Flexible shaft couplers, 5–10 mm bores — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/shaft-couplers/  (CC BY 4.0)
Basis: Common aluminium helical (beam) couplers as sold for 3D printers and CNC kits
Catalog version: 2026-10-20

Sizes: see table below
- Ø19 × 25 mm for 5 → 5 and 5 → 8; Ø25 × 30 mm for 6.35/8/10 mm bores. Two set screws per end at 90°.
- Helical couplers take 0.2 mm misalignment; for a lead screw also add a bearing block at the far end or let the end float.
- Spiral cut is shown as three slots in these files; the envelope is what matters for the print.

bore_1_mm  bore_2_mm  od_mm  length_mm  set_screws
5  5  19  25  M4 × 2 per end
5  8  19  25  M4 × 2 per end
5  8  25  30  M4 × 2 per end
6.35  8  25  30  M4 × 2 per end
8  8  25  30  M4 × 2 per end
8  10  25  30  M4 × 2 per end

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- McMaster-Carr: Shaft couplings (free STEP/IGES/STL per part, for your own design use; no redistribution) — STEP, IGES, STL, PDF — McMaster-Carr site terms: personal design use, no redistribution [verify license at link] — https://www.mcmaster.com/products/shaft-couplings/
- Wikipedia: Coupling — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Coupling

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