# Crank discs for a Ø5 shaft, 10 to 30 mm stroke

> What crank disc gives a 10–30 mm stroke on a 5 mm shaft?

- Category: Stirling engines › Drives & mechanisms
- Kind: Hardware
- Basis: Disc 6 thick, Ø5 bore, Ø3 pin hole at stroke / 2, M3 grub; disc Ø = max(30, stroke + 12)
- Page: https://xemstudio.com/objects/crank-discs-5mm-bore/ · JSON: https://xemstudio.com/api/geometry?object=crank-discs-5mm-bore · Plain text: https://xemstudio.com/objects/crank-discs-5mm-bore/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

- A 6 mm disc with a Ø5 bore and a Ø3 crank-pin hole at half the stroke from the axis: 5.0, 7.5, 10.0, 12.5, 15.0 mm for 10–30 mm stroke.
- Disc Ø grows with the stroke: Ø30 (10 and 15), Ø32 (20), Ø37 (25), Ø42 (30).
- A radial Ø2.5 hole (M3 tap drill) at mid-thickness locks the disc to the shaft's D-flat.
- The crank pin is fixed in the disc and the con-rod's 623 turns on it; fits are under Mating features.

## 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 |
|---|---|---|---|---|
| crank-disc bore | Ø5 | Ø5 crankshaft (M3 set screw) | slide | crank-disc-* |
| crank-disc pin hole | Ø3 | Ø3 crank pin | press | crank-disc-* |
| crank-disc set-screw hole | Ø2.5 | M3 tap drill | designed | crank-disc-* |

## Sizes

| file | stroke | pin offset | disc Ø × t | bore |
|---|---|---|---|---|
| crank-disc-stroke10 | 10 | 5.0 | 30 × 6 | 5 |
| crank-disc-stroke15 | 15 | 7.5 | 30 × 6 | 5 |
| crank-disc-stroke20 | 20 | 10.0 | 32 × 6 | 5 |
| crank-disc-stroke25 | 25 | 12.5 | 37 × 6 | 5 |
| crank-disc-stroke30 | 30 | 15.0 | 42 × 6 | 5 |

## Where the files are

- Wikipedia: [Crank (mechanism)](https://en.wikipedia.org/wiki/Crank_(mechanism)) — web — CC BY-SA 4.0 (text)
- Wikipedia: [Flywheel](https://en.wikipedia.org/wiki/Flywheel) — web — CC BY-SA 4.0 (text)
- Wikipedia: [Stirling engine](https://en.wikipedia.org/wiki/Stirling_engine) — web — CC BY-SA 4.0 (text)
- Long Earth Society: [Engine builds that use these parts (videos and write-ups)](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (5 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/crank-discs-5mm-bore/index.json

- crank-disc-stroke10: [STEP](https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke10.step) · [STL](https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke10.stl) — crank disc for 10 mm stroke (pin at 5.0 mm), Ø5 bore, M3 set screw, Ø3 pin hole
- crank-disc-stroke15: [STEP](https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke15.step) · [STL](https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke15.stl) — crank disc for 15 mm stroke (pin at 7.5 mm), Ø5 bore, M3 set screw, Ø3 pin hole
- crank-disc-stroke20: [STEP](https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke20.step) · [STL](https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke20.stl) — crank disc for 20 mm stroke (pin at 10.0 mm), Ø5 bore, M3 set screw, Ø3 pin hole
- crank-disc-stroke25: [STEP](https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke25.step) · [STL](https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke25.stl) — crank disc for 25 mm stroke (pin at 12.5 mm), Ø5 bore, M3 set screw, Ø3 pin hole
- crank-disc-stroke30: [STEP](https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke30.step) · [STL](https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke30.stl) — crank disc for 30 mm stroke (pin at 15.0 mm), Ø5 bore, M3 set screw, Ø3 pin hole

## How it fits

### Goes in or on
- [Crankshafts Ø3, Ø5 and Ø8 with full-length D-flat](https://xemstudio.com/objects/stirling-crankshafts/): Ø5 bore on the D-flat, M3 grub

### Connects to
- [Connecting rods 30 to 80 mm centres with 623 pockets](https://xemstudio.com/objects/connecting-rods-623/): 623 end on the Ø3 crank pin

### Alternatives
- [Counterweighted crank discs, Ø5 bore, 10 to 30 mm stroke](https://xemstudio.com/objects/counterweighted-crank-discs/): same strokes with a counterweight

### Also needed
- [Crank and wrist pins Ø3 × 12, 16, 19, 20 and 23](https://xemstudio.com/objects/pins-3mm/): Ø3 crank pin

## Questions

**How do I set the stroke on a crank disc?**

Stroke = 2 × pin offset; these discs have the Ø3 pin hole at 5, 7.5, 10, 12.5 and 15 mm.

**What stroke do the 2 in tri-clamp engines run?**

20 mm: crank-disc-stroke20, Ø32 × 6.

## Fits with

- [Connecting rods 30 to 80 mm centres with 623 pockets](https://xemstudio.com/objects/connecting-rods-623/)
- [Counterweighted crank discs, Ø5 bore, 10 to 30 mm stroke](https://xemstudio.com/objects/counterweighted-crank-discs/)
- [Crank discs Ø30 for a Ø3 crankshaft, 10 to 20 mm stroke](https://xemstudio.com/objects/crank-discs-3mm-bore/)
- [Crankshafts Ø3, Ø5 and Ø8 with full-length D-flat](https://xemstudio.com/objects/stirling-crankshafts/)
- [Crank and wrist pins Ø3 × 12, 16, 19, 20 and 23](https://xemstudio.com/objects/pins-3mm/)