NEMA 34 stepper motor: 86 mm face, 69.6 mm hole pattern — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/nema-34-stepper/  (CC BY 4.0)
Basis: NEMA ICS 16 frame size 34 (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 34 is a 3.4 in face: 86 mm square, with chamfered corners. The face and hole pattern are the standard; the body length is the maker's.
- Four Ø5.5 through holes in the flange on a 69.6 mm square, for screws from the front.
- Pilot boss Ø73 × 1.6; shaft Ø14 × 37 from the boss, D-flat 12.60 across.
- Files: 80, 115 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  86 × 86
hole pattern  69.6 × 69.6
holes  4 × Ø5.5 through
pilot boss  Ø73 × 1.6
shaft  Ø14 × 37, D-flat 12.60 across
body lengths drawn  80, 115

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-34-stepper/index.json
API: https://xemstudio.com/api/geometry?object=nema-34-stepper