# HTD crank and linkage: webs, link web, con-rods, clevis and Ø12 shafts for a 3 in cross crankcase

> How is the crank of the 10 in HTD engine laid out?

- Category: Stirling engines › Tri-clamp engine parts
- Kind: Hardware
- Basis: Exact geometry; designed running gaps between every moving plane
- Page: https://xemstudio.com/objects/htd-crank-linkage/ · JSON: https://xemstudio.com/api/geometry?object=htd-crank-linkage · Plain text: https://xemstudio.com/objects/htd-crank-linkage/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

- Built-up crank on Ø12 shafts in 6001 bearings: web A (displacer throw r 4) – Ø5 pin through the displacer con-rod's 625 – link web – Ø5 pin through the piston con-rod's 625 – web C (piston throw r 20). The displacer pin leads the piston pin by 90°.
- Planes along the shaft (x): web A disc −9.5..−3.5, displacer con-rod −2.5..2.5, link web 3.5..9.5, piston con-rod 10.5..15.5, web C 16.5..22.5: 1.0 between every rod and web (designed). Pins are Ø5 × 16 dowels pressed in the webs.
- Con-rods 60 (displacer, to the clevis on the rod) and 237 (piston, down through the reducer to the piston's cheeks); every eye runs on a 625. Sweep radius 31 (piston eye) inside the 3 in cross bore Ø72.9.

## 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 |
|---|---|---|---|---|
| web and hub bores | Ø12 | Ø12 shafts (M4 grub on each hub) | slide | crank-web-* |
| pin bores | Ø5 | dowel-5x16 crank pins | press | crank-web-* |
| con-rod pockets | Ø16 × 5 | bearing-625 outer ring | press | conrod-* |
| clevis socket | Ø6 × 14 | displacer rod, M4 grub | slide | rod-clevis-* |
| clevis slot and pin | 6.0 wide, Ø5 | 5 thick con-rod; dowel-5x16 | press | rod-clevis-* |
| plane gaps | 1.0 between every web and con-rod plane | neighbouring webs and rods | designed | all |
| shafts | Ø12 | bearing-6001 inner rings | press | shaft-* |

## Sizes

| part | role | size |
|---|---|---|
| crank-web-r8-b12 | displacer web | r 4 |
| crank-web-link-r8-r20 | link web | r 4 / 20 |
| crank-web-r20-b12 | piston web | r 20 |
| conrod-60-625 | con-rod | 60.0 |
| conrod-237-625 | con-rod | 237.0 |
| rod-clevis-6-pin5 | rod clevis | Ø6 rod, Ø5 pin |
| shaft-12x76 | shaft | 76 |
| shaft-12x210 | shaft | 210 |

## Where the files are

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

## Free STEP/STL (8 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/htd-crank-linkage/index.json

- crank-web-r8-b12: [STEP](https://xemstudio.com/files/hardware/htd-crank-linkage/crank-web-r8-b12.step) · [STL](https://xemstudio.com/files/hardware/htd-crank-linkage/crank-web-r8-b12.stl) — crank web, hub type: disc R12 × 6 with a Ø5 pin at r 4 (8 displacer stroke), hub Ø24 × 8, Ø12 bore in the hub only, M4 tapped radial hole
- crank-web-link-r8-r20: [STEP](https://xemstudio.com/files/hardware/htd-crank-linkage/crank-web-link-r8-r20.step) · [STL](https://xemstudio.com/files/hardware/htd-crank-linkage/crank-web-link-r8-r20.stl) — link web 6 thick: Ø5 displacer pin at r 4 and Ø5 piston pin at r 20, 90° apart
- crank-web-r20-b12: [STEP](https://xemstudio.com/files/hardware/htd-crank-linkage/crank-web-r20-b12.step) · [STL](https://xemstudio.com/files/hardware/htd-crank-linkage/crank-web-r20-b12.stl) — crank web, hub type: disc R28 × 6 with a Ø5 pin at r 20 (40 piston stroke), hub Ø24 × 8, Ø12 bore through, M4 tapped radial hole
- conrod-60-625: [STEP](https://xemstudio.com/files/hardware/htd-crank-linkage/conrod-60-625.step) · [STL](https://xemstudio.com/files/hardware/htd-crank-linkage/conrod-60-625.stl) — con-rod 60 centres, 5 thick, Ø16 pockets for 625 bearings, eyes Ø22
- conrod-237-625: [STEP](https://xemstudio.com/files/hardware/htd-crank-linkage/conrod-237-625.step) · [STL](https://xemstudio.com/files/hardware/htd-crank-linkage/conrod-237-625.stl) — con-rod 237 centres, 5 thick, Ø16 pockets for 625 bearings, eyes Ø22
- rod-clevis-6-pin5: [STEP](https://xemstudio.com/files/hardware/htd-crank-linkage/rod-clevis-6-pin5.step) · [STL](https://xemstudio.com/files/hardware/htd-crank-linkage/rod-clevis-6-pin5.stl) — rod clevis: 13 × 14 × 41 block, slot 6 wide for a 5 con-rod, Ø5 pin bore, Ø6 rod socket 14 deep, M4 tapped radial hole
- shaft-12x76: [STEP](https://xemstudio.com/files/hardware/htd-crank-linkage/shaft-12x76.step) · [STL](https://xemstudio.com/files/hardware/htd-crank-linkage/shaft-12x76.stl) — Ø12 × 76 crankshaft, −X (main): blind-cap 6001 to web A's hub
- shaft-12x210: [STEP](https://xemstudio.com/files/hardware/htd-crank-linkage/shaft-12x210.step) · [STL](https://xemstudio.com/files/hardware/htd-crank-linkage/shaft-12x210.stl) — Ø12 × 210 crankshaft, +X: web C, two 6001, the seal, gear and flywheel

## Questions

**Why a built-up crank?**

One-piece con-rod eyes on 625 bearings slide onto the pins before the webs close up; nothing has to be split.

## Fits with

- [Build list: HTD engine, 10 in tri-clamp (high-temperature-differential flat engine)](https://xemstudio.com/objects/list-htd-10in/)
- [3 in crankcase caps: blind bearing cap, seal cap and 3-port cap](https://xemstudio.com/objects/htd-crankcase-caps-3in/)
- [HTD power pistons: Ø48.00 × 72 for the bored 2 in spool](https://xemstudio.com/objects/htd-power-pistons/)
- [Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)](https://xemstudio.com/objects/dowel-pins-metric/)
- [Ball bearings, 683 to 6210 and flanged F6xx (ISO 15)](https://xemstudio.com/objects/ball-bearings-metric/)