# Build list: Tri-clamp cross diaphragm gamma, 2 in

> What parts do I need to build a Tri-clamp cross diaphragm gamma, 2 in?

- Category: Stirling engines › Guide
- Kind: List / guide
- Basis: Every part is a free STEP/STL on this site or a standard part with its own page; quantities are the full count, every screw, nut, pin, gasket and clamp.
- Page: https://xemstudio.com/objects/list-tri-clamp-cross-diaphragm-gamma/ · JSON: https://xemstudio.com/api/geometry?object=list-tri-clamp-cross-diaphragm-gamma · Plain text: https://xemstudio.com/objects/list-tri-clamp-cross-diaphragm-gamma/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

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

## Notes

- A fast gamma in 2 in tri-clamp: a hot cap and short spool over a torch, a cross as the sealed crankcase with the crank inside it, a diaphragm on top and a thin crankshaft out through a long bore to the flywheel.
- Numbers: Diaphragm 2 in at 12 mm: 11.3 mL swept · displacer Ø46 × 60 at 12 mm: 19.9 mL swept · dead volume 68.1 mL · swept / dead 0.166

## Sizes

| subsystem | object | parts | qty | note |
|---|---|---|---|---|
| None | tri-clamp-cross-engine-frame | cross-engine-frame-2in | 1 | base, wall, gussets |
| None | tri-clamp-torch-stand | torch-stand-40 | 1 | on the base under the hot cap, post toward the front |
| None | socket-head-cap-screws-metric | shcs-m4x10 | 2 | torch stand to the base |
| None | set-screws-metric | set-m4x10 | 3 | centre the torch head in the stand ring |
| None | tri-clamp-end-cap | tc-cap-2in-flat | 2 | hot cap (face up, over the flame) and the +X branch |
| None | tri-clamp-hot-gasket | hot-gasket-2in | 1 | hot joint |
| None | tri-clamp-heat-shield | heat-shield-2in | 1 | on the hot clamp |
| None | tri-clamp-spool | tc-spool-2in-3in | 1 | hot cylinder with the cap: displacer inside |
| None | tri-clamp-jacket-shell | jacket-half-2in-56 | 2 | band round the hot spool; the fill is the builder's choice |
| None | tri-clamp-jacket-shell | jacket-port-cap | 2 | one per jacket half |
| None | socket-head-cap-screws-metric | shcs-m4x30 | 4 | jacket ears |
| None | hex-nuts-metric | nut-m4 | 6 | jacket ears (4), hanger ears (2) |
| None | sanitary-clamp-crosses | cross-2in | 1 | the crankcase: run vertical, branches along the crankshaft |
| None | tri-clamp-gasket | tc-gasket-2in | 3 | spool–cross, end cap, bearing cap |
| None | tri-clamp-clamps | clamp-half-2in | 10 | five joints, two halves each |
| None | socket-head-cap-screws-metric | shcs-m5x30 | 10 | clamp bolts |
| None | hex-nuts-metric | nut-m5 | 12 | clamp nuts (10), hanger bar (2) |
| None | tri-clamp-cross-crankcase-insert | crankcase-insert-2in | 1 | fills the run; Ø3 displacer-rod guide; crank chamber |
| None | tri-clamp-cross-branch-plug | branch-plug-2in-blind | 1 | end-cap branch |
| None | tri-clamp-cross-branch-plug | branch-plug-2in-bore16 | 1 | bearing-cap branch |
| None | tri-clamp-bearing-cap | bearing-cap-2in-b3 | 1 | −X branch: two 623 seats, Ø3 bore 75.1 long |
| None | tri-clamp-displacer | displacer-shell-2in-60 | 1 | Ø46 × 60, 0.75 radial gap, 12 stroke |
| None | tri-clamp-displacer | displacer-cap-2in | 1 | closes the shell, holds the rod |
| None | stirling-crankshafts | crankshaft-3x60 | 1 | displacer rod (Ø3 × 60), through the insert's guide |
| None | stirling-crankshafts | crankshaft-3x44 | 1 | diaphragm rod (Ø3 × 44) |
| None | rod-clevises | rod-clevis-3mm | 2 | displacer rod, diaphragm rod |
| None | connecting-rods-623 | conrod-30 | 2 | diaphragm (in its clevis gap) and displacer (beside its clevis) |
| None | ball-bearings-metric | bearing-623 | 6 | con-rod eyes (4), bearing cap (2) |
| None | tri-clamp-cross-crank-webs | inner-crank-web-hub-r6 | 1 | on the shaft end |
| None | tri-clamp-cross-crank-webs | inner-crank-web-link-r6 | 1 | on the diaphragm pin; carries the displacer pin |
| None | dowel-pins-metric | dowel-3x12 | 3 | diaphragm crank pin, displacer crank pin, diaphragm clevis pin |
| None | dowel-pins-metric | dowel-3x20 | 1 | displacer clevis pin, con-rod beside the clevis |
| None | shaft-spacers | spacer-3mm-t2 | 1 | on the displacer clevis pin between clevis and con-rod |
| None | shaft-spacers | spacer-3mm-t1 | 2 | hub web to inner 623; outer 623 to flywheel |
| None | metric-shafts | shaft-3x100 | 1 | crankshaft |
| None | nut-pocket-flywheels | flywheel-100-m8-b3 | 1 | outside the bearing cap, hub toward the cap |
| None | hex-nut-weights | nut-m8 | 12 | one in each rim pocket |
| None | tri-clamp-diaphragm-head | diaphragm-head-2in | 1 | on the top of the run: the power diaphragm, rod inward |
| None | tri-clamp-diaphragm-membrane | membrane-2in | 1 | clamped in place of the gasket |
| None | tri-clamp-diaphragm-disc | diaphragm-disc-2in | 1 | gas side of the membrane, boss inward, carries the rod |
| None | tri-clamp-diaphragm-disc | diaphragm-backing-2in | 1 | head side of the membrane |
| None | socket-head-cap-screws-metric | shcs-m2x8 | 3 | heads on the head side, through backing disc, membrane and centre disc |
| None | hex-nuts-metric | nut-m2 | 3 | on the centre disc |
| None | set-screws-metric | set-m3x4 | 5 | grubs: displacer cap, diaphragm disc, two clevises, flywheel |
| None | set-screws-metric | set-m3x3 | 1 | hub web on the shaft |
| None | spool-hanger-collars | hanger-2in-tab | 1 | on the cross's lower run, bar to the wall |
| None | spool-hanger-collars | hanger-2in-plain | 1 | closes the hanger |
| None | socket-head-cap-screws-metric | shcs-m4x20 | 2 | hanger ears |
| None | socket-head-cap-screws-metric | shcs-m5x25 | 2 | hanger bar through the wall |

