# Build list: Test-tube marble engine

> What parts do I need to build a test-tube marble Stirling engine?

- Category: Stirling engines › Guide
- Kind: List / guide
- Basis: Every part is a free file on this site.
- Page: https://xemstudio.com/objects/list-test-tube-marble-engine/ · JSON: https://xemstudio.com/api/geometry?object=list-test-tube-marble-engine · Plain text: https://xemstudio.com/objects/list-test-tube-marble-engine/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- crank and flywheel at the end.
- Numbers: 25 × 150 tube · 4 marbles Ø15.875 (5/8 in) · 5 mL glass syringe, plunger travel 2.1..16.6 out · rocker -7.9..7.9° · rocking pin 90° ahead · Ø100 flywheel crank · both cranks overhung

## Sizes

| subsystem | object | parts | qty | note |
|---|---|---|---|---|
| Base | marble-engine-base | marble-engine-base | 1 |  |
| Pivot posts | beam-pivot-post | pivot-post-60 | 2 | y ±10 |
| Pivot pin | dowel-pins-metric | dowel-3x30 | 1 | through both posts and the rocker hub |
| Rocker | marble-engine-rocker | marble-engine-rocker-25x150-glass5 | 1 |  |
| Displacer cylinder | borosilicate-test-tubes | test-tube-25x150 | 1 | closed end is the hot end |
| Displacer | glass-marbles | marble-5-8in | 4 | roll end to end as it rocks |
| Stopper | rubber-stoppers | stopper-4-bore-4 | 1 | #4 bored Ø4 for the 4 mm tube |
| Transfer tube | brass-tube-ks | brass-4mm | 1 | through the stopper |
| Transfer hose | silicone-tube | silicone-tube-4x6-50 | 1 | 4 mm tube to Luer cone, straight |
| Power cylinder | glass-syringes | glass-syringe-5ml-barrel | 1 | in the rocker's ring |
| Power piston | glass-syringes | glass-syringe-5ml-plunger | 1 |  |
| Plunger clevis | glass-syringe-plunger-clevis | plunger-clevis-glass-5ml | 1 |  |
| Crank stands | can-engine-crank-stand | crank-stand-80 | 2 | 623 pockets, axis 80 above the base |
| Bearings | ball-bearings-metric | bearing-623 | 2 |  |
| Crankshaft | stirling-crankshafts | crankshaft-3x60 | 1 | along y, both cranks overhung |
| Power crank | crank-discs-3mm-bore | crank-disc-b3-stroke15 | 1 | syringe end |
| Flywheel crank | flywheel-crank | flywheel-crank-100-m8-b3-s15 | 1 | rocking end, its pin 90° ahead of the power pin |
| Flywheel weights | hex-nut-weights | nut-m8 | 6 | alternate pockets |
| Con-rod | pin-end-con-rods | conrod-45 | 1 | power pin to plunger clevis |
| Rocking link | marble-engine-rocking-link | rocking-link-170 | 1 | flywheel-crank pin to the lever pin |
| Crank pin (flywheel) | dowel-pins-metric | dowel-3x16 | 1 | 10 in the hub, through the link, 1 proud |
| Pins | dowel-pins-metric | dowel-3x12 | 3 | power crank pin, clevis pin, lever pin |
| Post screws | socket-head-cap-screws-metric | shcs-m3x12 | 4 |  |
| Stand screws | socket-head-cap-screws-metric | shcs-m3x10 | 4 |  |
| Nuts | hex-nuts-metric | nut-m3 | 8 | in the base's pockets |
| Grub screws | set-screws-metric | set-m3x4 | 2 | tube ring and syringe ring |
| Grub screw | set-screws-metric | set-m3x10 | 1 | power crank disc |
| Grub screw | set-screws-metric | set-m3x8 | 1 | flywheel-crank hub |
| Grub screw | set-screws-metric | set-m3x3 | 1 | plunger clevis |
| Heat | tea-light-candles | tea-light-38x16 | 1 | optional: under the closed end |

## Where the files are

- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Build order

1. Base: pivot posts and crank stands with M3 screws into the nut pockets.
2. Stopper bored for the 4 mm tube; marbles in the tube; stopper in; tube into the rocker's Ø25 ring; grub.
3. Silicone tube over the 4 mm tube; grub. Plunger in, clevis cap on its collar.
4. Rocker on the posts with a dowel-3x30. 623s, crankshaft, power crank disc at the syringe end and the flywheel crank at the other (its pin 90° ahead), six M8 nuts.
5. Con-rod from the power pin to the plunger clevis; rocking link from the flywheel-crank pin to the rocker's lever pin. Tea light under the closed end.

All printed STLs: https://xemstudio.com/objects/list-test-tube-marble-engine/stl-list.txt

## Questions

**What parts do I need to build a test-tube marble Stirling engine?**

30 parts, every one a free STEP/STL on this site; see the table and the build order on this page.

## Fits with

- [Test-tube marble engine rocker: tube and glass-syringe rings on a pivot](https://xemstudio.com/objects/marble-engine-rocker/)
- [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/)