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Bolt-on counterweight arcs R15, R20 and R25
What does a bolt-on counterweight for a flywheel look like? · Hardware · basis: 120° ring segment 6 thick, 8 mm radial width, three Ø3.2 holes at R − 4
Long Earth Society build part. Balanced cranks for the 2 in gamma. 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 120° arc 6 thick and 8 mm wide radially: R15/R7, R20/R12, R25/R17 (outer / inner).
- Three Ø3.2 holes (M3 clearance) at R − 4 (R11, R16, R21), at the centre and ±40°.
- It bolts to a flywheel or crank disc opposite the pin; moving it along matching holes trims the balance.
Sizes
| file | outer R | inner R | arc | thickness | holes |
|---|---|---|---|---|---|
| bolt-on-counterweight-r15 | 15 | 7 | 120° | 6 | 3 × Ø3.2 at R11 |
| bolt-on-counterweight-r20 | 20 | 12 | 120° | 6 | 3 × Ø3.2 at R16 |
| bolt-on-counterweight-r25 | 25 | 17 | 120° | 6 | 3 × Ø3.2 at R21 |
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 |
|---|---|---|---|---|
| bolt holes | Ø3.2 | M3 screw clearance (ISO 273 fine) | designed | bolt-on-counterweight-* |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| Wikipedia | Engine balance | web | CC BY-SA 4.0 (text) |
| Wikipedia | Crankshaft | web | CC BY-SA 4.0 (text) |
| Long Earth Society | Engine builds | web, video | LES site |
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
| bolt-on-counterweight-r15 | bolt-on counterweight arc, outer R15 / inner R7, 120°, 6 thick, 3 × M3 clearance (Ø3.2) at R11; add to any flywheel or disc opposite the pin | STEP · STL |
| bolt-on-counterweight-r20 | bolt-on counterweight arc, outer R20 / inner R12, 120°, 6 thick, 3 × M3 clearance (Ø3.2) at R16; add to any flywheel or disc opposite the pin | STEP · STL |
| bolt-on-counterweight-r25 | bolt-on counterweight arc, outer R25 / inner R17, 120°, 6 thick, 3 × M3 clearance (Ø3.2) at R21; add to any flywheel or disc opposite the pin | STEP · STL |
Plain text: sheet.txt · JSON: /api/geometry?object=bolt-on-counterweights
How it fits
Goes in or on
Spoked flywheels Ø50 to Ø150 × 10bolted to the face opposite the pinAlternatives
Flywheels Ø100–Ø200 with hex-nut rim pocketsnuts in one half of the rimAlso needed
Socket head cap screws, M2–M83 × M3You might also need
Questions
Where does a bolt-on counterweight go?
On the flywheel or crank disc, centred opposite the crank pin, on three M3 screws.
What is the hole spacing?
Three Ø3.2 holes at R − 4, 40° apart.