Xem Studiomeasured geometryLibrary › Stirling engines › Drives & mechanisms ·
Bell cranks: 30 × 30 and 20 × 40 mm arms at 90°
How do I make a bell crank with 3D printed parts? · Hardware · basis: Bell crank lever: output motion = input × (output arm / input arm); 90° between arms; Ø10 pivot pocket for a 623 bearing
Long Earth Society build part. Beta-engine linkage lever for the LES rigs. 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
- 2 in table
Notes
- Turns a push or pull through 90°. The 30 × 30 crank keeps the same travel; the 20 × 40 doubles it (or halves it, driven the other way).
- Pivot is a Ø10 pocket for a 623 bearing (OD 10); arm ends have Ø3 holes for pins and links.
- Used in the beta Stirling bell-crank drive to phase the displacer and piston.
Sizes
| arms | angle | ratio | pivot |
|---|---|---|---|
| 30 × 30 mm | 90° | 1:1 | Ø10 (623) |
| 20 × 40 mm | 90° | 1:2 | Ø10 (623) |
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 |
|---|---|---|---|---|
| pivot pocket | Ø10 | 623 bearing OD 10 | press | all |
| arm holes | Ø3 | Ø3 pins (turn in them) | run | all |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| Wikipedia | Bellcrank | web | CC BY-SA 4.0 (text) |
| Long Earth Society | Engine and rig builds on extrusion frames | web, video | LES site |
Free files
★ Free files 2 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json
| bell-crank-30x30-90 | bell crank, 30 × 30 mm arms at 90°, Ø10 pocket for a 623 bearing pivot, Ø3 arm holes | STEP · STL |
| bell-crank-20x40-90 | bell crank, 20 × 40 mm arms (2:1) at 90°, Ø10 pivot pocket, Ø3 arm holes | STEP · STL |
Plain text: sheet.txt · JSON: /api/geometry?object=bell-cranks
How it fits
Connects to
Four-bar linksØ3 arm holesAlso needed
Ball bearings, 683 to 6210 and flanged F6xx623 in the Ø10 pivot pocket
Dowel pins, 2–6 mmØ3 pivot and arm pinsYou might also need
Questions
What does a bell crank do?
It changes the direction of a push or pull, usually by 90°, and scales the travel by the ratio of its arms.