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

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

- Category: Stirling engines › Assembled engines
- 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-rd-gamma/ · JSON: https://xemstudio.com/api/geometry?object=list-tri-clamp-rd-gamma · Plain text: https://xemstudio.com/objects/list-tri-clamp-rd-gamma/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.** True size, with no printing tolerance added.

## Notes

- The Ringbom's cup, tee and power head with the displacer on the crank: a pushrod from a second crank pin to a bell crank on the gland cap.
- Numbers: Numbers (with the optional finned cooler; cold end taken at 320 K): power swept 20.0 mL, displacer swept 30.4 mL, dead volume 57 mL (swept/dead 0.35); Schmidt work at 650 / 320 K and 1 bar mean 0.33 J per turn (1.39 pressure ratio, ±16 kPa); shaft power about 0.4–1.7 W at 300–600 rpm (0.25–0.5 of Schmidt).

## Sizes

| subsystem | object | parts | qty | note |
|---|---|---|---|---|
| None | tri-clamp-rd-engine-frame | rd-frame-2in | 1 | base, wall, gussets |
| None | tri-clamp-torch-stand | torch-stand-40 | 1 | on the base, post toward +Y; the heat source is a torch flame 40 mm under the cup |
| 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-cups | cup-2in-150 | 1 | the hot end and displacer cylinder in one piece: no joint near the flame |
| None | spool-hanger-collars | hanger-2in-tab | 1 | on the cup under the top clamp; bar to the wall |
| None | spool-hanger-collars | hanger-2in-plain | 1 | closes the hanger |
| None | socket-head-cap-screws-metric | shcs-m5x25 | 2 | hanger bar through the wall |
| None | socket-head-cap-screws-metric | shcs-m4x20 | 2 | hanger ears |
| None | hex-nuts-metric | nut-m4 | 2 | hanger ears |
| None | tri-clamp-finned-cooler | cooler-half-2in-56 | 2 | optional: clamp-on fin halves on the cup under the hanger (the cold end of the displacer cylinder); without them the engine runs with less power, or cool that part of the cup any way you like |
| None | socket-head-cap-screws-metric | shcs-m4x30 | 4 | optional: cooler ears (only with the cooler) |
| None | hex-nuts-metric | nut-m4 | 4 | optional: cooler ears (only with the cooler) |
| None | rolling-diaphragm-top-hat | rd-diaphragm-1.50-h1.50 | 1 | 1.50 in bore, 1.50 in high, flat flange: clamped in the joint in place of a gasket |
| None | tri-clamp-rd-power-head | rd-power-head-2in | 1 | standard 2 in clamp face, Ø38.10 cylinder, bushing seat, crank tower |
| None | tri-clamp-rd-power-head | rd-seat-ring-2in | 1 | in the head's face recess, behind the diaphragm flange |
| None | tri-clamp-clamps | clamp-half-2in | 6 | 3 joints, two halves each |
| None | socket-head-cap-screws-metric | shcs-m5x30 | 6 | clamp bolts |
| None | hex-nuts-metric | nut-m5 | 8 | clamp nuts (6), hanger bar (2) |
| None | sleeve-bushings | bushing-5x8x12 | 2 | back to back in the head's Ø8 seat: guide the tube rod |
| None | tri-clamp-rd-piston | rd-piston-2in | 1 | Ø33.27, never touches the bore |
| None | tri-clamp-rd-piston | rd-retainer-26-blind | 1 | clamps the diaphragm head on the crown |
| None | button-head-screws-metric | button-m3x8 | 3 | retainer screws into the crown |
| None | tube-piston-rods-5mm | tube-rod-5x3.4x80 | 1 | piston to yoke, through the bushings |
| None | tri-clamp-rd-yokes | rd-yoke-tube5 | 1 | on the tube rod's end |
| None | set-screws-metric | set-m3x3 | 1 | tube yoke grub |
| None | connecting-rods-623 | conrod-80 | 1 | power |
| None | counterweighted-crank-discs | cw-crank-disc-stroke20 | 1 | 20 mm stroke, overhung on the shaft end |
| None | stirling-crankshafts | crankshaft-5x80-dflat | 1 | disc face to flywheel hub |
| None | shaft-spacers | spacer-5mm-t5 | 1 | disc hub to the front bearing |
| None | shaft-spacers | spacer-5mm-t1 | 1 |  |
| None | ball-bearings-metric | bearing-625 | 2 | in the tower |
| None | shaft-collars | collar-5mm | 1 | behind the tower |
| None | nut-pocket-flywheels | flywheel-150-m10-b5 | 1 | on the shaft's far end |
| None | hex-nut-weights | nut-m10 | 18 | one in each rim pocket |
| None | sanitary-clamp-tees | tee-2in | 1 | standard 2 in equal tee: run upright on the cup, branch toward +X for the power head |
| None | tri-clamp-gasket | tc-gasket-2in | 2 | Type B: cup to tee, tee to gland cap |
| None | tri-clamp-rd-tee-inserts | rd-tee-insert-2in-gamma | 1 | fills the tee's run between the two gasket lips |
| None | tri-clamp-rd-tee-inserts | rd-branch-insert-2in | 1 | fills the tee's branch; its spigot locates the run insert |
| None | tri-clamp-rd-gland-caps | rd-gland-cap-2in-gamma | 1 | closes the top of the tee's run, carries the rod's gland |
| None | set-screws-metric | set-m5x6 | 1 | plug in the gland cap's M5 port (or a gauge or one-way valve) |
| None | sleeve-bushings | bushing-3x5x6 | 2 | the displacer rod's gland, one at each end of the gland cap's boss |
| None | tri-clamp-displacer | displacer-shell-2in-120 | 1 | Ø46 × 120, 0.75 radial gap, 18.3 stroke |
| None | tri-clamp-displacer | displacer-cap-2in | 1 | closes the shell, holds the rod |
| None | displacer-rods | rod-3x350 | 1 | displacer rod: up through the tee insert and the gland |
| None | displacer-rods | rod-3x300 | 1 | pushrod: crank pin 2 to the bell crank |
| None | rod-clevises | rod-clevis-3mm | 3 | displacer rod top, both pushrod ends |
| None | tri-clamp-rd-link-webs | rd-link-web-r7-45 | 1 | on crank pin 1, carries pin 2 |
| None | bell-cranks | bell-crank-30x30-90 | 1 | on the gland cap's post: arm A up to the pushrod, arm B over the displacer rod |
| None | connecting-rods-623 | conrod-40 | 1 | bell crank arm B to the displacer rod's clevis |
| None | ball-bearings-metric | bearing-623 | 5 | con-rod eyes (4), bell-crank pivot (1) |
| None | dowel-pins-metric | dowel-3x12 | 2 | tube-yoke stub pin, bell-crank arm B |
| None | dowel-pins-metric | dowel-3x16 | 1 | bell-crank pivot in the post |
| None | dowel-pins-metric | dowel-3x20 | 4 | crank pin 1; crank pin 2 through the pushrod clevis; arm A through the pushrod clevis; displacer clevis pin with the con-rod beside it |
| None | set-screws-metric | set-m3x4 | 8 | grubs: displacer cap, 3 clevises, piston, crank disc, collar, flywheel |

