8520 (820) coreless motor: Ø8.5 × 20 mm, Ø1 shaft — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/coreless-motor-8520/  (CC BY 4.0)
Basis: DFRobot FIT0796 and Makeblock 820 listings (they agree). Envelope only: the outside of the motor at its published sizes. The windings, magnets, brushes and bearings inside are not drawn.
Catalog version: 2026-10-20

Sizes: see table below
- Envelope only: the outside of the motor at its published sizes. The windings, magnets, brushes and bearings inside are not drawn.
- The body is a plain Ø8.5 × 20 mm cylinder; the Ø1.0 shaft stands 5 mm out of the front end.
- 8520 and 820 are the same size: 8.5 mm diameter, 20 mm long.
- The leads leave the back end; they and any bearing boss are not drawn (not listed). It is held by its body in a Ø8.5 clip or socket.
- Coreless motors have no iron in the rotor, so they turn without cogging; on small, low-power Stirling models they are used as generators or tachometer pickups.

feature  mm  from
body  Ø8.5 × 20  DFRobot FIT0796, Makeblock 820
shaft  Ø1.0 × 5  DFRobot FIT0796, Makeblock 820

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- DFRobot (FIT0796, as listed by Core Electronics): Coreless micro motor 8.5 × 20 mm: Ø8.5 × 20, shaft Ø1 × 5 — web — listing [verify license at link] — https://core-electronics.com.au/4pcs-coreless-micro-motor-8-5-20mm.html.plain.md
- Makeblock (as listed by Studica): 820 coreless motor: Ø8.5 × 20, output shaft Ø1.0 × 5 — web — listing [verify license at link] — https://www.studica.com/makeblock-820-coreless-motor-pair

Free files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/coreless-motor-8520/index.json
API: https://xemstudio.com/api/geometry?object=coreless-motor-8520