# 2204 brushless outrunner: Ø27.9 × 29.2 mm, 16 × 19 M3 mount

> What are the dimensions of a 2204 brushless motor?

- Category: Electronics › Motors
- Kind: Hardware
- Basis: RCDrone listing of the EMAX MT2204 II drawing values. 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/brushless-outrunner-2204/ · JSON: https://xemstudio.com/api/geometry?object=brushless-outrunner-2204 · Plain text: https://xemstudio.com/objects/brushless-outrunner-2204/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.
- 2204 names the stator: 22 mm diameter, 4 mm tall. The outside below is one maker's 2204; bell size, shaft and mount differ between makers.
- The bell is Ø27.9 and the motor is 29.2 mm tall overall, of which 12.5 is the Ø5 shaft above the bell; the top 7.5 of it is the M5 prop thread (drawn plain at Ø5). The base below the bell is drawn at the bell Ø as an envelope.
- Base mount: four M3 holes in a cross, two 16 mm apart and two 19 mm apart. The listing gives no thread depth, so they are drawn Ø3.0 × 3.0 deep only to mark them.
- The leads and the Ø8 centre boss on the drawing are not drawn (its height is not given).
- In DIY Stirling builds, brushless outrunners are driven by the engine as three-phase generators; the AC from the three leads is rectified for a load.

## 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 | Ø5 (M5 thread on the top 7.5) | pulley, coupler or prop-adapter bore | slide | outrunner-2204* |
| base holes | 4 × M3, cross 16 × 19 (drawn 3.0 deep as position marks) | M3 screws through the mount | designed | outrunner-2204* |
| bell | Ø27.9, turns with the shaft | clearance in the mount (no contact) | designed | outrunner-2204* |

## Sizes

| feature | mm | from |
|---|---|---|
| bell | Ø27.9 | RCDrone / EMAX MT2204 II |
| overall height | 29.2 | RCDrone / EMAX MT2204 II |
| bell and base height | 16.7 (29.2 − 12.5) | RCDrone / EMAX MT2204 II |
| shaft above the bell | Ø5 × 12.5, M5 thread 7.5 | RCDrone / EMAX MT2204 II |
| base holes | 4 × M3, cross 16 × 19 | RCDrone / EMAX MT2204 II |
| stator | 22 × 4 (the name) | size name |

## Where the files are

- RCDrone (EMAX MT2204 II drawing values): [2204 outrunner: Ø27.9, 29.2 overall, M5 shaft 12.5 out (7.5 threaded), 4 × M3 on 16 and 19](https://rcdrone.top/products/mt2204%E2%85%B1-2600kv-brushless-motor-with-cw-ccw-options) — web — listing (verify at link)

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

Index: https://xemstudio.com/files/hardware/brushless-outrunner-2204/index.json

- outrunner-2204: [STEP](https://xemstudio.com/files/hardware/brushless-outrunner-2204/outrunner-2204.step) · [STL](https://xemstudio.com/files/hardware/brushless-outrunner-2204/outrunner-2204.stl) — 2204 outrunner envelope: Ø27.9 × 16.7 bell and base, Ø5 (M5) shaft 12.5 out of the top, 4 × M3 on 16 × 19 cross (3.0 deep position marks)

## How it fits

### Connects to
- [Socket head cap screws, M2–M8 (ISO 4762 / DIN 912)](https://xemstudio.com/objects/socket-head-cap-screws-metric/): four M3 into the base, 16 × 19 cross
- [GT2 timing pulleys, 16T–60T (2 mm pitch)](https://xemstudio.com/objects/gt2-pulleys/): Ø5 bore on the Ø5 shaft (slide)
- [Flexible shaft couplers, 5–10 mm bores](https://xemstudio.com/objects/shaft-couplers/): 5 mm bore on the Ø5 shaft (slide)

### Alternatives
- [Axial-flux rotor plates: Ø90 with 12 magnets (Ø8 bore), Ø70 with 8 magnets (Ø5 bore)](https://xemstudio.com/objects/axial-flux-rotor/): a home-made axial-flux generator instead
- [NEMA 17 stepper motor](https://xemstudio.com/objects/nema-17-stepper/): a stepper run as a two-phase generator

## Questions

**What are 2204 motor dimensions?**

One common 2204 (EMAX MT2204 II) is Ø27.9 × 29.2 mm overall with a Ø5 / M5 shaft 12.5 mm out of the top and four M3 base holes on a 16 × 19 cross.

**What is the 2204 motor mount pattern?**

16 × 19 mm with M3 screws on this motor (two holes 16 apart, two 19 apart). Other makers use 16 × 16 or 12 × 12: check the motor in hand.

**Can a brushless outrunner be used as a generator?**

Yes: turned by an engine it puts out three-phase AC on its three leads; a three-phase bridge rectifier turns it into DC.

## Fits with

- [GT2 timing pulleys, 16T–60T (2 mm pitch)](https://xemstudio.com/objects/gt2-pulleys/)
- [Flexible shaft couplers, 5–10 mm bores](https://xemstudio.com/objects/shaft-couplers/)
- [Set-screw shaft collars Ø3 to Ø12](https://xemstudio.com/objects/shaft-collars/)
- [Optical encoder disc Ø60, 30 slots, Ø5 bore](https://xemstudio.com/objects/encoder-disc/)
- [Axial-flux rotor plates: Ø90 with 12 magnets (Ø8 bore), Ø70 with 8 magnets (Ø5 bore)](https://xemstudio.com/objects/axial-flux-rotor/)
- [Socket head cap screws, M2–M8 (ISO 4762 / DIN 912)](https://xemstudio.com/objects/socket-head-cap-screws-metric/)