# Build list: Beta Stirling, rhombic drive, 2 in tri-clamp

> What parts do I need to build a Beta Stirling, rhombic drive, 2 in tri-clamp?

- Category: Stirling engines › Guide
- Kind: List / guide
- Basis: Every printed part is a free file on this site; bought items named with quantities
- Page: https://xemstudio.com/objects/list-beta-rhombic-2in/ · JSON: https://xemstudio.com/api/geometry?object=list-beta-rhombic-2in · Plain text: https://xemstudio.com/objects/list-beta-rhombic-2in/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

## Notes

- Displacer and piston in one bore, two counter-rotating gears: the balanced one.
- Numbers: Ø46 × 90 regenerative displacer · Ø40 lapped piston · 16 mm strokes · phase ~90° from c 32 / e 8 / L 40

## Sizes

| subsystem | object | parts | qty | print_or_buy | note |
|---|---|---|---|---|---|
| Hot end | tri-clamp-end-cap | tc-cap-2in-flat | 1 | print | flame side; stainless for a burner |
| Cylinder | tri-clamp-spool | tc-spool-2in-6in | 1 | buy | stainless, 16 ga, 47.5 bore |
| Joints | tri-clamp-end-cap | tc-gasket-2in | 2 | buy | ISO 2852 Type B gaskets on the cold joints |
| Clamps | tri-clamp-clamps | clamp-half-2in | 4 | print | two halves per joint; stainless clamp at the flame side |
| Hot joint | tri-clamp-clamps | hot-gasket-template-2in, heat-shield-2in | 1 | print | trace on 0.5 mm graphite / mica sheet for the flame-side joint |
| Displacer | tri-clamp-displacers-and-heads | displacer-regenerative-2in-90, displacer-regenerative-cap-2in | 1 | print | slots packed with #100 mesh; Ø3 rod on the cap's M3 grub |
| Power piston | tri-clamp-power-pistons | piston-2in-f020-rod, lapping-handle-2in | 1 | print | lap to fit in the spool; 3 × 5 × 6 bushing in the crown |
| Piston plug | tri-clamp-free-piston-kit | fp-piston-plug-2in | 1 | print | drops into the skirt; carries the 5 mm tube rod |
| Wrist dowels | dowel-pins-metric | dowel-3x16 | 2 | buy | through bosses and plug legs |
| Rod bushing | bearing-housings-and-rod-supports | bushing-3x5x6 | 1 | buy | dry: graphite-bronze, or sintered bronze degreased in acetone; no oil |
| Rods | brass-tube-ks | brass-5mm | 1 | buy | 5 mm K&S tube = piston rod into the plug (printed tube-rod for a mock-up) |
| Displacer rod | stirling-shafts-and-rods | rod-3x200 | 1 | print | cut to length; steel Ø3 for running |
| Frame head | stirling-linkage-fittings | rhombic-frame-head-2in | 1 | print | clamps on the spool's open ferrule; gear axes 70 mm above the face |
| Stand | spool-hanger-collars | hanger-2in-tab, hanger-2in-plain | 1 | print | clamps the cold half; bolts to a 2020 crossbar so the hot end hangs over the flame |
| Frame rails | t-slot-extrusions | 2020-100 | 3 | buy | two uprights + crossbar, cut to suit the flame height; M5 T-nuts |
| Drive | rhombic-drive-kit | crank-gear-30t-e8-left, crank-gear-30t-e8-right, link-40-1, link-40-2, link-40-3, link-40-4, yoke-upper-displacer, yoke-lower-piston, gear-frame-plate-c32 | 1 | print | print two frame plates; gears meshed 180° apart |
| Pins | dowel-pins-metric | dowel-3x12 | 6 | buy | 2 crank pins + 4 link pivots |
| Bearings | ball-bearings-metric | bearing-625 | 4 | buy | in the frame plates |
| Shafts | stirling-shafts-and-rods | crankshaft-5x80-dflat, crankshaft-5x120-dflat | 1 | print | gear shafts; the 120 carries the flywheel |
| Flywheel | nut-weighted-flywheels | flywheel-120-m10-b5 | 1 | print | Ø5 hub, no adapter; 12 M10 nuts |
| Fasteners | socket-head-cap-screws-metric | shcs-m3x10 | 4 | buy | plates to the frame head uprights |
| Heat | tea-light-candles | tea-light-maxi-58x24 | 1 | buy |  |

