# Hose barbs for 2, 3, 4, 6 and 8 mm ID tube

> What barb size for 4 mm ID silicone tube?

- Category: Hardware › Pipe & fittings
- Kind: Hardware
- Basis: Barb geometry rule: shank Ø = tube ID, three 2.5 mm ramps to tube ID + 1.2 (the designed stretch), hex base AF = ID + 6
- Page: https://xemstudio.com/objects/hose-barbs/ · JSON: https://xemstudio.com/api/geometry?object=hose-barbs · Plain text: https://xemstudio.com/objects/hose-barbs/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

- Each barb has a 14 mm shank at the tube ID, three ridges (at 2, 6 and 10 mm from the tip) that ramp over 2.5 mm from the ID to ID + 1.2, and a 4 mm hex base; overall 18 mm.
- Sizes: 2 mm (ridges Ø3.2, Ø1 bore, 8 AF), 3 mm (Ø4.2, Ø1.5, 9 AF), 4 mm (Ø5.2, Ø2.5, 10 AF), 6 mm (Ø7.2, Ø4.5, 12 AF), 8 mm (Ø9.2, Ø6.5, 14 AF).
- The +1.2 on the ridges is the designed stretch of the tube; the shank is the tube ID, exact.
- The can-engine cap's transfer port is an integral Ø4 barb with the same profile as barb-4mm.

## 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 |
|---|---|---|---|---|
| barb shank | Ø = tube ID (2 / 3 / 4 / 6 / 8) | silicone tube ID | designed | barb-* |
| barb ridges | tube ID + 1.2 | silicone tube (stretched) | designed | barb-* |

## Sizes

| barb | shank_mm | ridge_mm | bore_mm | hex_af_mm |
|---|---|---|---|---|
| barb-2mm | 2 | 3.2 | 1 | 8 |
| barb-3mm | 3 | 4.2 | 1.5 | 9 |
| barb-4mm | 4 | 5.2 | 2.5 | 10 |
| barb-6mm | 6 | 7.2 | 4.5 | 12 |
| barb-8mm | 8 | 9.2 | 6.5 | 14 |

## Where the files are

- Wikipedia: [Hose barb](https://en.wikipedia.org/wiki/Hose_barb) — web — CC BY-SA 4.0 (text)
- Wikipedia: [Push-fit fitting](https://en.wikipedia.org/wiki/Push-to-connect_fitting) — web — CC BY-SA 4.0 (text)
- McMaster-Carr: [Tubing (free STEP per part, for your own design use; no redistribution)](https://www.mcmaster.com/products/tubing/) — 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/hose-barbs/index.json

- barb-2mm: [STEP](https://xemstudio.com/files/hardware/silicone-tube-and-fittings/barb-2mm.step) · [STL](https://xemstudio.com/files/hardware/silicone-tube-and-fittings/barb-2mm.stl) — hose barb for 2 mm ID tube: Ø2 shank, three barbs to Ø3.2, Ø1 bore, 8 AF hex base
- barb-3mm: [STEP](https://xemstudio.com/files/hardware/silicone-tube-and-fittings/barb-3mm.step) · [STL](https://xemstudio.com/files/hardware/silicone-tube-and-fittings/barb-3mm.stl) — hose barb for 3 mm ID tube: Ø3 shank, three barbs to Ø4.2, Ø1.5 bore, 9 AF hex base
- barb-4mm: [STEP](https://xemstudio.com/files/hardware/silicone-tube-and-fittings/barb-4mm.step) · [STL](https://xemstudio.com/files/hardware/silicone-tube-and-fittings/barb-4mm.stl) — hose barb for 4 mm ID tube: Ø4 shank, three barbs to Ø5.2, Ø2.5 bore, 10 AF hex base
- barb-6mm: [STEP](https://xemstudio.com/files/hardware/silicone-tube-and-fittings/barb-6mm.step) · [STL](https://xemstudio.com/files/hardware/silicone-tube-and-fittings/barb-6mm.stl) — hose barb for 6 mm ID tube: Ø6 shank, three barbs to Ø7.2, Ø4.5 bore, 12 AF hex base
- barb-8mm: [STEP](https://xemstudio.com/files/hardware/silicone-tube-and-fittings/barb-8mm.step) · [STL](https://xemstudio.com/files/hardware/silicone-tube-and-fittings/barb-8mm.stl) — hose barb for 8 mm ID tube: Ø8 shank, three barbs to Ø9.2, Ø6.5 bore, 14 AF hex base

## How it fits

### Goes in or on
- [Can-engine cap for 53.3, 58, 66 and 76.2 mm cans](https://xemstudio.com/objects/can-engine-cap/): the cap's integral Ø4 barb uses this profile

### Connects to
- [Silicone tube 1 × 3 to 10 × 14 mm (ID × OD)](https://xemstudio.com/objects/silicone-tube/): tube ID over the shank, stretched over the ID + 1.2 ridges

### Alternatives
- [Push-fit fitting envelopes: 4 / 6 / 8 mm tube, G1/8 and G1/4 thread stubs](https://xemstudio.com/objects/push-fit-fittings/): for stiff PU tube

### Also needed
- [Zip tie (cable tie) 4.8 × 1.3 mm cross-section](https://xemstudio.com/objects/zip-ties/): clamp over the tube on the barb

## Questions

**What barb size for 6 mm ID silicone tube?**

A Ø6 shank with ridges to Ø7.2 (ID + 1.2), three ridges 2.5 mm long; that is barb-6mm.

**How long is the barb?**

18 mm overall: a 14 mm barbed shank plus a 4 mm hex base.

**What is the bore of the 4 mm barb?**

Ø2.5 through, with ridges to Ø5.2 and a 10 mm AF hex.

## Fits with

- [Silicone tube 1 × 3 to 10 × 14 mm (ID × OD)](https://xemstudio.com/objects/silicone-tube/)
- [Push-fit fitting envelopes: 4 / 6 / 8 mm tube, G1/8 and G1/4 thread stubs](https://xemstudio.com/objects/push-fit-fittings/)
- [Can-engine cap for 53.3, 58, 66 and 76.2 mm cans](https://xemstudio.com/objects/can-engine-cap/)
- [Zip tie (cable tie) 4.8 × 1.3 mm cross-section](https://xemstudio.com/objects/zip-ties/)