about the cup wall's leak plus the engine's rejected heat (a few hundred watts at full fire), so the water warms and has to be topped up; ice water helps. The engine runs without it, hotter on the cold side."
  ],
  "table": {
   "columns": [
    "id_mm",
    "od_mm",
    "height_mm"
   ],
   "rows": [
    [
     118,
     190,
     40
    ]
   ]
  }
 },
 "sheet_text": "Water tray for a 10 in cold cap (optional) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/htd-water-tray-10in/  (CC BY 4.0)\nBasis: Exact geometry\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A separate heat exchanger, optional: an open ring tray that sits on the cold cap's flat top round the 2 in ferrule and holds water. The cap takes about the cup wall's leak plus the engine's rejected heat (a few hundred watts at full fire), so the water warms and has to be topped up; ice water helps. The engine runs without it, hotter on the cold side.\n\nid_mm  od_mm  height_mm\n118.0  190.0  40.0\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/htd-water-tray-10in/index.json\nAPI: https://xemstudio.com/api/geometry?object=htd-water-tray-10in\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": [
  "list-htd-10in",
  "htd-cold-caps-10in"
 ],
 "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": "floor",
   "exact": "Ø118–Ø190",
   "mates": "cold cap flat top (sits on it)",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "ID",
   "exact": "Ø118",
   "mates": "2 in ferrule, clamp and gauge boss (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": "Does the engine need the tray?",
   "a": "No, but the cold side runs hotter and the output drops without it."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "water-tray-10in",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/htd-water-tray-10in/water-tray-10in.step",
   "stl": "https://xemstudio.com/files/hardware/htd-water-tray-10in/water-tray-10in.stl",
   "note": "water tray (heat exchanger, optional): ring Ø118/Ø190 × 40, 2 walls and floor, sits on the cap's flat top"
  }
 ],
 "markdown": "https://xemstudio.com/objects/htd-water-tray-10in/index.md"
}