{
 "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-cold-caps-10in",
 "name": "HTD cold caps: 10 in tri-clamp caps with a 2 in ferrule at the centre",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Tri-clamp engine parts",
 "year": null,
 "question": "What cap closes the cold side of a 10 inch tri-clamp HTD engine?",
 "tags": [
  "htd",
  "cold cap",
  "tri-clamp",
  "stirling",
  "npt boss"
 ],
 "aliases": [
  "10 inch tri clamp cap with ferrule",
  "tri clamp cap 2 inch boss",
  "stirling cold plate tri clamp"
 ],
 "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-cold-caps-10in/",
 "sheet_txt": "https://xemstudio.com/objects/htd-cold-caps-10in/sheet.txt",
 "sheet": {
  "basis": "Fabrication spec: 10 in end cap profile at 15.875 (5/8 in) instead of the standard 12.19, a 2 in L14AM7-type ferrule welded on at the centre, bosses machined; exact geometry",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Why thicker than a stock cap: at 6 bar gauge a stock 0.480 in cap sees 85 MPa and bows 0.35 mm; this 15.875 cap with its welded centre neck sees about 53 MPa and bows 0.16 mm, and it carries the welded ferrule, the guide boss and the NPT bosses.",
   "Main cap: the 2 in ferrule takes the bored power spool; inside it a Ø16 boss 20 tall carries the Ø6 displacer-rod guide (35.9 long through boss and plate); six Ø10 passages on r 16 let the gas between the chamber and the power cylinder; a 1/8 NPT boss at r 43 is the working-space gauge port.",
   "The flat top (inside Ø196.8, where the 20° back cone ends) carries the optional water tray."
  ],
  "table": {
   "columns": [
    "part",
    "thickness_mm",
    "centre",
    "ports"
   ],
   "rows": [
    [
     "cold-cap-10in-main",
     15.875,
     "2 in ferrule, Ø6 guide, 6 × Ø10",
     "1/8 NPT gauge"
    ]
   ]
  }
 },
 "sheet_text": "HTD cold caps: 10 in tri-clamp caps with a 2 in ferrule at the centre — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/htd-cold-caps-10in/  (CC BY 4.0)\nBasis: Fabrication spec: 10 in end cap profile at 15.875 (5/8 in) instead of the standard 12.19, a 2 in L14AM7-type ferrule welded on at the centre, bosses machined; exact geometry\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Why thicker than a stock cap: at 6 bar gauge a stock 0.480 in cap sees 85 MPa and bows 0.35 mm; this 15.875 cap with its welded centre neck sees about 53 MPa and bows 0.16 mm, and it carries the welded ferrule, the guide boss and the NPT bosses.\n- Main cap: the 2 in ferrule takes the bored power spool; inside it a Ø16 boss 20 tall carries the Ø6 displacer-rod guide (35.9 long through boss and plate); six Ø10 passages on r 16 let the gas between the chamber and the power cylinder; a 1/8 NPT boss at r 43 is the working-space gauge port.\n- The flat top (inside Ø196.8, where the 20° back cone ends) carries the optional water tray.\n\npart  thickness_mm  centre  ports\ncold-cap-10in-main  15.875  2 in ferrule, Ø6 guide, 6 × Ø10  1/8 NPT gauge\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Steel & O'Brien: Sanitary products catalog 2024: 16AMP end caps 10 / 12 in (A 0.480, B 10.570 / 12.570 in); L14AM7 ferrules 1.500 in; clamp ratings 13MHHM, 13MHP, 13ASME — PDF — publisher's catalogue; dimensions cited, nothing copied — https://www.steelobrien.com/wp-content/uploads/2024/03/Sanitary-2024-FINAL.pdf\n- McGraw-Hill: Young & Budynas, Roark's Formulas for Stress and Strain, 7th ed.: Table 8.1 (fixed–guided beam), Table 11.2 (circular plates under uniform pressure) — book — formulas are facts [verify license at link] — https://www.accessengineeringlibrary.com/content/book/9780071742474\n- ASME: ASME B1.20.1 Pipe Threads (NPT): 1/8-27 and 1/4-18, tap drills Ø8.6 / Ø11.1 as on this site's thread envelopes — standard — ASME; dimensions are facts [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/b1-20-1-pipe-threads-general-purpose-inch\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-cold-caps-10in/index.json\nAPI: https://xemstudio.com/api/geometry?object=htd-cold-caps-10in\n",