## Where the files are

- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Build order

1. Print the calibration coupons; set slicer offsets.
2. Print displacer + cap, piston (f020-rod), plug, lapping handle, frame head, rhombic gears, links, yokes, two plates, flywheel, adapter.
3. Lap the piston in the spool until it sinks slowly with the end open; press the bushing into its crown.
4. Plug into the skirt, dowels through; 5 mm tube into the plug socket (CA).
5. Displacer on its Ø3 rod; rod through the piston bushing and up the tube; displacer + piston into the spool.
6. Hot cap and gasket on the bottom; frame head and gasket on top; clamp both.
7. 625s in the plates; plates on the frame head uprights; gears on Ø5 shafts, meshed 180° apart.
8. Links to the gear pins; upper yoke on the Ø3 rod, lower yoke on the tube; set both at mid-stroke and lock the grubs.
9. Flywheel on the adapter; heat the bottom; turn to start.

All printed STLs: https://xemstudio.com/objects/list-beta-rhombic-2in/stl-list.txt

## Questions

**What parts do I need to build a Beta Stirling, rhombic drive, 2 in tri-clamp?**

25 printed parts (all free here) and 10 bought items; see the table and build order on this page.

**How do I download every STL for this build at once?**

The stl-list.txt on this page lists every printed part's STL URL; paste it into a download script or your slicer's import.

## Fits with

- [Tri-clamp end cap and gasket, 1.5 and 2 inch](https://xemstudio.com/objects/tri-clamp-end-cap/)
- [Tri-clamp spool (two ferrules on a tube), 1.5 and 2 inch](https://xemstudio.com/objects/tri-clamp-spool/)
- [Tri-clamp clamps (printable two-bolt), hot-joint gaskets and heat shields: 1.5, 2 and 3 in](https://xemstudio.com/objects/tri-clamp-clamps/)
- [Tri-clamp displacers and engine heads: 1.5, 2 and 3 in spools](https://xemstudio.com/objects/tri-clamp-displacers-and-heads/)
- [Tri-clamp power pistons and crank linkage: full-bore ring-less pistons, con-rods, crank webs and a clamp-on crank frame for 1.5, 2 and 3 in spools](https://xemstudio.com/objects/tri-clamp-power-pistons/)
- [Tri-clamp free-piston kit: flexure head, stack ring, hub collars and piston plug for 1.5, 2 and 3 in spools](https://xemstudio.com/objects/tri-clamp-free-piston-kit/)
- [Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)](https://xemstudio.com/objects/dowel-pins-metric/)
- [Bearing housings and linear supports: KP08, KFL08, SK8, SC8UU, V-wheels, sleeve bushings](https://xemstudio.com/objects/bearing-housings-and-rod-supports/)
- [Hobby brass tube (K&S), 1/16–21/32 in and 1–12 mm, telescoping](https://xemstudio.com/objects/brass-tube-ks/)
- [Stirling shafts and rods: Ø3 rods, Ø5 / Ø8 D-flat crankshafts, Ø5 tube rods, Ø3 pins, thrust spacers](https://xemstudio.com/objects/stirling-shafts-and-rods/)
- [Stirling linkage fittings: rod clevises, shaft adapter, 625 crank stands, Ø3 crank discs, rhombic frame heads](https://xemstudio.com/objects/stirling-linkage-fittings/)
- [Spool hanger collars: clamp a tri-clamp spool to 2020 extrusion over the flame (1.5, 2, 3 in)](https://xemstudio.com/objects/spool-hanger-collars/)