# LTD crank stand for a 623 bearing, axis 112 above the foot

> What are the dimensions of the crank stand on a coffee-cup Stirling engine?

- Category: Stirling engines › Can & LTD engines
- Kind: Hardware
- Basis: 623 bearing (3 × 10 × 4) pocket at the bearing OD; M3 clearance Ø3.4 (ISO 273)
- Page: https://xemstudio.com/objects/ltd-crank-stand/ · JSON: https://xemstudio.com/api/geometry?object=ltd-crank-stand · Plain text: https://xemstudio.com/objects/ltd-crank-stand/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 bearing stand that holds the LTD engine's Ø3 crankshaft above the top plate: a 40 × 6 upright, 119 tall, with a 28 × 14 arch under it that straddles the plate's bosses, on two 20 × 10 × 3 feet (one 68 mm foot with the arch cut out).
- A Ø10 pocket through the 6 mm upright, 112 mm above the foot's underside, holds a 623 bearing (fit: press). That height is what the con-rod needs to reach a piston inside the 90 mm syringe barrel standing in the top plate.
- Two Ø3.4 holes 54 mm apart in the feet take M3 × 8 screws into the top plate's tapped pads. Two stands carry one crankshaft, with the flywheel between them.

## 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 |
|---|---|---|---|---|
| stand bearing pockets | Ø10 | 623 bearing | press | ltd-crank-stand-* |
| stand foot holes | Ø3.4 | M3 screw clearance (ISO 273) | designed | ltd-crank-stand-* |
| stand arch | 28 × 14 | top-plate bosses (no contact) | designed | ltd-crank-stand-* |

## Sizes

| part | height | shaft axis | pocket | feet | holes |
|---|---|---|---|---|---|
| ltd-crank-stand-a112 | 119 | 112 | Ø10 × 6 | 68 × 10 × 3 less the 28 arch | 2 × Ø3.4 at 54 |

## Where the files are

- Wikipedia: [Stirling engine](https://en.wikipedia.org/wiki/Stirling_engine) — web — CC BY-SA 4.0 (text)
- James R. Senft: [An Introduction to Low Temperature Differential Stirling Engines](https://www.stirlingengine.com/) — book — Moriya Press (verify at link)
- Long Earth Society: [Engine 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/ltd-crank-stand/index.json

- ltd-crank-stand-a112: [STEP](https://xemstudio.com/files/hardware/ltd-coffee-cup-engine-kit/ltd-crank-stand-a112.step) · [STL](https://xemstudio.com/files/hardware/ltd-coffee-cup-engine-kit/ltd-crank-stand-a112.stl) — crank stand: upright 40 × 6 × 119, Ø10 pocket through it for a 623 with its axis 112 above the foot, 28 × 14 arch under it, 68 × 10 × 3 foot with 2 × Ø3.4 at 54 mm (two per engine)

## How it fits

### Goes in or on
- [LTD Stirling top plate with syringe socket, Ø120 and Ø170](https://xemstudio.com/objects/ltd-top-plate/): 2 × M3 down onto the top plate
- [Ball bearings, 683 to 6210 and flanged F6xx (ISO 15)](https://xemstudio.com/objects/ball-bearings-metric/): 623 in the Ø10 pocket

### Connects to
- [Crankshafts Ø3, Ø5 and Ø8 with full-length D-flat](https://xemstudio.com/objects/stirling-crankshafts/): Ø3 crankshaft through the 623s

### Alternatives
- [Crank stand for a 623 bearing, 40 / 60 / 80 mm](https://xemstudio.com/objects/can-engine-crank-stand/): 40 / 60 / 80 mm stands

## Questions

**What bearing goes in the LTD crank stand?**

A 623 (3 × 10 × 4) in the Ø10 pocket, 112 mm up.

**How many stands does the LTD engine use?**

Two, 20 mm apart along the Ø3 × 40 crankshaft, with the flywheel between them and a crank disc outside each.

## Fits with

- [LTD Stirling top plate with syringe socket, Ø120 and Ø170](https://xemstudio.com/objects/ltd-top-plate/)
- [Crank stand for a 623 bearing, 40 / 60 / 80 mm](https://xemstudio.com/objects/can-engine-crank-stand/)
- [Ball bearings, 683 to 6210 and flanged F6xx (ISO 15)](https://xemstudio.com/objects/ball-bearings-metric/)
- [Crankshafts Ø3, Ø5 and Ø8 with full-length D-flat](https://xemstudio.com/objects/stirling-crankshafts/)
- [Build list: LTD coffee-cup engine](https://xemstudio.com/objects/list-ltd-coffee-cup/)