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Linear alternator bobbin: Ø37 bore, two 10 mm bays
What are the dimensions of the coil bobbin for a linear alternator? · Hardware · basis: Bore = mover Ø35 + 2 × 1.0 gap; flanges at the back-iron sleeve bore Ø52.5; length = sleeve length 30
Long Earth Society build part. Power take-off on the LES free-piston test bed. 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
- 7 in table
Notes
- The coil former of the alternator stator: Ø37 bore (1.0 mm air gap to the Ø35 mover), Ø38.6 core, 30 long, so the coil pair is centred in the 30 mm sleeve.
- Flanges are Ø52.5, the back-iron sleeve's bore (fit: slide): 4 mm end flanges and a 2 mm divider make two 10 mm winding bays.
- Lead-out slots in both end flanges and a crossover notch in the divider; the second bay is wound the opposite way and joined to the first in series.
Sizes
| parameter | value |
|---|---|
| bore | 37 |
| core OD | 38.6 |
| flange OD | 52.5 |
| length | 30 |
| bays | 2 × 10 |
| divider | 2 |
| end flanges | 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 |
|---|---|---|---|---|
| mover-to-bobbin gap | 1.0 radial | bobbin bore | designed | alt-bobbin-* |
| bobbin flanges in the sleeve | Ø52.5 | back-iron sleeve bore | slide | alt-bobbin-* |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| NASA (NTRS, public domain) | Linear alternator design for free-piston Stirling convertors (2005) | US Government work, public domain | |
| NASA (NTRS, public domain) | Sunpower/NASA 80 We free-piston Stirling convertor (2002) | US Government work, public domain | |
| Wikipedia | Linear alternator | web | CC BY-SA 4.0 (text) |
| Wikipedia | Free-piston engine | web | CC BY-SA 4.0 (text) |
| 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
| alt-bobbin-37-2x10 | bobbin: Ø37 bore (1 mm air gap to the mover), two 10 mm bays split by a 2 mm divider with a crossover notch, 30 long, slides into the back-iron sleeve | STEP · STL |
Plain text: sheet.txt · JSON: /api/geometry?object=linear-alternator-bobbin
How it fits
Goes in or on
Linear alternator back-iron sleeve Ø60.5 × Ø52.5…Ø52.5 flanges in the sleeve boreConnects to
Linear alternator coil Ø50 × 10a coil in each bay
Linear alternator movermover inside, 1.0 mm gapIn these build lists
Free-piston Stirling, 2 in tri-clampNo crank: piston and displacer each hang on a stack of spiral flexures, with a t…You might also need
Questions
How big is the air gap in the linear alternator?
1.0 mm radial: Ø37 bobbin bore over the Ø35 mover.
Why does the bobbin have two bays?
One coil over each magnet row, wound in opposite directions and joined in series.