NEMA 8 stepper motor: 20.2 mm face, 16 mm hole pattern — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/nema-8-stepper/  (CC BY 4.0)
Basis: NEMA ICS 16 frame size 8 (face and mounting-hole pattern); pilot boss and shaft as commonly supplied; body length varies with torque. Envelope only: the outside of the motor. The windings, rotor and bearings inside are not drawn.
Catalog version: 2026-10-20

Sizes: see table below
- Envelope only: the outside of the motor. The windings, rotor and bearings inside are not drawn.
- NEMA 8 is a 0.8 in face: 20.2 mm square, with chamfered corners. The face and hole pattern are the standard; the body length is the maker's.
- Four M2 tapped holes on a 16 mm square, drawn as plain bores at the thread's major diameter (Ø2) 8 mm deep.
- Pilot boss Ø15 × 1.5; shaft Ø4 × 10 from the boss.
- Files: 30, 38 mm bodies. Leads and connector are not drawn.
- In DIY Stirling builds, a stepper turned by the engine is used as a two-phase generator; each coil pair gives AC that is rectified for a load.

feature  mm
face  20.2 × 20.2
hole pattern  16 × 16
holes  4 × M2 tapped
pilot boss  Ø15 × 1.5
shaft  Ø4 × 10
body lengths drawn  30, 38

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Wikipedia: Stepper motor — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Stepper_motor
- NEMA: ICS 16 motion/position control motors and controls — PDF — NEMA standard, purchase — https://www.nema.org/standards/view/motion-position-control-motors-controls-and-feedback-devices

Free files (CC BY 4.0, Xem Studio; STEP + STL, 2 parts): https://xemstudio.com/files/hardware/nema-8-stepper/index.json
API: https://xemstudio.com/api/geometry?object=nema-8-stepper