## Where the files are

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

## Build order

1. Frame, torch stand, cup with its hanger (and the optional cooler) as on the Ringbom.
2. Displacer: shell, cap, Ø3 × 350 rod (grub); into the cup. Type B gasket, tee, clamp; run insert and branch insert as on the Ringbom. Type B gasket, gamma gland cap (two 3 × 5 × 6 bushings pressed in), clamp. Rod clevis on the rod top.
3. Power head as on the Ringbom, with the link web and pin 2 on the crank.
4. Bell crank on the post (623 on the Ø3 × 16 pin); conrod-40 from arm B to the rod clevis (Ø3 × 20 through the clevis, con-rod beside it); pushrod clevises on arm A and on pin 2.

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

## Questions

**What parts do I need for the rolling-diaphragm gamma?**

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

**How is the displacer phased?**

Pin 2 is 45° from pin 1 on the link web; with the pushrod and bell crank the displacer leads the power piston's volume by close to a quarter turn.

**Do I need the finned cooler?**

No. It is an optional heat exchanger that clamps on the plain cup; without it the engine runs with less power. Any cooling of the top of the cup works, even a wet rag. The numbers above assume the cold end held near 320 K.

## Fits with

- [Tri-clamp gland caps, 2 in: end caps with a rod gland, an M5 port and a stop bridge or bell-crank post](https://xemstudio.com/objects/tri-clamp-rd-gland-caps/)
- [Tee inserts, 2 in: volume fillers for the run and branch of a standard 2 in equal tee](https://xemstudio.com/objects/tri-clamp-rd-tee-inserts/)
- [Sanitary clamp tees and short-outlet tees (7MP, 7MPS): ½ to 4 in](https://xemstudio.com/objects/sanitary-clamp-tees/)
- [Link webs: a second crank throw on the first crank pin](https://xemstudio.com/objects/tri-clamp-rd-link-webs/)
- [Bell cranks: 30 × 30 and 20 × 40 mm arms at 90°](https://xemstudio.com/objects/bell-cranks/)
- [Top-hat rolling diaphragm, 1.50 in bore, flat flange: the one that clamps in a 2 in tri-clamp joint](https://xemstudio.com/objects/rolling-diaphragm-top-hat/)
- [Tri-clamp rolling-diaphragm power head, 2 in: standard clamp face, cylinder, rod guide and crank tower, with its diaphragm seat ring](https://xemstudio.com/objects/tri-clamp-rd-power-head/)
- [Tri-clamp finned cooler: clamp-on halves for a 2 in tube](https://xemstudio.com/objects/tri-clamp-finned-cooler/)
- [Build list: Tri-clamp rolling-diaphragm Ringbom, 2 in](https://xemstudio.com/objects/list-tri-clamp-rd-ringbom/)
- [Build list: Tri-clamp tee diaphragm gamma, 2 in](https://xemstudio.com/objects/list-tri-clamp-tee-diaphragm-gamma/)