# Print-in-place: seven-knuckle hinge on a captive through-pin (58.4 mm)

> How do you 3D print a piano-style hinge with the pin already in?

- Category: 3D printing › Print-in-place mechanisms
- Kind: Hardware
- Basis: Xem Studio design: horizontal through-pin, teardrop bores; one designed running gap of 0.40 mm
- Page: https://xemstudio.com/objects/print-in-place-multi-knuckle-hinge/ · JSON: https://xemstudio.com/api/geometry?object=print-in-place-multi-knuckle-hinge · Plain text: https://xemstudio.com/objects/print-in-place-multi-knuckle-hinge/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 |
|---|---|---|
| 58.4 | 60.0 | 9.0 |

**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, axis horizontal 4.5 mm up; every knuckle stands on its 45° foot.
- Support while printing: the Ø3.6 pin belongs to leaf A and runs straight through all seven knuckles; across each leaf-B knuckle it is a 8.8 mm bridge between two leaf-A knuckles. The leaf-B bores have a 45° peaked roof (teardrop), so no ceiling is flat.
- Captured: the pin passes through every leaf-B knuckle and leaf A's knuckles close both ends, so leaf B cannot come off the pin or slide along it.
- Freeing it: hold leaf A and swing leaf B through its range a few times; the bridge layers under the pin may need one firm first turn.
- Motion: leaf B folds 183.3° up from flat (past 180°, face to face) and 98.9° down; stops are leaf on leaf (computed).

## 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 | 58.4 | length along the axis |
| knuckles | 7 × 8 mm | 4 on leaf A (both ends), 3 on leaf B |
| knuckle_d_mm | 9.0 |  |
| pin_d_mm | 3.6 | through-pin, part of leaf A, runs the whole length |
| bore_d_mm | 4.4 | leaf B knuckle bore, with a 45° peaked roof |
| leaf_w_mm | 30.0 | each leaf, from the axis |
| leaf_t_mm | 3.6 |  |
| axis_h_mm | 4.5 |  |
| bridge_mm | 8.8 | pin span between leaf A knuckles (printed as a bridge) |
| fold_up_deg | 183.3 | leaf B from flat to the stop |
| fold_down_deg | 98.9 | the other way |
| mount_holes | 3 × Ø3.4 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-multi-knuckle-hinge/index.json · license: https://xemstudio.com/files/hardware/print-in-place-multi-knuckle-hinge/LICENSE.md

- print-in-place-multi-knuckle-hinge-assembly: [STEP](https://xemstudio.com/files/hardware/print-in-place-multi-knuckle-hinge/print-in-place-multi-knuckle-hinge-assembly.step) · [STL](https://xemstudio.com/files/hardware/print-in-place-multi-knuckle-hinge/print-in-place-multi-knuckle-hinge-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-multi-knuckle-hinge-leaf-a: [STEP](https://xemstudio.com/files/hardware/print-in-place-multi-knuckle-hinge/print-in-place-multi-knuckle-hinge-leaf-a.step) · [STL](https://xemstudio.com/files/hardware/print-in-place-multi-knuckle-hinge/print-in-place-multi-knuckle-hinge-leaf-a.stl) — Leaf A: four knuckles and the Ø3.6 through-pin
- print-in-place-multi-knuckle-hinge-leaf-b: [STEP](https://xemstudio.com/files/hardware/print-in-place-multi-knuckle-hinge/print-in-place-multi-knuckle-hinge-leaf-b.step) · [STL](https://xemstudio.com/files/hardware/print-in-place-multi-knuckle-hinge/print-in-place-multi-knuckle-hinge-leaf-b.stl) — Leaf B: three knuckles with teardrop bores

## Questions

**Is the pin a separate part?**

No — it is part of leaf A and prints with it; leaf B's knuckles print around it with 0.40 mm all round (bore Ø4.4 on a Ø3.6 pin).

**Why are the bores pointed at the top?**

A round horizontal hole has a flat ceiling at the top; the 45° peak lets it print without support. The pin never reaches the peak.

## 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: barrel hinge, three knuckles, folds 180° (48.8 mm)](https://xemstudio.com/objects/print-in-place-barrel-hinge-180/)
- [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/)