# Test-tube marble engine base

> What base does a test-tube marble engine stand on?

- Category: Hardware › Stirling & thermoacoustic
- Kind: Hardware
- Basis: My geometry: holes on the pivot posts' and crank stands' foot patterns, M3 nut pockets at the nuts' exact 5.5 AF
- Page: https://xemstudio.com/objects/marble-engine-base/ · JSON: https://xemstudio.com/api/geometry?object=marble-engine-base · Plain text: https://xemstudio.com/objects/marble-engine-base/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

- 438 × 100 × 8 (y −60..40). Two beam-pivot-post-60 at x 0, y ±10 (M3 × 12, nuts flush with the underside) and two crank-stand-80 at x 192.72, y −13.5 and −45.2 (M3 × 10, nuts 1 above the underside).

## 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 |
|---|---|---|---|---|
| screw holes | Ø3.4 | M3 clearance | designed | all |
| nut pockets | 5.5 AF hex | ISO 4032 M3 nut | press | all |

## Sizes

| feature | value |
|---|---|
| base | 438 × 100 × 8 |
| pivot posts | x 0, y ±10 |
| crank stands | x 192.72 |

## Where the files are

- 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/marble-engine-base/index.json

- marble-engine-base: [STEP](https://xemstudio.com/files/hardware/marble-engine-base/marble-engine-base.step) · [STL](https://xemstudio.com/files/hardware/marble-engine-base/marble-engine-base.stl) — base 438 × 100 × 8 (y −60..40): 4 × Ø3.4 for the two pivot posts and 4 for the two crank stands, each with an M3 nut pocket (5.5 AF) from the underside

## Questions

**How long is the marble engine?**

The base is 438 mm: tube, stopper, transfer line, glass syringe and crank in one line.

## Fits with

- [Build list: Test-tube marble engine](https://xemstudio.com/objects/list-test-tube-marble-engine/)
- [Borosilicate test tubes, 10×75 to 30×200 mm](https://xemstudio.com/objects/borosilicate-test-tubes/)
- [Glass marbles 1/2 in, 5/8 in and Ø16 mm](https://xemstudio.com/objects/glass-marbles/)
- [Glass syringes 1–50 mL (all-glass, ground-glass plunger): barrel and plunger](https://xemstudio.com/objects/glass-syringes/)
- [Laboratory rubber stoppers #0–#13 (25 mm tall)](https://xemstudio.com/objects/rubber-stoppers/)
- [Beam pivot post, 60 mm](https://xemstudio.com/objects/beam-pivot-post/)