Linear alternator back-iron sleeve Ø60.5 × Ø52.5 × 30 — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/linear-alternator-back-iron-sleeve/  (CC BY 4.0)
Basis: Tube at the sizes in the generator: OD 60.5, bore 52.5 (the bobbin flange OD), length 30 (the bobbin length)
Catalog version: 2026-10-20

Sizes: see table below
- The outer flux return of the alternator: a tube Ø60.5 × Ø52.5 bore × 30 long.
- The bobbin slides into its bore (Ø52.5, fit: slide) and it sits in the housing's Ø60.5 pocket (fit: socket) on a 2 mm ledge, held down by the cap ring.
- The magnetic gap from magnet face to the sleeve is 8.8 mm.

parameter  value
outside  60.5
bore  52.5
length  30

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-back-iron-sleeve/index.json
API: https://xemstudio.com/api/geometry?object=linear-alternator-back-iron-sleeve