# Threaded rod, metric: M4 × 194.2

> How long a rod carries the flexures of the 2 in free-piston mover?

- Category: Stirling engines › Drives & mechanisms
- Kind: Hardware
- Basis: ISO metric M4; thread drawn as the plain major diameter, this site's convention
- Page: https://xemstudio.com/objects/threaded-rods-metric/ · JSON: https://xemstudio.com/api/geometry?object=threaded-rods-metric · Plain text: https://xemstudio.com/objects/threaded-rods-metric/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**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

- M4 threaded rod cut to 195.9: from the mover crown's tapped hole down through both flexure stacks to 1 mm below the last hub nut.

## 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 |
|---|---|---|---|---|
| thread | M4 (drawn Ø4) | mover crown tap drill, hub nuts | designed | all |
| rod through the hubs | Ø4 | flexure hub Ø4, hub washer Ø4 | slide | all |

## Sizes

| thread | length_mm |
|---|---|
| M4 | 195.9 |

## Where the files are

- Xem Studio: [tools/gen_ta_power.py: the network model and every dimension on this page](https://xemstudio.com/) — code — CC BY 4.0
- 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/threaded-rods-metric/index.json

- rod-m4x195.9: [STEP](https://xemstudio.com/files/hardware/threaded-rods-metric/rod-m4x195.9.step) · [STL](https://xemstudio.com/files/hardware/threaded-rods-metric/rod-m4x195.9.stl) — M4 threaded rod × 195.9, thread as a plain Ø4 cylinder

## Questions

**Why threaded?**

The leaf hubs are clamped between nuts anywhere along it; no shoulders to machine.

## Fits with

- [Crankshafts Ø3, Ø5 and Ø8 with full-length D-flat](https://xemstudio.com/objects/stirling-crankshafts/)
- [Hex nuts, M2–M8 (ISO 4032)](https://xemstudio.com/objects/hex-nuts-metric/)
- [Tri-clamp flexure carrier: clamp-in 2 in, two Ø40 flexure stacks](https://xemstudio.com/objects/tri-clamp-flexure-carrier/)