re: From Implement tine to Froe

Bigger logs I'll use wedges and a sledgehammer to split them - which gives you a pretty good idea of how hard you need to hit it :)
Froe's are generally better on smaller stull, the whole idea is that you can control the direction of the split, which is near impossible on larger logs - wedge the log with a brake and lever the handle to twist the iron in the direction you want to split.
If I can, I'll normally wait a month or so until a split naturally forms as the log dries, then use that as the start point so the froe or wedge doesn't need a sharp edge at all for that.