# Rod clevises for a Ø2 or Ø3 rod or a Ø5 tube, 5 mm gap

> How does a plain 3 mm displacer rod connect to a connecting rod?

- Category: Stirling engines › Drives & mechanisms
- Kind: Hardware
- Basis: Clevis with a socket at the rod Ø, M3 grub, 5 mm gap for a 5 mm con-rod and a Ø3 cross pin 8 mm above the slot floor (a con-rod eye, R7, clears the floor by 1 mm)
- Page: https://xemstudio.com/objects/rod-clevises/ · JSON: https://xemstudio.com/api/geometry?object=rod-clevises · Plain text: https://xemstudio.com/objects/rod-clevises/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

- A fork 12 × 9 × 18 with a 5 mm gap (the con-rod thickness) between two 3.5 mm cheeks and a Ø3 cross hole 12 mm up; the slot floor is 4 mm up, 8 below the pin, so the con-rod's R7 eye swings 1 mm clear of it. A round socket below; overall 30 tall.
- Rod-clevis-2mm: Ø8 socket boss with a Ø2 bore for the can and LTD engines' displacer rod. rod-clevis-3mm: Ø9 socket boss with a Ø3 bore 16 deep for the displacer rod. rod-clevis-5mm-tube: Ø11 boss with a Ø5 bore for the tube piston rod. Socket wall 3 mm, so an M3 × 3 grub sits flush.
- A radial Ø2.5 hole (M3 tap drill) 6 mm below the fork locks the rod with a grub.
- The con-rod's 623 end sits in the gap on a Ø3 × 12 pin, the full width of the fork.

## 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 |
|---|---|---|---|---|
| rod-clevis socket | Ø2 / Ø3 / Ø5 | Ø2 rod / Ø3 rod / 5 mm tube (M3 grub) | slide | rod-clevis-* |
| rod-clevis pin hole | Ø3 | Ø3 pin; the con-rod turns on it | press | rod-clevis-* |
| rod-clevis gap | 5.0 | 5 mm con-rod, 623 end (turns in it) | run | rod-clevis-* |
| rod-clevis grub hole | Ø2.5 | M3 tap drill | designed | rod-clevis-* |
| rod-clevis slot floor | 8 below the pin | con-rod eye R7 (1 mm clear) | designed | rod-clevis-* |

## Sizes

| file | socket | boss | gap | pin hole | overall |
|---|---|---|---|---|---|
| rod-clevis-2mm | Ø2 × 16 | Ø7 | 5 | Ø3 | 11 × 9 × 26 |
| rod-clevis-3mm | Ø3 × 16 | Ø9 | 5 | Ø3 at 12, floor at 4 | 12 × 9 × 30 |
| rod-clevis-5mm-tube | Ø5 × 16 | Ø11 | 5 | Ø3 at 12, floor at 4 | 12 × 11 × 30 |

## Where the files are

- Long Earth Society: [Tri-clamp Stirling engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (3 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/rod-clevises/index.json

- rod-clevis-3mm: [STEP](https://xemstudio.com/files/hardware/stirling-linkage-fittings/rod-clevis-3mm.step) · [STL](https://xemstudio.com/files/hardware/stirling-linkage-fittings/rod-clevis-3mm.stl) — clevis for a Ø3 displacer or piston rod: Ø9 × 12 socket with a Ø3 bore and a tapped M3 grub (Ø2.5) 6 from its top, two 3.5 mm cheeks 5 apart (a 5 mm con-rod), Ø3 cross pin 12 above the socket, slot floor 8 below the pin; 12 × 9 × 18 above the socket: takes a con-rod's 623 end on a Ø3 × 12 pin
- rod-clevis-2mm: [STEP](https://xemstudio.com/files/hardware/stirling-linkage-fittings/rod-clevis-2mm.step) · [STL](https://xemstudio.com/files/hardware/stirling-linkage-fittings/rod-clevis-2mm.stl) — clevis for the Ø2 displacer rod of the can and LTD engines: Ø8 × 12 socket with a Ø2 bore and a tapped M3 grub (Ø2.5), cheeks and Ø3 pin as the 3 mm clevis
- rod-clevis-5mm-tube: [STEP](https://xemstudio.com/files/hardware/stirling-linkage-fittings/rod-clevis-5mm-tube.step) · [STL](https://xemstudio.com/files/hardware/stirling-linkage-fittings/rod-clevis-5mm-tube.stl) — clevis for the 5 mm tube piston rod: Ø11 × 12 socket with a Ø5 bore and a tapped M3 grub (Ø2.5), cheeks and Ø3 pin as the 3 mm clevis

## How it fits

### Parts that fit it
- [Crank and wrist pins Ø3 × 12, 16, 19, 20 and 23](https://xemstudio.com/objects/pins-3mm/): Ø3 hole across the 5 mm gap

### Goes in or on
- [Displacer rods Ø2 × 60, 78, 100 and 180, Ø3 × 100, 150 and 200](https://xemstudio.com/objects/displacer-rods/): Ø3 rod in the socket, M3 grub
- [Tube piston rods Ø5 × Ø3.4](https://xemstudio.com/objects/tube-piston-rods-5mm/): Ø5 tube in the 5mm-tube socket

### Connects to
- [Connecting rods 30 to 80 mm centres with 623 pockets](https://xemstudio.com/objects/connecting-rods-623/): 5 mm con-rod in the 5 mm gap

### Also needed
- [Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)](https://xemstudio.com/objects/dowel-pins-metric/): Ø3 × 12 pin across the fork
- [Set screws (grub screws), M3–M8 (ISO 4026)](https://xemstudio.com/objects/set-screws-metric/): M3 × 3 grub

## Questions

**How do I connect a 3 mm displacer rod to a connecting rod?**

Rod-clevis-3mm: the rod goes in the Ø3 socket under an M3 × 3 grub; the con-rod's 5 mm thick 623 end sits in the 5 mm gap on a Ø3 × 12 pin.

**What is the clevis for the tube piston rod?**

Rod-clevis-5mm-tube: same 5 mm gap and Ø3 pin, Ø5 socket for the tube.

## Fits with

- [Displacer rods Ø2 × 60, 78, 100 and 180, Ø3 × 100, 150 and 200](https://xemstudio.com/objects/displacer-rods/)
- [Tube piston rods Ø5 × Ø3.4](https://xemstudio.com/objects/tube-piston-rods-5mm/)
- [Connecting rods 30 to 80 mm centres with 623 pockets](https://xemstudio.com/objects/connecting-rods-623/)
- [Crank and wrist pins Ø3 × 12, 16, 19, 20 and 23](https://xemstudio.com/objects/pins-3mm/)
- [Clevises with M3 tapped shank: Ø3, Ø5 and Ø6 pins, 5 to 12 mm gaps](https://xemstudio.com/objects/clevises/)