# Print-in-place: barrel hinge, three knuckles, folds 180° (48.8 mm)

> How do you 3D print a hinge already assembled?

- Category: 3D printing › Print-in-place mechanisms
- Kind: Hardware
- Basis: Xem Studio design: 45° cone pivots on a horizontal axis; one designed running gap of 0.40 mm
- Page: https://xemstudio.com/objects/print-in-place-barrel-hinge-180/ · JSON: https://xemstudio.com/api/geometry?object=print-in-place-barrel-hinge-180 · Plain text: https://xemstudio.com/objects/print-in-place-barrel-hinge-180/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files Xem Studio Design License (free to use and sell from, not to redistribute as files: https://xemstudio.com/license/)
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

## Overall (mm)

| length | width | height |
|---|---|---|
| 48.8 | 70.0 | 10.0 |

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- 3D print in place — prints already assembled, moving, in one job. Drawn at true size with no printer tolerance added; the 0.40 mm running gaps are part of the design.
- Running gap 0.40 mm per side, 0.80 mm on diameter — part of the design, drawn as is. On the 45° faces the same 0.40 mm is measured square to the face (0.57 mm along the axis).
- Bed: opened flat, both leaves on the bed, the barrel axis horizontal 5 mm up. Each knuckle stands on a flat foot: below 45° the barrel's round is replaced by 45° tangents down to the bed.
- Support while printing: the pivots are 45° cones on the axis (the outer knuckles' cones point into sockets in the centre knuckle), and a 45° cone on a horizontal axis never overhangs more than 45°. Leaves and barrels print as plain walls.
- Captured by the two opposed cones: the centre knuckle sits between them, so it can neither slide along the axis nor drop out.
- Freeing it: hold leaf A flat and lift leaf B slowly to 90°, back, then all the way over to 180°; repeat a few times.
- Motion: leaf B folds 181.2° up from flat — over 180°, where the leaves lie face to face 0.8 mm apart — and 98.4° the other way; the stops are leaf on leaf (computed by turning the model).

## Sizes

| key | value | what |
|---|---|---|
| gap_mm | 0.4 | running gap per side on every moving interface (radial, axial, under captured parts) — part of the design, not a tolerance |
| hinge_l_mm | 48.8 | length along the axis |
| leaf_w_mm | 35.0 | each leaf, from the axis |
| leaf_t_mm | 4.6 | leaf thickness |
| knuckle_d_mm | 10.0 | knuckle (barrel) diameter |
| axis_h_mm | 5.0 | axis height above the bed |
| knuckles | 3 (12 + 24 + 12) | outer two on leaf A, centre one on leaf B |
| pin_d_mm | 6.0 | 45° cone pivot, base diameter (one each end of the centre knuckle) |
| socket_d_mm | 6.33 | cone socket at the knuckle face |
| fold_up_deg | 181.2 | leaf B about the axis, from flat (drawn) to the stop |
| fold_down_deg | 98.4 | the other way, from flat |
| gap_folded_mm | 0.8 | between the leaves' faces at 180° |
| mount_holes | 2 × Ø4.5 per leaf |  |

## Where the files are

- Xem Studio: [Print-in-place mechanism design (geometry computed in the generator)](https://xemstudio.com/) — web — Xem Studio design

## Free STEP/STL (3 parts, Xem Studio Design License, Xem Studio)

Index: https://xemstudio.com/files/hardware/print-in-place-barrel-hinge-180/index.json · license: https://xemstudio.com/files/hardware/print-in-place-barrel-hinge-180/LICENSE.md

- print-in-place-barrel-hinge-180-assembly: [STEP](https://xemstudio.com/files/hardware/print-in-place-barrel-hinge-180/print-in-place-barrel-hinge-180-assembly.step) · [STL](https://xemstudio.com/files/hardware/print-in-place-barrel-hinge-180/print-in-place-barrel-hinge-180-assembly.stl) — The whole print as laid on the bed (2 bodies, already assembled); STEP keeps each moving body a separate solid
- print-in-place-barrel-hinge-180-leaf-a: [STEP](https://xemstudio.com/files/hardware/print-in-place-barrel-hinge-180/print-in-place-barrel-hinge-180-leaf-a.step) · [STL](https://xemstudio.com/files/hardware/print-in-place-barrel-hinge-180/print-in-place-barrel-hinge-180-leaf-a.stl) — Leaf A with the two outer knuckles and the two 45° cone pivots
- print-in-place-barrel-hinge-180-leaf-b: [STEP](https://xemstudio.com/files/hardware/print-in-place-barrel-hinge-180/print-in-place-barrel-hinge-180-leaf-b.step) · [STL](https://xemstudio.com/files/hardware/print-in-place-barrel-hinge-180/print-in-place-barrel-hinge-180-leaf-b.stl) — Leaf B with the centre knuckle and its two cone sockets

## Questions

**What is the pin of a print-in-place hinge?**

There is no separate pin: each outer knuckle carries a 45° cone (Ø6 base) that runs in a cone socket of the centre knuckle, 0.40 mm clear square to the cone.

**Does it fold flat?**

Yes: at 180° the leaves lie face to face, 0.8 mm apart; the knuckles are 10 mm in diameter on 4.6 mm leaves.

## Fits with

- [Print-in-place: captive wheel on a printed axle (Ø40 × 12)](https://xemstudio.com/objects/print-in-place-captive-wheel-axle/)
- [Print-in-place: seven-knuckle hinge on a captive through-pin (58.4 mm)](https://xemstudio.com/objects/print-in-place-multi-knuckle-hinge/)
- [Print-in-place: captive turntable with V-ridge retention (Ø80 platter)](https://xemstudio.com/objects/print-in-place-captive-turntable/)
- [Print-in-place: linear slider on a dovetail rail with end stops (100 mm)](https://xemstudio.com/objects/print-in-place-dovetail-slider/)
- [Print-in-place: articulated chain, 6 links, 20 mm pitch](https://xemstudio.com/objects/print-in-place-articulated-chain/)
- [Print-in-place: captive ball joint, Ø24 ball, limited cone](https://xemstudio.com/objects/print-in-place-ball-joint/)
- [Print-in-place: push button with flexure return and click](https://xemstudio.com/objects/print-in-place-push-button-flexure/)