Xem Studiomeasured geometryGamma Stirling, 2 in tri-clamp
The Long Earth Society engine: hot spool, shell displacer, graphite or syringe piston, counterweighted crank, Ø100 flywheel.
Ø46 × 90 displacer at 20 mm stroke · Ø20 piston at 12 mm · ratio ~9 · 200–500 rpm on a tea light · 0.1–0.5 W
30 printed parts · 10 bought lines · all printed STL URLs · Markdown · tick lines as you go (saved in this browser)
| subsystem | object | parts | qty | note | ||
|---|---|---|---|---|---|---|
| Hot end | Tri-clamp end cap and gasket | tc-cap-2in-flat STEP · STL | 1 | flame side | ||
| Cylinder | Tri-clamp spool (two ferrules on a tube) | tc-spool-2in-6in STEP · STL | 1 | buy | buy the stainless spool; print to check | |
| Joints | Tri-clamp end cap and gasket | tc-gasket-2in STEP · STL | 2 | buy | ISO 2852 Type B gaskets on the cold joints | |
| Clamps | Tri-clamp clamps (printable two-bolt) | clamp-half-2in STEP · STL | 4 | two halves per joint; stainless clamp at the flame side | ||
| Hot joint | Tri-clamp clamps (printable two-bolt) | hot-gasket-template-2in STEP · STL heat-shield-2in STEP · STL | 1 | trace on 0.5 mm graphite / mica sheet for the flame-side joint | ||
| Displacer | Tri-clamp displacers and engine heads | displacer-shell-2in-90 STEP · STL displacer-cap-2in STEP · STL | 1 | 0.75 mm gap, 20 mm stroke | ||
| Regenerator | Regenerator and heat materials | regenerator-cage-47-5x40 STEP · STL | 1 | pack with #100 stainless mesh | ||
| Displacer rod | Shafts | shaft-3x100 STEP · STL | 1 | buy | Ø3 precision rod | |
| Rod guide | Hobby brass tube (K&S) | brass-3-32in STEP · STL | 1 | buy | 3/32 in K&S brass, press in the head | |
| Cold head | Tri-clamp displacers and engine heads | head-displacer-2in STEP · STL | 1 | guide bore + 4 mm barb; or head-crank-2in | ||
| Transfer | Silicone and PU tube | silicone-tube-4x6-50 STEP · STL barb-4mm STEP · STL | 1 | keep under 30 mm | ||
| Power cylinder | Power cylinder liners | liner-20x45-flanged STEP · STL piston-20x18-blank STEP · STL | 1 | lap to fit, or graphite piston in a Ø20 glass tube, or syringe-10ml | ||
| Crosshead | Power cylinder liners | crosshead-8mm-rod3 STEP · STL crosshead-guide-8mm STEP · STL wrist-pin-3x16 STEP · STL | 1 | recommended with a lapped piston | ||
| Base plate | Gamma frame | base-plate-2in STEP · STL | 1 | 4 × M5 to 2020 or a board | ||
| Crank stands | Stirling linkage fittings | crank-stand-625-h60 STEP · STL | 2 | 625 pockets for the Ø5 crankshaft; slotted feet match the base plate | ||
| Bearings | Ball bearings | bearing-623 STEP · STL bearing-625 STEP · STL | 6 | buy | 4 × 623 in the con-rods, 2 × 625 on the shaft | |
| Crankshaft | Shafts | shaft-5x200 STEP · STL | 1 | buy | Ø5 with D-flat | |
| Crank discs | Counterweighted crank discs | cw-crank-disc-stroke20 STEP · STL cw-crank-disc-stroke15 STEP · STL | 2 | 90° apart, displacer leads | ||
| Crank pins | Dowel pins | dowel-3x12 STEP · STL | 2 | buy | press fit | |
| Rod clevis | Stirling linkage fittings | rod-clevis-3mm STEP · STL | 1 | grub on the Ø3 displacer rod; conrod-50's 623 end on its Ø3 pin | ||
| Con-rods | Crank discs | conrod-50 STEP · STL conrod-40 STEP · STL | 2 | 50 displacer, 40 piston | ||
| Flywheel | Crank discs | flywheel-100 STEP · STL | 1 | Ø8 bore + bolt-on-counterweight-r20 | ||
| Shaft adapter | Stirling linkage fittings | shaft-adapter-5-to-8 STEP · STL | 1 | puts the Ø8 flywheel on the Ø5 crankshaft | ||
| Collars / clips | Shafts | collar-5mm STEP · STL eclip-5mm STEP · STL | 2 | buy | locate the shaft | |
| Fasteners | Socket head cap screws | shcs-m3x8 STEP · STL shcs-m3x10 STEP · STL shcs-m3x16 STEP · STL | 20 | buy | + M3 nuts, M5 × 10 button heads, inserts | |
| Heat | Tea lights | tea-light-38x16 STEP · STL | 1 | buy | 15–20 mm below the cap | |
| Instruments | Instrumentation | probe-clamp-k-type-3mm STEP · STL probe-clamp-ds18b20-6mm STEP · STL hall-sensor-mount-to92 STEP · STL | 3 | optional | ||
| Calibrate first | Printer calibration coupons | hole-gauge-m3-2-8-to-3-6 STEP · STL pin-gauge-2-8-to-3-2 STEP · STL bearing-pocket-gauge-623-625-608 STEP · STL | 1 | once per printer |
Build order
- Print the calibration coupons and set your slicer offsets.
- Print displacer, cap, heads, crank discs, con-rods, flywheel, stands, base plate, liner (or buy a glass tube + graphite piston).
- Buy: spool, two clamps + gaskets, six bearings, M3/M5 screws, 3/32 in brass tube, #100 mesh, 4 mm silicone tube, tea light.
- Assemble displacer on its rod; press the cap; rod through the guide in the cold head.
- Clamp spool between hot cap and cold head with the regenerator cage in the gap.
- Base plate on 2020; stands and crankshaft on the plate; crank discs 90° apart, displacer leading.
- Con-rods to the rod and the piston (crosshead if lapped); flywheel with the counterweight arc opposite the heavier pin.
- Transfer tube to the power cylinder; tea light 15–20 mm under the hot cap; turn the flywheel to start.
Long Earth Society articles: displacer build full finned tri clamp heat sink temp rpm measurements self starting stirling
Agents: each row's object has /api/geometry?object=slug and the MCP tool get_free_files; the STL list above is the whole print job.