 "sources": [
  {
   "publisher": "Steel & O'Brien",
   "title": "Sanitary products catalog 2024: 16AMP end caps 10 / 12 in (A 0.480, B 10.570 / 12.570 in); L14AM7 ferrules 1.500 in; clamp ratings 13MHHM, 13MHP, 13ASME",
   "url": "https://www.steelobrien.com/wp-content/uploads/2024/03/Sanitary-2024-FINAL.pdf",
   "formats": [
    "PDF"
   ],
   "license": "publisher's catalogue; dimensions cited, nothing copied",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "McGraw-Hill",
   "title": "Young & Budynas, Roark's Formulas for Stress and Strain, 7th ed.: Table 8.1 (fixed–guided beam), Table 11.2 (circular plates under uniform pressure)",
   "url": "https://www.accessengineeringlibrary.com/content/book/9780071742474",
   "formats": [
    "book"
   ],
   "license": "formulas are facts",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "ASME",
   "title": "ASME B1.20.1 Pipe Threads (NPT): 1/8-27 and 1/4-18, tap drills Ø8.6 / Ø11.1 as on this site's thread envelopes",
   "url": "https://www.asme.org/codes-standards/find-codes-standards/b1-20-1-pipe-threads-general-purpose-inch",
   "formats": [
    "standard"
   ],
   "license": "ASME; dimensions are facts",
   "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": [
  "list-htd-10in",
  "htd-hot-cup-10in",
  "htd-bored-power-spool",
  "npt-thread-envelopes"
 ],
 "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": "face",
   "exact": "ISO 2852 10 in",
   "mates": "gasket-10in + 10 in clamp",
   "fit": "clamp",
   "files": "all"
  },
  {
   "feature": "2 in ferrule face",
   "exact": "ISO 2852 2 in",
   "mates": "tc-gasket-2in + 2 in clamp",
   "fit": "clamp",
   "files": "all"
  },
  {
   "feature": "rod guide",
   "exact": "Ø6 × 35.9 (plate + boss)",
   "mates": "Ø6 displacer rod",
   "fit": "run",
   "files": "cold-cap-10in-main"
  },
  {
   "feature": "gas passages",
   "exact": "6 × Ø10 on r 16",
   "mates": "gas (no contact)",
   "fit": "designed",
   "files": "cold-cap-10in-main"
  },
  {
   "feature": "gauge port",
   "exact": "1/8-27 NPT, tap drill Ø8.6 × 10",
   "mates": "1/8 NPT male",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "flat top",
   "exact": "inside Ø196.8",
   "mates": "water tray floor",
   "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 a stock 10 in cap?",
   "a": "It would hold the pressure, but the centre needs a welded 2 in ferrule and bosses; I make the plate 5/8 in so the welded centre and the ports keep the stress and bow low."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "cold-cap-10in-main",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/htd-cold-caps-10in/cold-cap-10in-main.step",
   "stl": "https://xemstudio.com/files/hardware/htd-cold-caps-10in/cold-cap-10in-main.stl",
   "note": "10 in cold cap 15.875 thick: 2 in L14AM7-type ferrule welded at the centre, Ø16 × 20 guide boss, Ø6 rod guide, six Ø10 passages on r 16, 1/8 NPT gauge boss at r 43"
  }
 ],
 "markdown": "https://xemstudio.com/objects/htd-cold-caps-10in/index.md"
}