Axial-flux alternator kit: magnet rotor plates, 3-phase stator, coil bobbins, hall RPM pickup — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/axial-flux-generator-kit/  (CC BY 4.0)
Basis: Classic coreless axial-flux layout: 12 magnets / 9 coils (3-phase) on Ø90, or 8 / 6 on Ø70; magnets Ø10 × 3 N42 from the library; sized to the Ø8 flywheel shaft and 608 bearings
Catalog version: 2026-10-20

Sizes: see table below
- Rotor: Ø90 plate with 12 Ø10 × 3 magnets on a 72 mm circle, poles alternating N-S around the ring; a second rotor opposite (N facing S across the gap) doubles the flux. Gap rotor-to-rotor 8 mm with a 4 mm stator between. Steel backing plates (1 mm) behind the magnets add ~40% flux.
- Stator: 9 coils on the same 72 mm circle, wired 3-phase (coils 1-4-7, 2-5-8, 3-6-9 in series), rectified with a 3-phase bridge. ~150 turns of 0.3 mm enamelled wire per bobbin ≈ 1.5 Ω; at 600 rpm on the 12-pole rotor expect roughly 4–6 V open circuit per phase and a watt or two into a load: enough for the fan and LEDs, the demonstrator's purpose.
- Frequency = rpm × poles / 120 = 600 × 12 / 120 = 60 Hz. Volts scale with rpm and turns; current with wire gauge; power with magnet count and area. Hall sensor (A3144 or SS49E in the printed mount) facing a rotor magnet gives one pulse per magnet: rpm = pulses × 60 / 12.
- LES: the flywheel alternator on the generator builds; the chain/belt to a NEMA 17 used as a generator is the lazy alternative (the NEMA 17 entry covers it).

part  size  magnets_or_coils  shaft
rotor 90  Ø90 × 5 + hub  12 × Ø10×3  Ø8
rotor 70  Ø70 × 5 + hub  8 × Ø10×3  Ø5
stator 90  Ø90 × 4  9 coils  clears Ø14
stator 70  Ø70 × 4  6 coils  clears Ø11
bobbin  Ø10 × 8, Ø13 flanges  150 t × 0.3 mm  —
hall mount  14 × 10 × 20  TO-92  M3

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Wikipedia: Axial flux motor — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Axial_flux_motor
- Wikipedia: Alternator — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Alternator
- Hugh Piggott: A Wind Turbine Recipe Book (axial-flux alternator design) — web, PDF — Author's site [verify license at link] — http://scoraigwind.co.uk/
- Long Earth Society: Engine and rig builds — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 6 parts): https://xemstudio.com/files/hardware/axial-flux-generator-kit/index.json
API: https://xemstudio.com/api/geometry?object=axial-flux-generator-kit