## Where the files are

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

## Build order

1. Frame on the bench; torch stand on the base with two M4 × 10; torch head in the ring, three M4 set screws.
2. Hot cap face up; hot gasket, 3 in spool, clamp; heat shield on the clamp; jacket halves round the spool with four M4 × 30, port caps in.
3. Displacer shell and cap with the Ø3 × 60 rod in the cap's grub; displacer into the spool; rod clevis on the rod top.
4. Type B gasket, cross (branches along the shaft line), clamp; spool hanger on the lower run, bar to the wall with two M5 × 25.
5. Insert down the run over the rod onto the gasket lip; blind branch plug, gasket, end cap, clamp on +X; bored plug, gasket, bearing cap with its two 623s, clamp on −X.
6. Shaft in from the flywheel side through the cap; spacer, hub web with its grub; con-rods with their 623s; diaphragm pin through hub web and diaphragm con-rod; link web on the pin with the displacer pin and con-rod; displacer con-rod to its clevis beside the spacer on the Ø3 × 20 pin.
7. Diaphragm: backing disc, membrane, centre disc with three M2 × 8 and nuts; Ø3 × 44 rod in the boss; rod clevis on the con-rod with the Ø3 × 12 pin; membrane on the top face, head over it, clamp.
8. Spacer and flywheel with its twelve nuts on the shaft outside the cap.

All printed STLs: https://xemstudio.com/objects/list-tri-clamp-cross-diaphragm-gamma/stl-list.txt

## Questions

**What parts do I need for the tri-clamp cross diaphragm gamma?**

49 parts, every one a free STEP/STL on this site; see the table and the build order on this page.

**Why is the diaphragm on top and not on a side branch?**

The cross's two branches share one axis. With the shaft along it, both rods have to run across it, so they come in from the top and bottom of the run.

**Which way does it turn, and where does the 90° come from?**

The displacer pin sits a quarter turn on from the diaphragm pin on the link web. Turning clockwise seen from the flywheel side, the displacer leads the diaphragm by 90° (the first harmonics of the two strokes are 90.0° apart with the 30 mm con-rods).

**Where can the gas leak out?**

Only along the crankshaft, through the 75.1 mm long Ø3 bore in the bearing cap; every other joint is a clamped gasket or the clamped membrane.

## Fits with

- [Tri-clamp bearing cap: 2 in cap with a long Ø3 shaft bore and two 623 seats](https://xemstudio.com/objects/tri-clamp-bearing-cap/)
- [Inner crank webs for the tri-clamp cross gamma: two throws 90° apart on a Ø3 shaft](https://xemstudio.com/objects/tri-clamp-cross-crank-webs/)
- [Crankcase insert for a 2 in tri-clamp cross: displacer-rod guide, crank chamber and run filler](https://xemstudio.com/objects/tri-clamp-cross-crankcase-insert/)
- [Branch plugs for a 2 in tri-clamp cross crankcase](https://xemstudio.com/objects/tri-clamp-cross-branch-plug/)
- [Frame for the 2 in tri-clamp cross diaphragm gamma](https://xemstudio.com/objects/tri-clamp-cross-engine-frame/)
- [Sanitary clamp crosses (9MP): ½ to 4 in](https://xemstudio.com/objects/sanitary-clamp-crosses/)
- [Tri-clamp diaphragm head: 1.5 and 2 in, membrane in place of the gasket](https://xemstudio.com/objects/tri-clamp-diaphragm-head/)
- [Tri-clamp jacket shell: clamp-on sealed jacket for a 2 in tube](https://xemstudio.com/objects/tri-clamp-jacket-shell/)
- [Torch stand for a horizontal tri-clamp hot leg](https://xemstudio.com/objects/tri-clamp-torch-stand/)
- [Build list: Tri-clamp tee diaphragm gamma, 2 in](https://xemstudio.com/objects/list-tri-clamp-tee-diaphragm-gamma/)