Xem Studiomeasured geometryLibrary › Stirling engines › Free-piston ·
Linear alternator cap ring, Ø96 and Ø116
What holds the linear alternator stator in its housing? · Hardware · basis: Same outline and rim circle as the housing's top flange; bore = sleeve bore − 2
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
- 2 in table
Notes
- A flat ring Ø96 (2 in) or Ø116 (3 in) × 4 with a Ø50.5 bore, that holds the back-iron sleeve and bobbin down in the housing.
- 3 × Ø3.4 holes on the same rim circle as the housing (R35.2 / R44): M3 × 12 screws go up through the top flange and cap into the standoffs that carry the flexure ring and stack B.
Sizes
| file | outside | bore | thickness | rim circle |
|---|---|---|---|---|
| alt-cap-2in-flex80 | 96 | 50.5 | 4 | R35.2 |
| alt-cap-3in-flex100 | 116 | 50.5 | 4 | R44 |
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 |
|---|---|---|---|---|
| cap rim holes | Ø3.4 | M3 screw clearance | designed | alt-cap-* |
| cap ring bore | Ø50.5 | holds the sleeve and bobbin down | designed | alt-cap-* |
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 2 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json
| alt-cap-2in-flex80 | 2in cap ring: holds the sleeve and bobbin down on the housing's top flange; 3 × M3 × 12 through flange and cap into the standoffs for flexure stack B | STEP · STL |
| alt-cap-3in-flex100 | 3in cap ring: holds the sleeve and bobbin down on the housing's top flange; 3 × M3 × 12 through flange and cap into the standoffs for flexure stack B | STEP · STL |
Plain text: sheet.txt · JSON: /api/geometry?object=linear-alternator-cap-ring
How it fits
Goes in or on
Linear alternator housing for Ø80 and Ø100 flexureson the top flange, same 3 × M3Connects to
Linear alternator back-iron sleeve Ø60.5 × Ø52.5…holds the sleeve downAlso needed
Threaded standoffs, M2.5 and M3standoffs above for stack BIn 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
What does the alternator cap ring do?
It clamps the sleeve and bobbin down onto the housing's ledge; its Ø50.5 bore overlaps the Ø52.5 sleeve bore by 1 mm all round.
What screws hold the cap ring?
3 × M3 × 12 through the top flange and cap into the standoffs above.