Flywheel crank: Ø100 nut-pocket flywheel with a 7.5 mm crank pin (15 mm stroke) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/flywheel-crank/  (CC BY 4.0)
Basis: The Ø100 M8 nut-pocket flywheel (tools/gen_shafts_flywheels.py) with one added Ø3 pin hole through the hub at 7.5 from the axis
Catalog version: 2026-10-20

Sizes: see table below
- Same wheel as flywheel-100-m8-b3 (12 M8 pockets at R40.5, Ø3 hub with M3 grub), plus a Ø3 hole through the hub at 7.5 from the axis, 90° from the grub, for a dowel-3x16 crank pin (10 in the hub, through a 5 mm con-rod, 1 proud). Overhung at a shaft end with the hub toward the con-rod: on the mug LTD it is the displacer crank (the web on the far side, so the displacer clevis passes under the rim); on the test-tube marble engine it drives the rocking link.
- Six M8 nuts in alternate pockets to start.

feature  value_mm
diameter  100
crank throw  7.5
pin hole  Ø3 through the 12.3 hub
bore  Ø3

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- 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/flywheel-crank/index.json
API: https://xemstudio.com/api/geometry?object=flywheel-crank