Library › Assembled engines ·

Free-piston Stirling generator, 2 in tri-clamp (pressurised, linear alternator)

A real free-piston Stirling generator in standard 2 in sanitary fittings: closed-end hot spool over a torch, annular screen regenerator, flexure leaves clamped in the joints, a magnet-carrying power piston in a bored spool with the alternator outside its wall, helium or air at up to 10 bar.

Ø48 piston ±5 mm, Ø39.4 displacer ±4.5 leading 68° · 45 Hz · helium 10 bar: 43 W electrical, 24 % of 180 W into the head · air 10 bar 28 W · 1 bar: 0.1 W helium, 0.1 W air · relief 15 bar g

Exact dimensions. Every part is drawn at true size with no printing tolerance; each part's page lists its mating features and the fit each joint needs, so open those by your process's clearance before making the parts.

Used in Long Earth Society builds. Thermoacoustic engine spool (aluminum) · Designing a displacer for a 3-foot free-piston Stirling engine · Designing a free-piston Stirling engine · Laser-cut linear flexure bearing

54 parts, every one a file here · all STL URLs · Markdown · tick lines as you go (saved in this browser)

Assembled engine

A pressurised free-piston Stirling generator in 2 in tri-clamp fittings: a closed-end hot spool over a torch in a split burner shroud, an annular screen regenerator round the displacer's liner, a water-jacketed cooler spool, flexure leaves clamped in the joints like gaskets, a 48 mm power piston carrying 40 magnets in a bored spool with the laminated stator and coil outside its wall, and the displacer's gas spring in the top spool under a four-port cap, hung on a 2020 stand; about 140 × 283 × 696 mm.

Assembly STEP (9.4 MB) · STL (22.7 MB) · 578 parts

Build order

1. Torch stand on the bench (post toward +Y), torch head in its ring. Rails, uprights, brackets; the rails clamped or screwed to the bench (the engine vibrates).
2. Hot spool S1 closed end down. Heater insert onto the liner's lower end; liner into S1; the 389 screen rings into the annulus up to the rim's underside.
3. Half gasket (bead down) on S1's face, the liner's rim on it, half gasket (bead up); S3 on top (cooler insert pressed in first); high-pressure clamp A.
4. Displacer: cap pressed into the shell; rod into the cap's socket; displacer down into the liner. Leaf B between half gaskets on S3's face over the cap's boss; collar on the rod onto the hub, grub.
5. Piston: 40 magnets into their pockets (S, N, N, S rows from the crown); top plate; tube rod. Coil (on its bobbin) over S4's flange and down to the magnets' height; S4 on joint B, clamp B; piston down S4 over the rod.
6. Stator packs round S4 at the coil, housing halves with 4 × M4 × 20; leads out through the housing's hole. Collar, half gasket, leaf C, half gasket, S5, collar; clamp C. Collar, leaf D (turned over) between half gaskets, collar; S6; clamp D.
7. Rod plug into the rod's top with the stinger; gas-spring piston on the stinger; gland and cylinder over it (3 × M3 × 16); cylinder pressed into S6's top. Type B gasket, port cap, clamp E; fill valve, gauge, relief valve, plug.
8. Two hangers stacked on S3 below the jacket (never clamp anything over S4's bored seal zone); shroud and fin sleeve on S1; jacket on S3; turn every clamp's bolt to the front (+Y). Charge slowly, connect the load and its series capacitor, then light the burner.

Agents: each row's object has /api/geometry?object=slug and the MCP tool get_free_files; the STL list above is every part.

JSON: /api/geometry?object=list-fpse-generator-2in