Linear alternator mover: Ø35 carrier for 16 Ø10 × 3 magnets — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/linear-alternator-mover/  (CC BY 4.0)
Basis: Moving-magnet layout as in Sunpower / NASA convertors; pockets at the Ø10 × 3 disc magnet; checked in the generator (alt_check)
Catalog version: 2026-10-20

Sizes: see table below
- The moving part of the linear alternator: a Ø35 × 26 carrier on a Ø12 × 6 hub, 32 mm overall, with a Ø5 bore (fit: slide) and a Ø2.5 radial hole (M3 tap size) in the hub for a grub screw.
- Two axial rows of 8 pockets (fit: press) for Ø10 × 3 disc magnets, faces out, 12 mm apart along the axis, the second row turned half a pocket. Row 1 all north out, row 2 all south out: the flux through each coil reverses as the mover passes.
- With magnets it is about 58 g, which adds to the piston's moving mass. It clamps the 5 mm piston tube or a Ø5 rod and sits centred in the coils at mid-stroke, 1.0 mm from the bobbin bore.

parameter  value
carrier  Ø35 × 26
hub  Ø12 × 6
bore  Ø5
magnet pockets  2 rows × 8, Ø10 × 3
row pitch  12
air gap to bobbin  1.0
mass with magnets  ≈ 58 g

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- NASA (NTRS, public domain): Linear alternator design for free-piston Stirling convertors (2005) — PDF — US Government work, public domain — https://ntrs.nasa.gov/search?q=20050182934
- NASA (NTRS, public domain): Sunpower/NASA 80 We free-piston Stirling convertor (2002) — PDF — US Government work, public domain — https://ntrs.nasa.gov/search?q=20020047256
- Wikipedia: Linear alternator — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Linear_alternator
- Wikipedia: Free-piston engine — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Free-piston_engine
- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/linear-alternator-mover/index.json
API: https://xemstudio.com/api/geometry?object=linear-alternator-mover