# Rod ends (heim joints) M3 to M8

> What are the dimensions of M3–M8 rod ends?

- Category: Hardware › Motion
- Kind: Hardware
- Basis: POS-series male rod-end envelopes: ball Ø 2 × M, head OD ball + 4, head thickness 0.8 × ball
- Page: https://xemstudio.com/objects/rod-ends-heim-joints/ · JSON: https://xemstudio.com/api/geometry?object=rod-ends-heim-joints · Plain text: https://xemstudio.com/objects/rod-ends-heim-joints/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

- Envelope of a male rod end: a ball with a bore of the thread size, held in a head of OD ball + 4 and thickness 0.8 × ball, on a threaded shank drawn at the thread major Ø.
- Ball Ø: M3 6, M4 8, M5 10, M6 12, M8 16. Ball centre to shank end: 20, 24, 28, 32 and 42 mm.
- The ball's bore is the thread Ø (3–8) and takes a bolt of that size; ±13° of misalignment is the catalogue figure for this series.

## 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 |
|---|---|---|---|---|
| ball bore | Ø3–Ø8 (= M) | bolt of the same Ø | slide | rod-end-* |

## Sizes

| file | thread | ball bore | ball Ø | head OD × thickness | centre to shank end |
|---|---|---|---|---|---|
| rod-end-m3 | M3 | 3 | 6 | 10 × 4.8 | 20 |
| rod-end-m4 | M4 | 4 | 8 | 12 × 6.4 | 24 |
| rod-end-m5 | M5 | 5 | 10 | 14 × 8 | 28 |
| rod-end-m6 | M6 | 6 | 12 | 16 × 9.6 | 32 |
| rod-end-m8 | M8 | 8 | 16 | 20 × 12.8 | 42 |

## Where the files are

- Wikipedia: [Clevis fastener](https://en.wikipedia.org/wiki/Clevis_fastener) — web — CC BY-SA 4.0 (text)
- Wikipedia: [Universal joint](https://en.wikipedia.org/wiki/Universal_joint) — web — CC BY-SA 4.0 (text)
- Wikipedia: [Rod end bearing](https://en.wikipedia.org/wiki/Rod_end_bearing) — web — CC BY-SA 4.0 (text)
- McMaster-Carr: [Clevis pins (free STEP per part, for your own design use; no redistribution)](https://www.mcmaster.com/products/clevis-pins/) — STEP, PDF — McMaster-Carr site terms (verify at link)
- McMaster-Carr: [Rod ends (free STEP per part, for your own design use; no redistribution)](https://www.mcmaster.com/products/ball-joint-rod-ends/) — STEP, PDF — McMaster-Carr site terms (verify at link)
- Long Earth Society: [Engine and rig builds](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/rod-ends-heim-joints/index.json

- rod-end-m3: [STEP](https://xemstudio.com/files/hardware/pins-clevises-and-joints/rod-end-m3.step) · [STL](https://xemstudio.com/files/hardware/pins-clevises-and-joints/rod-end-m3.stl) — rod end (heim joint) envelope M3: ball bore 3, ball Ø6, head OD ball + 4
- rod-end-m4: [STEP](https://xemstudio.com/files/hardware/pins-clevises-and-joints/rod-end-m4.step) · [STL](https://xemstudio.com/files/hardware/pins-clevises-and-joints/rod-end-m4.stl) — rod end (heim joint) envelope M4: ball bore 4, ball Ø8, head OD ball + 4
- rod-end-m5: [STEP](https://xemstudio.com/files/hardware/pins-clevises-and-joints/rod-end-m5.step) · [STL](https://xemstudio.com/files/hardware/pins-clevises-and-joints/rod-end-m5.stl) — rod end (heim joint) envelope M5: ball bore 5, ball Ø10, head OD ball + 4
- rod-end-m6: [STEP](https://xemstudio.com/files/hardware/pins-clevises-and-joints/rod-end-m6.step) · [STL](https://xemstudio.com/files/hardware/pins-clevises-and-joints/rod-end-m6.stl) — rod end (heim joint) envelope M6: ball bore 6, ball Ø12, head OD ball + 4
- rod-end-m8: [STEP](https://xemstudio.com/files/hardware/pins-clevises-and-joints/rod-end-m8.step) · [STL](https://xemstudio.com/files/hardware/pins-clevises-and-joints/rod-end-m8.stl) — rod end (heim joint) envelope M8: ball bore 8, ball Ø16, head OD ball + 4

## How it fits

### Connects to
- [Four-bar links: flat links with 20 to 100 mm hole centres](https://xemstudio.com/objects/four-bar-links/): bolt through the ball into the link
- [Bell cranks: 30 × 30 and 20 × 40 mm arms at 90°](https://xemstudio.com/objects/bell-cranks/): bolt through the ball at the crank arm

### Alternatives
- [Clevises with M3 tapped shank: Ø3, Ø5 and Ø6 pins, 5 to 12 mm gaps](https://xemstudio.com/objects/clevises/): fork and pin instead of a ball

## Questions

**What are M5 rod end dimensions?**

Ball bore 5, ball Ø10, head Ø14 × 8 thick, 28 mm from the ball centre to the end of the M5 shank.

**What bolt goes through a rod end?**

One of the thread size: the M6 rod end's ball has a Ø6 bore.

## Fits with

- [Clevises with M3 tapped shank: Ø3, Ø5 and Ø6 pins, 5 to 12 mm gaps](https://xemstudio.com/objects/clevises/)
- [Clevis pins ISO 2341 B, Ø3 to Ø8](https://xemstudio.com/objects/clevis-pins/)
- [Four-bar links: flat links with 20 to 100 mm hole centres](https://xemstudio.com/objects/four-bar-links/)
- [Bell cranks: 30 × 30 and 20 × 40 mm arms at 90°](https://xemstudio.com/objects/bell-cranks/)