A simple 3-cylinder radial engine compatible with LEGO Technic.
Exploded view in 3d viewer: https://skfb.ly/6QL8R
Extra parts needed:
- Nitrile g...love
- Air balloon
Takes 4m of filament to print (about 5h at 20mm/s on my snail of a printer).
Will print a bit prettier with supports (80deg. overhang, touching buildplate) and ironing.
Parts with names starting with "X_" are optional.
You can insert one balloon into another to get thicker walls. Meant for 2-walled balloon. Idles well with one (with a flywheel), but will hardly pull any vehicle.
You can use metal M5 washer instead of printed one
Found that PLA isn't the best material for the design: isn't very slippery, and "fluid" (the clips stop pushing the parts together with time)
3d model print parameters
Printed well in PLA and PETG with 0.6 nozzle at 0.2 layer height....