# Tri-clamp spools to a custom length (fabrication spec): 2 in × 340.7 and 310.7 mm, ¾ in × 146.7 and 80.4 mm

> How do I order a tri-clamp spool in a length that isn't 3, 6 or 12 inches?

- Category: Hardware › Sanitary clamp fittings
- Kind: Hardware
- Basis: ASME BPE tube (2 in: Ø50.8 × 1.65; ¾ in: Ø19.05 × 1.65) and ISO 2852 ferrule faces exactly as the standard spools on this site (gen_sanitary.spool); lengths from the engine layouts in tools/gen_ta_power.py
- Page: https://xemstudio.com/objects/tri-clamp-custom-length-spools/ · JSON: https://xemstudio.com/api/geometry?object=tri-clamp-custom-length-spools · Plain text: https://xemstudio.com/objects/tri-clamp-custom-length-spools/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**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

- Plain spools: standard tube with a standard ferrule on each end, nothing else, cut to the stated face-to-face length. Any sanitary fabricator makes them from this drawing; a spool is the cheapest custom tri-clamp part there is.
- 2 in × 340.7: the core of each unit of the double-acting ring engine (two ambient exchangers, 100 mm regenerator, hot exchanger, 180 mm buffer tube, two 8.4 spacers between the gasket lips). 2 in × 310.7: the twin-piston engine's core.
- ¾ in × 146.7 and × 80.4: the riser pieces of each engine's ¾ in feedback line, between the instrument tee and cross.
- Fits: the faces are clamp faces; the 2 in bore Ø47.5 takes the exchanger inserts, screens and liners as a slide fit (Mating features).

## 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 |
|---|---|---|---|---|
| faces | ISO 2852 (2 in: land Ø56.5–Ø64; ¾ in: 25.0 flange), rim 2.85, 1.6 recess, 20° back | standard clamp + Type B gasket | clamp | all |
| 2 in bore | Ø47.5 × face to face | exchanger inserts (press), screen discs, spacers and liner (slide) | slide | spool-2in-* |
| ¾ in bore | Ø15.75 | gas passage (no contact) | designed | spool-0.75in-* |

## Sizes

| file | size_in | face_to_face_mm | tube_mm | use |
|---|---|---|---|---|
| spool-2in-340.7mm | 2 | 340.7 | 50.8 × 1.65 | ring core |
| spool-2in-310.7mm | 2 | 310.7 | 50.8 × 1.65 | twin core |
| spool-0.75in-146.7mm | 0.75 | 146.7 | 19.05 × 1.65 | ring riser |
| spool-0.75in-80.4mm | 0.75 | 80.4 | 19.05 × 1.65 | twin riser |

## Where the files are

- ASME: [BPE Bioprocessing Equipment (clamp fitting dimensions, tube OD and wall)](https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment) — standard — ASME; dimensions are facts (verify at link)
- ISO (via iTeh sample): [ISO 2852 clamp liners: face profile and flange / groove diameters](https://cdn.standards.iteh.ai/samples/7850/eb49c396488d408c8ced3e2961d76cf3/ISO-2852-1974.pdf) — PDF — standard excerpt; dimensions are facts
- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (4 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/tri-clamp-custom-length-spools/index.json

- spool-2in-340.7mm: [STEP](https://xemstudio.com/files/hardware/tri-clamp-custom-length-spools/spool-2in-340.7mm.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-custom-length-spools/spool-2in-340.7mm.stl) — 2 in spool, 340.7 mm face to face, 1.65 wall, ISO 2852 ferrules both ends: the ring engine's core
- spool-2in-310.7mm: [STEP](https://xemstudio.com/files/hardware/tri-clamp-custom-length-spools/spool-2in-310.7mm.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-custom-length-spools/spool-2in-310.7mm.stl) — 2 in spool, 310.7 mm face to face: the twin-piston engine's core
- spool-0.75in-146.7mm: [STEP](https://xemstudio.com/files/hardware/tri-clamp-custom-length-spools/spool-0.75in-146.7mm.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-custom-length-spools/spool-0.75in-146.7mm.stl) — ¾ in spool, 146.7 mm face to face (25.0 flange): ring-engine riser
- spool-0.75in-80.4mm: [STEP](https://xemstudio.com/files/hardware/tri-clamp-custom-length-spools/spool-0.75in-80.4mm.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-custom-length-spools/spool-0.75in-80.4mm.stl) — ¾ in spool, 80.4 mm face to face: twin-engine riser

## Questions

**Can I order a spool in any length?**

Yes: a spool is tube and two ferrules, so a sanitary fabricator cuts the tube to the face-to-face length you give.

**Why these lengths?**

Each is the sum of the parts that stack inside it between the two gasket lips (2 in) or what fills a riser exactly (¾ in).

## Fits with

- [Tri-clamp spool (two ferrules on a tube), 1.5 and 2 inch](https://xemstudio.com/objects/tri-clamp-spool/)
- [Sanitary clamp end caps (16AMP): ½ to 4 in](https://xemstudio.com/objects/sanitary-clamp-end-caps/)
- [Tri-clamp honed cylinder spool: 2 in × 6 in, bore finished Ø48.00](https://xemstudio.com/objects/tri-clamp-honed-cylinder-spool/)
- [Build list: Thermoacoustic-Stirling ring generator, three 2 in units, pressurised](https://xemstudio.com/objects/list-ta-ring-3x2in/)
- [Build list: Thermoacoustic-Stirling engine with twin free-piston alternators, 2 in, pressurised](https://xemstudio.com/objects/list-ta-twin-piston-2in/)