Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Hi Trevor,  you might continue to experience occasional flywheel loosening even with well to9oòrqued typical hardened set screws as the flywheel-crankshaft interface receives hard impulse hits. Hardened, serrated tipped self-locking type set screws grip the shaft better. Unless you drill & tap a new set screw hole about 90° to 100° separation, you're stuck with the Worst case, inferrior, 180° set screw locations. You might consider using Loctite Red on the set screws & glueing the flywheels to crank shaft with "on demand" debondable adhesive since after sorting out the crankshaft bearing issues flywheels seldom need removal. Have fun improving the beast, ...tom.