# Tri-clamp clamps (printable two-bolt), hot-joint gaskets and heat shields: every flange size, ½ to 4 in

> Can I print a tri-clamp clamp, and what gasket survives the hot end of a Stirling engine?

- Category: Stirling engines › Tri-clamp engine parts
- Kind: 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)
- Page: https://xemstudio.com/objects/tri-clamp-clamps/ · JSON: https://xemstudio.com/api/geometry?object=tri-clamp-clamps · Plain text: https://xemstudio.com/objects/tri-clamp-clamps/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

**Exact dimensions.** Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part.

## 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.
- The groove follows the ISO 2852 rim, so the clamp's working temperature is set by what it is made of; at a flame-side joint the clamp has to take that joint's temperature.
- Hot joints: the stock silicone/EPDM gasket is good to roughly 150–200 °C.
- Bore over the tube: tube OD + 2 mm (no contact, designed); M5 holes Ø5.5 (ISO 273); nut traps 8 AF exact (see Mating features). 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.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| clamp groove | ISO 2852 rim, 20° | two ferrule rims; walls touch after 0.4 mm, 0.6 mm squeeze | designed | clamp-half-* |
| nut traps | M5 hex, 8 AF | M5 nut | press | clamp-half-* |
| hot-gasket ring | C3 − 1 × bore | ferrule faces | designed | hot-gasket-* |
| clamp bore over the tube | tube OD + 2 | tube (no contact) | designed | clamp-half-* |
| bolt holes | Ø5.5 | M5 screw clearance (ISO 273) | designed | clamp-half-* |
| split / take-up | 1.0 per half, contact after 0.4 | the other half | designed | clamp-half-* |
| heat-shield bore | tube OD | tri-clamp tube | slide | heat-shield-* |

## Sizes

| size | tube_od_mm | rim_c3_mm | clamp_od_mm | clamp_width_mm | groove_throat_mm | contact_after_mm | bolts |
|---|---|---|---|---|---|---|---|
| 0.75 | 19.1 | 25.0 | 34.0 | 13.3 | 7.4 | 0.4 | 2 × M5 × 30 + nuts |
| 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 |
| 2.5 | 63.5 | 77.5 | 86.5 | 16.3 | 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 |
| 4 | 101.6 | 119.0 | 128.0 | 17.5 | 7.4 | 0.4 | 2 × M5 × 30 + nuts |

## Where the files are

- ISO: [ISO 2852:1993 Stainless steel clamp pipe couplings for the food industry](https://www.iso.org/standard/7873.html) — standard — ISO (verify at link)
- Long Earth Society: [Tri-clamp Stirling engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (18 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/tri-clamp-clamps/index.json

