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Rhombic drive crank pin Ø3 × 17
What size crank pin does the rhombic drive gear take? · Hardware · basis: Ø3 pin at the gear's Ø3 crank-pin hole; 0.4 chamfer on one end; length = gear web + 1 mm + two links
Long Earth Society build part. The balanced beta drive for the 2 in tri-clamp engine; the rhombic frame head in the linkage fittings carries it on the spool. The engines
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. Mating features
- sizes
- 3 in table
Notes
- The crank pin pressed into each rhombic gear 7 mm off its axis: Ø3 × 17 with a 0.4 mm chamfer on one end.
- It runs from the gear web's back face through the web (6, fit: press), a 1 mm gap and the lower and upper links (5 each, fit: run), ending flush with the upper link.
Sizes
| parameter | value |
|---|---|
| diameter | 3 |
| length | 17.0 |
| chamfer | 0.4 |
Mating features
Drawn at the exact size. Open press, slide, run and socket features by your process's clearance; leave designed gaps and clamp fits as drawn.
| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| crank pin | Ø3 × 17 | gear pin hole (press) and two link ends (run) | press | crank-pin-* |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| Wikipedia | Rhombic drive | web | CC BY-SA 4.0 (text) |
| Wikipedia | Stirling engine | web | CC BY-SA 4.0 (text) |
| Philips Research / Meijer | The Philips Stirling engine (rhombic drive papers, 1958–1965) | web | reference verify |
| Long Earth Society | Engine builds | web, video | LES site |
Free files
★ Free files 1 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json
| crank-pin-3x17 | Ø3 × 17 crank pin: through the gear web, a 1 mm gap, the lower and the upper link | STEP · STL |
Plain text: sheet.txt · JSON: /api/geometry?object=rhombic-crank-pin
How it fits
Goes in or on
Rhombic drive crank gear, module 1.5, 44 T, 7 mm…pressed in the Ø3 hole at 7 mmConnects to
Rhombic drive link, 30 mm centrestwo links turn on itAlternatives
Crankshafts Ø3, Ø5 and Ø8 with full-length D-flatØ3 pinsIn these build lists
Beta Stirling, rhombic drive, 2 in tri-clampDisplacer and piston in one bore, driven by two counter-rotating gears on a rhom…You might also need
Questions
What pin goes in the rhombic crank gear?
A Ø3 × 17 pin pressed into the Ø3 hole 7 mm off centre; two links turn on it.
Why is the crank pin 17 mm long?
Gear web 6 + 1 mm gap + two 5 mm links: it ends flush with the outer link, short of the yokes' plane.