Tips for getting "shaving sharp"?

[NPT]

I'm pretty sure we're all assuming that we're starting with a properly designed knife, and not trying to sharpen a crowbar.,,

 

[Hengelo_77]

I'm pretty sure we're all assuming that we're starting with a properly designed knife, and not trying to sharpen a crowbar.,,

Yes but I say so to explain that shaving hairs is a neat little trick but not necessarily a sign of quality

 

[NPT]

I suspect I'm still not understanding something. Are you referring to having an edge that will shave hairs will not do you any good on a camp knife meant to hack up wood for your fire?

 

[Hengelo_77]

I mean that a knife can be shaving sharp but not cut well.
You can have a 1/16" edge shaving sharp, but it won't cut well

 

[A.McPherson]

My splitting axe starts the season shaving sharp, but I wouldn't try felling a tree with it.

That's what the felling axe is for.

The thinner the blade is, the less material has to be moved out of the way to continue the cut. That's what makes a knife cut well.

Of course the thinner the knife is, the weaker it is. That's why chopping knives (cleavers, competition cutters, some "fighting" knives) are thick, to make them tougher, less easy to break. Thus they don't cut as well as a thin kitchen knife.

The can all be just as sharp as one another, but toughness and ease of cut are always a compromise.