Linear alternator module mover: Ø48 piston cup, 40-magnet carrier and tube rod, sprung on two leaves — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/linear-alternator-module-mover-2in/  (CC BY 4.0)
Basis: Design values; moving mass from the CAD volumes at 7.9 g/cm³ (metal parts, assumed) and 7.5 g/cm³ (magnets, published), each leaf adding its hub and a third of its arms
Catalog version: 2026-10-20

Sizes: see table below
- Three parts and the magnets: a piston cup whose Ø48.00 × 24 land is the clearance seal in the 42 mm bored spool; a Ø18 tube rod pressed into the cup's socket; a Ø47 × 56 magnet carrier pressed on the tube in the 3 in bored spool, with the 40 Ø12 × 3 disc magnets of the free-piston generator in four rows (S, N, N, S from face A), faces out.
- The tube rod carries the hubs of leaf 1 (between the two bored spools) and leaf 2 (between the 3 in spool and the 25.4 mm spool) on four Ø28 collars: the magnets sit between the two leaves, so the stator's side pull acts between its supports and the cup's land runs on the axis without touching.
- The carrier's body is the magnetic return between the magnet rows, so it must be magnetically soft; the cup and tube only have to be stiff. Moving mass of the standard build: 865 g (piston cup 184, magnet carrier 428, tube rod 86, magnets (40) 102, collars (4) 56, grub screws (4) 1, leaves 1, 2 (share) 7 g).
- The cup is open toward face B: its inside is part of the bounce space. Its crown has three M3 tapped holes for the add-on mass discs (tuning page). At mid-stroke the crown face is 9.00 mm inside face A: a depth gauge on the crown is the module's centring check.
- The same mover serves both versions of the module. Only the tube rod differs: 108.15 long in the closed module (leaves 77.9 apart in the spool joints), 151.70 in the open frame (leaves 93.0 apart on the frame's seats).

part  size
la-piston-cup-48x24  Ø48.00 × 24 land, crown 5
la-magnet-carrier-47x56  Ø47 × 56, 40 pockets Ø12 × 3
la-tube-rod-18x14x108.15  Ø18 / Ø14 × 108.15 (closed)
la-tube-rod-18x14x151.70  Ø18 / Ø14 × 151.70 (open frame)
magnets  40 × Ø12 × 3, rows S N N S at 14 pitch
moving mass  865 g closed, 899 g open frame (standard build)

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- K&J Magnetics: Neodymium magnet specifications: N42 Br 1.30–1.32 T, density 7.4–7.5 g/cm³ — web — maker page; values are facts [verify license at link] — https://www.kjmagnetics.com/specs.asp
- Xem Studio: tools/gen_la_module.py: the module's geometry, masses, bounce volume, natural frequencies and every number on these pages — code — CC BY 4.0 — https://xemstudio.com/
- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 4 parts): https://xemstudio.com/files/hardware/linear-alternator-module-mover-2in/index.json
API: https://xemstudio.com/api/geometry?object=linear-alternator-module-mover-2in