Flywheels Ø100–Ø200 with hex-nut rim pockets — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/nut-pocket-flywheels/ (CC BY 4.0) Basis: Rim of hex pockets at the nut's across-flats, one flat facing out, depth = nut thickness; pocket count a multiple of 6 Catalog version: 2026-10-20 Sizes: see table below - A rim of hex pockets, each at the nut's exact across-flats with one flat facing outward and as deep as the nut is thick, on a 1.5 mm floor; a nut sits flush with the face. - Pocket counts are multiples of six: all, every other one, every third or one half can be filled and the wheel stays balanced, or one half only makes a counterweight opposite the crank pin. - Rim thickness = nut thickness + 1.5; rim radial width = across-flats + 6. A 4 mm web with six round windows joins the rim to a hub Ø20 (Ø3 and Ø5 bore) or Ø22 (Ø8 bore), 4 mm taller than the rim. - Each hub has a radial Ø2.5 hole (M3 tap drill) for a grub on the shaft's D-flat. Ø3 hubs exist on the Ø100 and Ø120 wheels only. OD nut pockets pocket circle R rim thickness rim width hub bores 100 M8 12 40.5 8.3 19.0 Ø20 / Ø22 × 12.3 3 / 5 / 8 120 M10 12 49.0 9.9 22.0 Ø20 / Ø22 × 13.9 3 / 5 / 8 120 3/8 in 12 49.9 9.8 20.3 Ø20 / Ø22 × 13.8 3 / 5 / 8 150 M10 18 64.0 9.9 22.0 Ø20 / Ø22 × 13.9 5 / 8 150 M12 12 63.0 12.3 24.0 Ø20 / Ø22 × 16.3 5 / 8 150 1/2 in 12 62.5 12.6 25.1 Ø20 / Ø22 × 16.6 5 / 8 200 M12 18 88.0 12.3 24.0 Ø20 / Ø22 × 16.3 5 / 8 200 1/2 in 18 87.5 12.6 25.1 Ø20 / Ø22 × 16.6 5 / 8 Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - ISO: ISO 4032 Hexagon regular nuts (style 1) — standard — ISO [verify license at link] — https://www.iso.org/standard/72624.html - ASME: ASME B18.2.2 Nuts for general applications — standard — ASME [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/b18-2-2-nuts-for-general-applications-machine-screw-nuts-hex-square-hex-flange-coupling-nuts-(inch-series) - Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/ Free files (CC BY 4.0, Xem Studio; STEP + STL, 19 parts): https://xemstudio.com/files/hardware/nut-pocket-flywheels/index.json API: https://xemstudio.com/api/geometry?object=nut-pocket-flywheels