# Camera tripod thread bosses: 1/4-20 UNC and 3/8-16 UNC

> What thread is a camera tripod screw?

- Category: Everyday mounts › Adapter blocks
- Kind: Hardware
- Basis: DIN 4503-1 / ISO 1222 tripod threads as given by Threading Tools Guide: 1/4-20 UNC (major Ø6.35, core hole Ø5.35) and 3/8-16 UNC (major Ø9.52, core hole Ø8.25)
- Page: https://xemstudio.com/objects/camera-thread-bosses-1-4-20/ · JSON: https://xemstudio.com/api/geometry?object=camera-thread-bosses-1-4-20 · Plain text: https://xemstudio.com/objects/camera-thread-bosses-1-4-20/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

- Cameras, phone clamps, lights and small tripod heads take a 1/4-20 UNC screw; larger heads and most tripod-to-head joints use 3/8-16 UNC. Both are 60° Unified threads.
- Files: a round boss for each with a blind hole at the published core-hole diameter, to cut the internal thread into or to fit a threaded insert of your choice. The boss Ø, height and hole depth are my design.
- The screw side is in the catalog: 1/4-20 socket head cap screws in imperial-machine-screws.
- Arca-Swiss style dovetails are not drawn: there is no published standard; makers' plates measure 38.0 to 38.75 mm across.

## 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 |
|---|---|---|---|---|
| core hole | Ø5.35 (1/4-20 UNC) / Ø8.25 (3/8-16 UNC) | internal thread cut to the screw (DIN 4503-1 / ISO 1222) | designed | camera-boss-* |

## Sizes

| thread | major Ø (mm) | core hole Ø (mm) | boss (my design) | from |
|---|---|---|---|---|
| 1/4-20 UNC | 6.35 | 5.35 | Ø16 × 10, hole 8 deep | DIN 4503-1 / ISO 1222 (Threading Tools Guide) |
| 3/8-16 UNC | 9.52 | 8.25 | Ø22 × 12, hole 10 deep | DIN 4503-1 / ISO 1222 (Threading Tools Guide) |

## Where the files are

- Threading Tools Guide: [Tripod thread DIN 4503-1 / ISO 1222: 1/4-20 UNC (Ø6.35, core hole Ø5.35) and 3/8-16 UNC (Ø9.52, core hole Ø8.25)](https://threadingtoolsguide.com/en/blog/tripod-thread-din-4503-1-iso-1222/) — web — reference (verify at link)

## Free STEP/STL (2 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/camera-thread-bosses-1-4-20/index.json

- camera-boss-1-4-20: [STEP](https://xemstudio.com/files/hardware/camera-thread-bosses-1-4-20/camera-boss-1-4-20.step) · [STL](https://xemstudio.com/files/hardware/camera-thread-bosses-1-4-20/camera-boss-1-4-20.stl) — 1/4-20 UNC boss: Ø16 × 10 (my size), blind core hole Ø5.35 × 8 deep from the top face for the 1/4-20 UNC internal thread (major Ø6.35)
- camera-boss-3-8-16: [STEP](https://xemstudio.com/files/hardware/camera-thread-bosses-1-4-20/camera-boss-3-8-16.step) · [STL](https://xemstudio.com/files/hardware/camera-thread-bosses-1-4-20/camera-boss-3-8-16.stl) — 3/8-16 UNC boss: Ø22 × 12 (my size), blind core hole Ø8.25 × 10 deep from the top face for the 3/8-16 UNC internal thread (major Ø9.52)

## How it fits

### Goes in or on
- [Handlebar clamp rings: split rings for 22.2 to 35.0 mm bars, M4 / M5](https://xemstudio.com/objects/handlebar-clamp-rings/): a boss unioned onto a bar clamp

### Connects to
- [Imperial machine screws: #4-40, #6-32, #8-32, 1/4-20](https://xemstudio.com/objects/imperial-machine-screws/): 1/4-20 screw into the boss

### Alternatives
- [GoPro-style three-finger mount](https://xemstudio.com/objects/gopro-mount/): three-finger action-camera mount

## Questions

**What thread is a camera tripod screw?**

1/4-20 UNC on cameras and small accessories, 3/8-16 UNC on larger heads and tripods (DIN 4503-1 / ISO 1222).

**What hole size for a 1/4-20 thread?**

Core hole Ø5.35 mm per DIN 4503-1 as given by Threading Tools Guide; the major diameter is 6.35 mm.

**Is there a standard Arca-Swiss plate drawing?**

No published standard; plates measure 38.0–38.75 mm across the dovetail, so none is drawn here.

## Fits with

- [Imperial machine screws: #4-40, #6-32, #8-32, 1/4-20](https://xemstudio.com/objects/imperial-machine-screws/)
- [Handlebar clamp rings: split rings for 22.2 to 35.0 mm bars, M4 / M5](https://xemstudio.com/objects/handlebar-clamp-rings/)
- [17 mm ball joint for phone mounts (ball stud)](https://xemstudio.com/objects/phone-mount-ball-17mm/)
- [GoPro-style three-finger mount](https://xemstudio.com/objects/gopro-mount/)