- clamp-half-0.75in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/clamp-half-0.75in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/clamp-half-0.75in.stl) — ½–¾ 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 through Ø5.5 holes, nuts in 8 AF hex traps; 13.3 mm wide
- hot-gasket-template-0.75in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-template-0.75in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-template-0.75in.stl) — 0.75 in flat hot-joint gasket
- heat-shield-0.75in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/heat-shield-0.75in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/heat-shield-0.75in.stl) — 0.75 in heat shield washer Ø50 × Ø19.05 bore (= tube OD): trace on sheet, slips over the tube between flame and clamp
- clamp-half-1.5in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/clamp-half-1.5in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/clamp-half-1.5in.stl) — 1–1½ 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 through Ø5.5 holes, nuts in 8 AF hex traps; 15.7 mm wide
- hot-gasket-template-1.5in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-template-1.5in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-template-1.5in.stl) — 1.5 in flat hot-joint gasket
- heat-shield-1.5in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/heat-shield-1.5in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/heat-shield-1.5in.stl) — 1.5 in heat shield washer Ø75.5 × Ø38.1 bore (= tube OD): trace on sheet, slips over the tube between flame and clamp
- clamp-half-2in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/clamp-half-2in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/clamp-half-2in.stl) — 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 through Ø5.5 holes, nuts in 8 AF hex traps; 16.0 mm wide
- hot-gasket-template-2in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-template-2in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-template-2in.stl) — 2 in flat hot-joint gasket
- heat-shield-2in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/heat-shield-2in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/heat-shield-2in.stl) — 2 in heat shield washer Ø89 × Ø50.8 bore (= tube OD): trace on sheet, slips over the tube between flame and clamp
- clamp-half-2.5in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/clamp-half-2.5in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/clamp-half-2.5in.stl) — 2.5 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 through Ø5.5 holes, nuts in 8 AF hex traps; 16.3 mm wide
- hot-gasket-template-2.5in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-template-2.5in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-template-2.5in.stl) — 2.5 in flat hot-joint gasket
- heat-shield-2.5in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/heat-shield-2.5in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/heat-shield-2.5in.stl) — 2.5 in heat shield washer Ø102.5 × Ø63.5 bore (= tube OD): trace on sheet, slips over the tube between flame and clamp
- clamp-half-3in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/clamp-half-3in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/clamp-half-3in.stl) — 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 through Ø5.5 holes, nuts in 8 AF hex traps; 16.5 mm wide
- hot-gasket-template-3in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-template-3in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-template-3in.stl) — 3 in flat hot-joint gasket
- heat-shield-3in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/heat-shield-3in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/heat-shield-3in.stl) — 3 in heat shield washer Ø116 × Ø76.2 bore (= tube OD): trace on sheet, slips over the tube between flame and clamp
- clamp-half-4in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/clamp-half-4in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/clamp-half-4in.stl) — 4 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 through Ø5.5 holes, nuts in 8 AF hex traps; 17.5 mm wide
- hot-gasket-template-4in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-template-4in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-template-4in.stl) — 4 in flat hot-joint gasket
- heat-shield-4in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/heat-shield-4in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/heat-shield-4in.stl) — 4 in heat shield washer Ø144 × Ø101.6 bore (= tube OD): trace on sheet, slips over the tube between flame and clamp

## How it fits

### Goes in or on
- [Tri-clamp (Tri-Clover) sanitary ferrule, 1/2 to 4 inch](https://xemstudio.com/objects/tri-clamp-ferrule/): groove fits the ISO 2852 rim and back cone
- [Tri-clamp spool (two ferrules on a tube), 1.5 and 2 inch](https://xemstudio.com/objects/tri-clamp-spool/): any spool joint

### Also needed
- [Tri-clamp end cap and gasket, 1.5 and 2 inch](https://xemstudio.com/objects/tri-clamp-end-cap/): Type B gasket for cold joints
- [Hex nuts, M2–M8 (ISO 4032)](https://xemstudio.com/objects/hex-nuts-metric/): M5 nuts in the traps
- [Socket head cap screws, M2–M8 (ISO 4762 / DIN 912)](https://xemstudio.com/objects/socket-head-cap-screws-metric/): M5 × 30
- [Regenerator and heat materials: stainless mesh counts, steel wool, scrubbers, mica, fiberglass, ceramic, firebrick](https://xemstudio.com/objects/regenerator-and-heat-materials/): mica / ceramic for the hot side

## 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. At a flame-side joint the clamp has to take that joint's temperature.

**What gasket for a hot tri-clamp joint?**

Use the flat hot-gasket ring (template here) in place of the Type B gasket on a hot joint, and the heat-shield washer between the flame and the clamp.

**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.

## Fits with

- [Tri-clamp (Tri-Clover) sanitary ferrule, 1/2 to 4 inch](https://xemstudio.com/objects/tri-clamp-ferrule/)
- [Tri-clamp spool (two ferrules on a tube), 1.5 and 2 inch](https://xemstudio.com/objects/tri-clamp-spool/)
- [Tri-clamp end cap and gasket, 1.5 and 2 inch](https://xemstudio.com/objects/tri-clamp-end-cap/)
- [Tri-clamp cups: closed-end spools (ferrule on a capped tube), 1.5, 2 and 3 in](https://xemstudio.com/objects/tri-clamp-cups/)
- [Hex nuts, M2–M8 (ISO 4032)](https://xemstudio.com/objects/hex-nuts-metric/)
- [Socket head cap screws, M2–M8 (ISO 4762 / DIN 912)](https://xemstudio.com/objects/socket-head-cap-screws-metric/)
- [Regenerator and heat materials: stainless mesh counts, steel wool, scrubbers, mica, fiberglass, ceramic, firebrick](https://xemstudio.com/objects/regenerator-and-heat-materials/)