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Tri-clamp crank web: Ø8 bore, Ø3 crank pin at 8, 12 and 18 mm throw
What crank web gives a 24 mm stroke on an 8 mm shaft? · Hardware · basis: Stroke 16 / 24 / 36 mm (0.46 × bore) for the 1.5 / 2 / 3 in pistons; web Ø = 2 × (throw + 6)
Long Earth Society build part. Full-bore pistons for the tri-clamp beta and alpha engines. The engines
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. Mating features
- sizes
- 3 in table
Notes
- A round crank web: Ø8 shaft bore, Ø3 crank-pin hole at half the stroke, and an Ø2.5 radial hole for an M3 grub onto the shaft. Two webs face each other with the pin between them.
- 1.5 in: Ø28, pin at 8 mm (16 mm stroke). 2 in: Ø36, pin at 12 mm (24 mm stroke). 3 in: Ø48, pin at 18 mm (36 mm stroke). All 5 mm thick.
- Shaft order: tower, web, con-rod, web, tower with 1 mm gaps, inside the crank frame's 21 mm tower gap; the crank pin between the webs is Ø3 × 19.
Sizes
| spool_in | web_od_mm | shaft_bore_mm | pin_hole_mm | throw_mm | stroke_mm | thickness_mm |
|---|---|---|---|---|---|---|
| 1.5 | 28 | 8 | 3 | 8 | 16 | 5 |
| 2 | 36 | 8 | 3 | 12 | 24 | 5 |
| 3 | 48 | 8 | 3 | 18 | 36 | 5 |
Mating features
Drawn at the exact size. Open press, slide, run and socket features by your process's clearance; leave designed gaps and clamp fits as drawn.
| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| crank-web shaft bore | Ø8 | Ø8 D-flat crankshaft | slide | crank-web-* |
| crank-web pin hole | Ø3 | Ø3 crank pin | press | crank-web-* |
| crank-web grub hole | Ø2.5 | M3 tap drill | designed | crank-web-* |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| Long Earth Society | Tri-clamp Stirling engine builds | web, video | LES site |
| James R. Senft | An Introduction to Stirling Engines (piston fit and leakage) | book | Moriya Press verify |
| ASME | BPE tube dimensions (16 ga sanitary tube) | standard | ASME verify |
Free files
★ Free files 3 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json
| crank-web-1.5in-s16 | 1.5 in crank web: Ø8 bore on the D-flat shaft with an M3 tapped grub hole, Ø3 pin at 8 mm (16 mm stroke); two per crank | STEP · STL |
| crank-web-2in-s24 | 2 in crank web: Ø8 bore on the D-flat shaft with an M3 tapped grub hole, Ø3 pin at 12 mm (24 mm stroke); two per crank | STEP · STL |
| crank-web-3in-s36 | 3 in crank web: Ø8 bore on the D-flat shaft with an M3 tapped grub hole, Ø3 pin at 18 mm (36 mm stroke); two per crank | STEP · STL |
Plain text: sheet.txt · JSON: /api/geometry?object=tri-clamp-crank-web
How it fits
Goes in or on
Tri-clamp crank frametwo webs between the towers on the Ø8 shaftConnects to
Tri-clamp con-rodØ3 crank pin through the rod's 623Alternatives
Counterweighted crank discs, Ø5 bore, 10 to 30 mm…balanced websAlso needed
Crankshafts Ø3, Ø5 and Ø8 with full-length D-flatØ8 shaft, Ø3 × 19 crank pin
Set screws, M3–M8M3 grubQuestions
What stroke do the tri-clamp crank webs give?
16 mm (1.5 in), 24 mm (2 in) and 36 mm (3 in): the Ø3 pin is 8, 12 or 18 mm off the Ø8 bore.
How is the web fixed to the shaft?
An M3 grub in the Ø2.5 radial hole, onto the Ø8 shaft (on its flat if it has one).