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Tri-clamp clamps (printable two-bolt), hot-joint gaskets and heat shields: 1.5, 2 and 3 in
Can I print a tri-clamp clamp, and what gasket survives the hot end of a Stirling engine? · Hardware · basis: Groove derived from the ISO 2852 ferrule on this site: 2.85 mm rim, 20° back cone, C3 rim diameter, Type B gasket web 1.7 mm between the lands; two-bolt closure: groove contact after 0.4 mm of travel, 0.6 mm more before the halves meet (≈0.44 mm gasket squeeze)
Long Earth Society build part. The clamps and hot gaskets for every tri-clamp engine here. The engines
- sizes
- 3 in table
Notes
- The groove is the ferrule's own back cone mirrored: as the two M5 bolts pull the halves together, the 20° walls wedge the rims toward each other and squeeze the gasket. Each half has 1.0 mm to travel: the walls touch the rims after 0.4 mm and the last 0.6 mm squeezes the gasket about 0.44 mm (0.6 × tan 20° per rim) before the halves meet, so a closed gap means a seated joint.
- Printed clamps are for the cold side, mock-ups and low-pressure engines: PETG to ~70 °C, nylon/PA-CF to ~120 °C. On the flame side buy a stainless single-pin or two-bolt clamp for the size; the groove is the same, so the printed one tells you the fit.
- Hot joints: the stock silicone/EPDM gasket is good to roughly 150–200 °C. At a flame-side joint use a flat gasket cut from 0.5 mm graphite sheet or mica from the template, and slide a mica heat-shield washer over the tube between the flame and the clamp.
- Print each half flat (clamp plane on the bed), 4 walls, 40 % infill; drop M5 nuts into the traps; M5 × 30 screws through both lugs. Tighten evenly until the gap between the halves is just closed on both sides.
- LES: the clamps and hot gaskets every tri-clamp engine on this shelf needs.
Sizes
| size | tube_od_mm | rim_c3_mm | clamp_od_mm | clamp_width_mm | groove_throat_mm | contact_after_mm | bolts |
|---|---|---|---|---|---|---|---|
| 1.5 | 38.1 | 50.5 | 59.5 | 15.7 | 7.4 | 0.4 | 2 × M5 × 30 + nuts |
| 2 | 50.8 | 64.0 | 73.0 | 16.0 | 7.4 | 0.4 | 2 × M5 × 30 + nuts |
| 3 | 76.2 | 91.0 | 100.0 | 16.5 | 7.4 | 0.4 | 2 × M5 × 30 + nuts |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| ISO | ISO 2852:1993 Stainless steel clamp pipe couplings for the food industry | standard | ISO verify |
| Long Earth Society | Tri-clamp Stirling engine builds | web, video | LES site |
Free files
★ Free files 9 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json
| clamp-half-1.5in | 1.5 in two-bolt clamp half (print two): 20° groove for the ISO 2852 rims, contact after 0.4 mm, 0.6 mm squeeze before the halves meet, 2 × M5 × 30 with nuts in hex traps; 15.7 mm wide | STEP · STL |
| hot-gasket-template-1.5in | 1.5 in flat hot-joint gasket: Ø49.5 × Ø34.8 ring to trace on 0.5 mm graphite or mica sheet (replaces the silicone/EPDM gasket on a flame-side joint) | STEP · STL |
| heat-shield-1.5in | 1.5 in heat shield washer Ø76: trace on mica, slips over the tube between flame and clamp | STEP · STL |
| clamp-half-2in | 2 in two-bolt clamp half (print two): 20° groove for the ISO 2852 rims, contact after 0.4 mm, 0.6 mm squeeze before the halves meet, 2 × M5 × 30 with nuts in hex traps; 16.0 mm wide | STEP · STL |
| hot-gasket-template-2in | 2 in flat hot-joint gasket: Ø63 × Ø47.5 ring to trace on 0.5 mm graphite or mica sheet (replaces the silicone/EPDM gasket on a flame-side joint) | STEP · STL |
| heat-shield-2in | 2 in heat shield washer Ø89: trace on mica, slips over the tube between flame and clamp | STEP · STL |
| clamp-half-3in | 3 in two-bolt clamp half (print two): 20° groove for the ISO 2852 rims, contact after 0.4 mm, 0.6 mm squeeze before the halves meet, 2 × M5 × 30 with nuts in hex traps; 16.5 mm wide | STEP · STL |
| hot-gasket-template-3in | 3 in flat hot-joint gasket: Ø90 × Ø72.9 ring to trace on 0.5 mm graphite or mica sheet (replaces the silicone/EPDM gasket on a flame-side joint) | STEP · STL |
| heat-shield-3in | 3 in heat shield washer Ø116: trace on mica, slips over the tube between flame and clamp | STEP · STL |
Plain text: sheet.txt · JSON: /api/geometry?object=tri-clamp-clamps
How it fits
Goes in or on
Tri-clamp sanitary ferrule, 1/2 to 4 inchgroove fits the ISO 2852 rim and back cone
Tri-clamp spool, 1.5 and 2 inchany spool jointAlso needed
Tri-clamp end cap and gasket, 1.5 and 2 inchType B gasket for cold joints
Hex nuts, M2–M8M5 nuts in the traps
Socket head cap screws, M2–M8M5 × 30
Regenerator and heat materialsmica / ceramic for the hot sideIn these build lists
Gamma Stirling, 2 in tri-clampThe Long Earth Society engine: hot spool, shell displacer, graphite or syringe p…Thermoacoustic standing-wave engine, 2 in spoolsNo pistons: a printed stack in a λ/4 tube of spools; a speaker turns the sound i…Beta Stirling, rhombic drive, 2 in tri-clampDisplacer and piston in one bore, two counter-rotating gears: the balanced one.Free-piston Stirling, 2 in tri-clampNo crank: displacer rod through the piston, both hung on spiral flexure stacks; …You might also need
Questions
Can you 3D print a tri-clamp clamp?
Yes for cold joints and low pressure: print two halves of the two-bolt clamp for your size, M5 nuts in the traps, M5 × 30 screws. Its 20° groove mirrors the ferrule rims, so tightening pulls the faces together. Use stainless at the flame.
What gasket for a hot tri-clamp joint?
Flat 0.5 mm graphite or mica cut from the hot-gasket template; silicone and EPDM gaskets fail somewhere around 150–200 °C.
How tight should a tri-clamp clamp be?
Snug the bolts evenly until the two halves just meet on both sides; the 20° groove has already squeezed the gasket by then.