# Displacer rods Ø2 × 60, 78, 100 and 180, Ø3 × 100, 150 and 200

> What size rod connects a Stirling displacer to its crank?

- Category: Stirling engines › Drives & mechanisms
- Kind: Hardware
- Basis: Solid rods at the bore Ø of the parts they pass through: Ø3 for the tri-clamp heads, Ø2 for the can-engine cap and LTD top plate
- Page: https://xemstudio.com/objects/displacer-rods/ · JSON: https://xemstudio.com/api/geometry?object=displacer-rods · Plain text: https://xemstudio.com/objects/displacer-rods/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

- Solid rods with 0.3 chamfers at both ends, plain round, no flat: Ø3 × 100, 150 and 200, and Ø2 × 60, 78, 100 and 180.
- On the tri-clamp engines the rod runs from the displacer cap's socket (M3 grub) up through the head's Ø3 bore, which is its guide and seal, to the rod clevis.
- Rod length = displacer cap to clevis plus the stroke.
- On the can engine and the LTD engines the Ø2 rod runs through the Ø2 bore in the can cap or the LTD top plate, from the displacer (flush with its underside) to the rod-clevis-2mm: 180 on the can engine, 76 on the Ø100 LTD.
- On the rhombic and free-piston engines the same Ø3 rod runs up the inside of the Ø5 tube piston rod (Ø3.4 bore).

## 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 |
|---|---|---|---|---|
| shafts, rods, pins | Ø3 / Ø5 / Ø8 | the bores listed on each mating object | slide | all |

## Sizes

| file | Ø | length |
|---|---|---|
| rod-2x60 | 2 | 60 |
| rod-2x76 | 2 | 78 |
| rod-2x100 | 2 | 100 |
| rod-2x180 | 2 | 180 |
| rod-3x100 | 3 | 100 |
| rod-3x150 | 3 | 150 |
| rod-3x200 | 3 | 200 |

## Where the files are

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

## Free STEP/STL (7 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/displacer-rods/index.json

- rod-3x100: [STEP](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-3x100.step) · [STL](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-3x100.stl) — Ø3 × 100 solid rod: displacer rod (into the displacer cap's grub, through the head's Ø3 bore and the piston crown, into the rod clevis)
- rod-3x150: [STEP](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-3x150.step) · [STL](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-3x150.stl) — Ø3 × 150 solid rod: displacer rod (into the displacer cap's grub, through the head's Ø3 bore and the piston crown, into the rod clevis)
- rod-3x200: [STEP](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-3x200.step) · [STL](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-3x200.stl) — Ø3 × 200 solid rod: displacer rod (into the displacer cap's grub, through the head's Ø3 bore and the piston crown, into the rod clevis)
- rod-2x60: [STEP](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x60.step) · [STL](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x60.stl) — Ø2 × 60 solid rod: displacer rod for the can and LTD engines (through the Ø2 bore in the can cap or LTD top plate; 76 is the LTD's, 180 the can engine's, displacer to rod clevis)
- rod-2x76: [STEP](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x76.step) · [STL](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x76.stl) — Ø2 × 76 solid rod: displacer rod for the can and LTD engines (through the Ø2 bore in the can cap or LTD top plate; 76 is the LTD's, 180 the can engine's, displacer to rod clevis)
- rod-2x100: [STEP](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x100.step) · [STL](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x100.stl) — Ø2 × 100 solid rod: displacer rod for the can and LTD engines (through the Ø2 bore in the can cap or LTD top plate; 76 is the LTD's, 180 the can engine's, displacer to rod clevis)
- rod-2x180: [STEP](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x180.step) · [STL](https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x180.stl) — Ø2 × 180 solid rod: displacer rod for the can and LTD engines (through the Ø2 bore in the can cap or LTD top plate; 76 is the LTD's, 180 the can engine's, displacer to rod clevis)

## How it fits

### Goes in or on
- [Tri-clamp displacer: Ø33.6, Ø46 and Ø70.9 for 1.5, 2 and 3 in spools](https://xemstudio.com/objects/tri-clamp-displacer/): Ø3 rod in the displacer cap socket and the head's Ø3 bore
- [Tube piston rods Ø5 × Ø3.4](https://xemstudio.com/objects/tube-piston-rods-5mm/): runs inside the Ø3.4 bore
- [Can-engine cap for 53.3, 58, 66 and 76.2 mm cans](https://xemstudio.com/objects/can-engine-cap/): Ø2 rod in the cap's Ø2 bore
- [LTD Stirling top plate with syringe socket, Ø120 and Ø170](https://xemstudio.com/objects/ltd-top-plate/): Ø2 rod in the top plate's Ø2 bore

### Connects to
- [Rod clevises for a Ø2 or Ø3 rod or a Ø5 tube, 5 mm gap](https://xemstudio.com/objects/rod-clevises/): Ø3 socket with M3 grub

## Questions

**What diameter is the displacer rod?**

Ø3 on the tri-clamp engines, where it slides in the head's Ø3 bore and seats in the displacer cap and rod clevis sockets. Ø2 on the can engine and LTD engines, through the Ø2 bore in the cap or top plate.

**How long should the displacer rod be?**

Displacer cap to rod clevis plus the stroke; the files are 100, 150 and 200 long.

## Fits with

- [Rod clevises for a Ø2 or Ø3 rod or a Ø5 tube, 5 mm gap](https://xemstudio.com/objects/rod-clevises/)
- [Tri-clamp displacer: Ø33.6, Ø46 and Ø70.9 for 1.5, 2 and 3 in spools](https://xemstudio.com/objects/tri-clamp-displacer/)
- [Tube piston rods Ø5 × Ø3.4](https://xemstudio.com/objects/tube-piston-rods-5mm/)
- [Crankshafts Ø3, Ø5 and Ø8 with full-length D-flat](https://xemstudio.com/objects/stirling-crankshafts/)
- [Can-engine cap for 53.3, 58, 66 and 76.2 mm cans](https://xemstudio.com/objects/can-engine-cap/)
- [LTD Stirling top plate with syringe socket, Ø120 and Ø170](https://xemstudio.com/objects/ltd-top-plate/)