# 390 size brushed DC motor: Ø27.6 × 47 mm, Ø2.3 shaft

> What are the dimensions of a 390 size DC motor?

- Category: Electronics › Motors
- Kind: Hardware
- Basis: Sigmanortec 390 motor listing (no maker's drawing found). Envelope only: the outside of the motor at its published sizes. The windings, magnets, brushes and bearings inside are not drawn.
- Page: https://xemstudio.com/objects/dc-motor-390-size/ · JSON: https://xemstudio.com/api/geometry?object=dc-motor-390-size · Plain text: https://xemstudio.com/objects/dc-motor-390-size/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part.

## Notes

- Envelope only: the outside of the motor at its published sizes. The windings, magnets, brushes and bearings inside are not drawn.
- The can is Ø27.6 × 47 mm, not counting the bearing sleeves at each end.
- The Ø2.3 shaft is 14 mm from the face, 11 of it beyond the 3 mm front sleeve. The sleeves' diameter is not listed, so they are not drawn.
- Two 2.5 mm screw holes 16 mm apart in the face (the same spacing as the 380 family), drawn 2.0 deep only to mark them; the listing gives no thread or depth.
- Terminal tabs and the wire exit are not drawn. Only one listing gave these sizes; check the motor in hand.
- In DIY Stirling builds, brushed DC motors of this kind are turned by the engine and used as a generator (an LED, a resistor or a meter across the leads) or as a load on the flywheel shaft.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| shaft | Ø2.3 | pinion or pulley bore (pressed on) | press | dc-390-* |
| mounting holes | 2 × Ø2.5 on 16 (drawn 2.0 deep as position marks) | screws through the mount | designed | dc-390-* |
| can | Ø27.6 | cradle | socket | dc-390-* |

## Sizes

| feature | mm | from |
|---|---|---|
| can | Ø27.6 × 47 (without sleeves) | Sigmanortec |
| shaft | Ø2.3 | Sigmanortec |
| shaft from the face | 14 (11 beyond the sleeve) | Sigmanortec |
| front sleeve height | 3 | Sigmanortec (14 − 11) |
| face holes | 2 × Ø2.5 on 16 | Sigmanortec |

## Where the files are

- Sigmanortec: [390 motor listing: Ø27.6, 47 long without the bearing sleeves, shaft Ø2.3 × 14 (11 beyond the sleeve), 2.5 mm screw holes 16 mm apart](https://sigmanortec.ro/en/motor-390-6-24v-13000rpm-shaft-23x14mm) — web — listing (verify at link)

## Free STEP/STL (1 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/dc-motor-390-size/index.json

- dc-390-size: [STEP](https://xemstudio.com/files/hardware/dc-motor-390-size/dc-390-size.step) · [STL](https://xemstudio.com/files/hardware/dc-motor-390-size/dc-390-size.stl) — 390 size envelope: Ø27.6 × 47 can, Ø2.3 shaft 14 from the face, two Ø2.5 screw holes on 16 (2.0 deep position marks)

## How it fits

### Alternatives
- [380 / 385 size brushed DC motor: Ø27.7 × 37.8 mm, 2 × M2.6 on 16](https://xemstudio.com/objects/dc-motor-380-size/): same 16 mm face holes, 37.8 can

### Also needed
- [Through-hole LEDs: 3, 5, 8, 10 mm, flat-top, rectangular, RGB](https://xemstudio.com/objects/leds-tht/): an LED across the leads shows generator output

## Questions

**What are 390 motor dimensions?**

About Ø27.6 × 47 mm without the sleeves, Ø2.3 shaft 14 mm from the face, two 2.5 mm screw holes 16 mm apart (one seller's listing).

**Do 380 mounts fit a 390?**

The face hole spacing is the same 16 mm and the can Ø is within 0.1 mm; the 390 can is about 9 mm longer.

## Fits with

- [380 / 385 size brushed DC motor: Ø27.7 × 37.8 mm, 2 × M2.6 on 16](https://xemstudio.com/objects/dc-motor-380-size/)
- [360 / 365 size brushed DC motor: Ø27.7 × 32.6 mm, 2 × M2.6 on 16](https://xemstudio.com/objects/dc-motor-365-size/)
- [540 size brushed DC motor: Ø35.8 × 50.0 mm, 2 × M3 on 25](https://xemstudio.com/objects/dc-motor-540-size/)