Knife edge crank

[homieGdog]

To the old school builders and modifier, has any of you knife edge a Briggs and Stratton crankshaft. I'm in the process of building a 5HP motor and I was wandering has any of you knife edge a crankshaft before?

 

[isaiah3g]

I know it's been nearly 5 months, but any word from anyone else on this?

 

[Mariah]

Are you referring to a sharp right angle at the edge of the bearing surface? If so, that is a bad practice because it creates a stress point that is prone to failure. A radius is put there to relieve stress and fatigue that will cause a crankshaft to fail. If you go to a diesel engine repair shop they usually have a broken crankshaft for a conversation piece...they always seem to crack right at the edge of a journal.

 

[mckutzy]

Im going to guess at he's referring to balancing a shaft... Usually done with 2 parallels thin to a knife edge....
Did some similar work with electric motor rotors and armatures...

 

[EVOL Tweety Bird]

Yeah you knife edge the crank's weights. Hot rodding trick. The crank then knives through the oil, instead of the original flat edge slamming into the oil. Decreases friction, and also removes weight from the crank. Crank would have to be rebalanced afterwards.