I'm a new contributor to SMC forums and this is my first posting, so please excuse any goofs here...
I've been retired for three years now and I enjoy restoring old rusty/crusty bench planes as a hobby - for me it's rewarding to bring back to life an old tool. I've kept a couple, given away a few as gifts, and have even sold a few. I'm not a frequent woodworker, but am gratified when I get feedback that a plane I've restored is being used successfully by someone who is.
I watched many on-line videos on restoring and tuning-up planes and I'm always learning something new about that process.
For example, I was surprised when I first learned that the chip breaker was much more than just a gizmo to stiffen the iron.
Since then I pay much attention to the leading edge of the chip breaker when tuning-up and testing a plane that I'm trying to restore.
But what I haven't seen is a good explanation of best practices of when to adjust the frog forward or back. I understand that you'd want to have a mouth opening large enough to permit shavings to sail upwards without hitting parts of the mouth, but is there more to it than that? For example, if I just set the frog back leaving a larger opening in front of the cutting edge is that somehow suboptimal in how the iron cuts through the wood in certain situations? I *think* I've seen advice that you should move the frog forward if you're trying to get fine wispy shavings. Is that true, and if so why?