# Coil bobbin Ø10 core × 8 mm, Ø13 flanges

> What size coil bobbin for a small axial flux generator?

- Category: Stirling engines › Generators & instruments
- Kind: Hardware
- Basis: Bobbin sized to the stator pocket: Ø13 flanges, Ø10 core, 8 long, wire slot in one flange
- Page: https://xemstudio.com/objects/coil-bobbin/ · JSON: https://xemstudio.com/api/geometry?object=coil-bobbin · Plain text: https://xemstudio.com/objects/coil-bobbin/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

**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

- The bobbin has a hollow Ø10 core (0.5 mm wall) 8 mm long, closed by two Ø13 × 0.8 mm flanges.
- A 1.2 mm slot across one flange lets the start of the winding out.
- The winding window is 1.5 mm deep (Ø10 to Ø13) and 6.4 mm long between the flanges.
- The Ø13 flanges slide into the Ø13 pockets of the axial-flux stator.

## 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 |
|---|---|---|---|---|
| bobbin flanges | Ø20 | stator coil pocket Ø20 | slide | coil-bobbin-* |

## Sizes

| feature | size_mm |
|---|---|
| core | Ø10 × 8 (Ø9 hollow) |
| flanges | Ø13 × 0.8 |
| winding window | 1.5 deep × 6.4 long |
| wire slot | 1.2 wide |

## Where the files are

- Wikipedia: [Axial flux motor](https://en.wikipedia.org/wiki/Axial_flux_motor) — web — CC BY-SA 4.0 (text)
- Wikipedia: [Alternator](https://en.wikipedia.org/wiki/Alternator) — web — CC BY-SA 4.0 (text)
- Hugh Piggott: [A Wind Turbine Recipe Book (axial-flux alternator design)](http://scoraigwind.co.uk/) — web, PDF — Author's site (verify at link)
- Long Earth Society: [Engine and rig builds](https://longearthsociety.com/engineering/) — web, video — LES site

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

Index: https://xemstudio.com/files/hardware/coil-bobbin/index.json

- coil-bobbin-10x8: [STEP](https://xemstudio.com/files/hardware/axial-flux-generator-kit/coil-bobbin-10x8.step) · [STL](https://xemstudio.com/files/hardware/axial-flux-generator-kit/coil-bobbin-10x8.stl) — coil bobbin Ø10 core (Ø7 bore) × 8 long = the stator thickness, Ø20 × 0.8 flanges, winding window 5 radial × 6.4 axial (32 mm²), 1.2 mm lead slot in one flange

## How it fits

### Goes in or on
- [Axial-flux stator plates: Ø90 9-coil and Ø70 6-coil](https://xemstudio.com/objects/axial-flux-stator/): Ø13 flanges in the Ø13 coil pockets (slide)

### Also needed
- [Axial-flux rotor plates: Ø90 with 12 magnets (Ø8 bore), Ø70 with 8 magnets (Ø5 bore)](https://xemstudio.com/objects/axial-flux-rotor/): magnets pass over the coil faces

## Questions

**What is the winding space on the bobbin?**

1.5 mm radially (Ø10 core to Ø13 flange) by 6.4 mm between the flanges.

**Does the bobbin fit the stator?**

Yes: its Ø13 flanges match the Ø13 coil pockets (slide, see Mating features).

## Fits with

- [Axial-flux stator plates: Ø90 9-coil and Ø70 6-coil](https://xemstudio.com/objects/axial-flux-stator/)
- [Axial-flux rotor plates: Ø90 with 12 magnets (Ø8 bore), Ø70 with 8 magnets (Ø5 bore)](https://xemstudio.com/objects/axial-flux-rotor/)