# Universal joint for Ø5 shafts: Ø14 yokes and 8 mm cross spider

> How is a small universal joint for 5 mm shafts built?

- Category: Hardware › Motion
- Kind: Hardware
- Basis: Cardan joint: two yokes on Ø3 cross pins through an 8 × 8 spider; yoke arm gap equals the spider span
- Page: https://xemstudio.com/objects/universal-joint-5mm/ · JSON: https://xemstudio.com/api/geometry?object=universal-joint-5mm · Plain text: https://xemstudio.com/objects/universal-joint-5mm/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

- Two identical yokes (one file, make two) and one spider. Yoke: Ø14 × 8 hub with a Ø5 bore and a radial Ø2.5 (M3 tap drill) hole 4 mm up, two arms 3 thick × 5 wide rising to 16 overall, 8 mm apart, with a Ø3 cross hole 13 mm from the base.
- Spider: an 8 × 8 × 5 cross of 5 × 5 arms. One Ø3 hole runs straight through on one axis; the other axis has two Ø3 blind holes 2.5 deep, so two short pins stop clear of the through pin.
- The spider's 8 mm span fills the yokes' 8 mm arm gap. A single joint passes rotation through an angle with a once-per-half-turn speed ripple; two joints with their inner yokes in line cancel it.

## 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 |
|---|---|---|---|---|
| yoke bore | Ø5 | Ø5 shaft (M3 set screw) | slide | ujoint-yoke-* |
| set-screw hole | Ø2.5 | M3 tap drill | designed | ujoint-yoke-* |
| cross-pin holes | Ø3 | Ø3 pin (turns in it) | run | ujoint-yoke-* |
| arm gap | 8 | spider arm span 8 | run | ujoint-yoke-* |
| pin holes | Ø3 through + two Ø3 × 2.5 blind | one through pin, two short pins | press | ujoint-spider-* |
| arm span | 8 | yoke arm gap 8 | run | ujoint-spider-* |

## Sizes

| part | envelope | bore | cross holes | arm gap / span |
|---|---|---|---|---|
| ujoint-yoke-5mm | Ø14 × 16 | Ø5 + M3 tap Ø2.5 | Ø3 at 13 from base | 8 |
| ujoint-spider-14 | 8 × 8 × 5 | — | Ø3 through + 2 × Ø3 × 2.5 blind | 8 |

## 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 (2 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/universal-joint-5mm/index.json

- ujoint-yoke-5mm: [STEP](https://xemstudio.com/files/hardware/pins-clevises-and-joints/ujoint-yoke-5mm.step) · [STL](https://xemstudio.com/files/hardware/pins-clevises-and-joints/ujoint-yoke-5mm.stl) — universal joint yoke Ø14, Ø5 bore, M3 set screw (Ø2.5 tap drill), Ø3 cross-pin holes, 8 mm between the arms
- ujoint-spider-14: [STEP](https://xemstudio.com/files/hardware/pins-clevises-and-joints/ujoint-spider-14.step) · [STL](https://xemstudio.com/files/hardware/pins-clevises-and-joints/ujoint-spider-14.stl) — universal joint spider for the Ø14 yokes: 8 × 8 cross of 5 × 5 arms; Ø3 through hole for one pin, and two Ø3 blind holes 2.5 deep at 90° for short pins that stop clear of it

## How it fits

### Goes in or on
- [Metric shafts Ø3 to Ø10 with D-flats and clip grooves](https://xemstudio.com/objects/metric-shafts/): Ø5 shaft in the yoke bore

### Alternatives
- [Flexible shaft couplers, 5–10 mm bores](https://xemstudio.com/objects/shaft-couplers/): in-line shafts

### Also needed
- [Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)](https://xemstudio.com/objects/dowel-pins-metric/): Ø3 cross pins
- [Set screws (grub screws), M3–M8 (ISO 4026)](https://xemstudio.com/objects/set-screws-metric/): M3 grub in the yoke

## Questions

**What size is the universal joint?**

Yokes Ø14 × 16 tall on Ø5 shafts, spider 8 × 8 × 5, Ø3 cross pins; assembled it spans two yokes plus the spider.

**Why does the spider have blind holes?**

One Ø3 pin goes straight through on one axis; the crossing axis takes two short pins in 2.5 mm blind holes so they stop clear of it.

## Fits with

- [Flexible shaft couplers, 5–10 mm bores](https://xemstudio.com/objects/shaft-couplers/)
- [Clevis pins ISO 2341 B, Ø3 to Ø8](https://xemstudio.com/objects/clevis-pins/)
- [Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)](https://xemstudio.com/objects/dowel-pins-metric/)
- [Metric shafts Ø3 to Ø10 with D-flats and clip grooves](https://xemstudio.com/objects/metric-shafts/)
- [Set screws (grub screws), M3–M8 (ISO 4026)](https://xemstudio.com/objects/set-screws-metric/)