Flexure stack spacer ring: Ø40 to Ø120 × 2 mm — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/flexure-stack-spacer/  (CC BY 4.0)
Basis: Ring = the flexure rim: OD × (OD − 2 × 0.12 OD), 2 mm thick
Catalog version: 2026-10-20

Sizes: see table below
- A plain ring the size of a flexure leaf's rim, 2 mm thick, that sits between leaf rims so the arms can flex without touching.
- Ø40 × 4.8 wide, Ø60 × 7.2, Ø80 × 9.6, Ø100 × 12, Ø120 × 14.4; all 2.0 mm thick, with no rim holes.

od_mm  id_mm  width_mm  thickness_mm
40  30.4  4.8  2
60  45.6  7.2  2
80  60.8  9.6  2
100  76  12  2
120  91.2  14.4  2

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- NASA (NTRS, public domain): Free-piston Stirling convertor flexure bearing development and life testing (2005) — PDF — US Government work, public domain — https://ntrs.nasa.gov/search?q=20050182933
- NASA (NTRS, public domain): Flexure bearing design for free-piston Stirling engines (1986) — PDF — US Government work, public domain — https://ntrs.nasa.gov/search?q=19860020334
- NASA (NTRS, public domain): Advanced Stirling Radioisotope Generator (ASRG) engineering unit (2011) — PDF — US Government work, public domain — https://ntrs.nasa.gov/search?q=20110016393
- Wikipedia: Flexure bearing — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Flexure_bearing
- Sunpower (AMETEK): Free-piston Stirling technology overview — web — Sunpower site [verify license at link] — https://sunpowerinc.com/
- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 5 parts): https://xemstudio.com/files/hardware/flexure-stack-spacer/index.json
API: https://xemstudio.com/api/geometry?object=flexure-stack-spacer