A lot of the books covering lathe tool sharpening are a bit lacking in details Chris. Too many of them seem to cover the powered grinder sharpening well enough, but neglect or may not even mention the needed honing after. Yes a ground tool right off the grinder will cut, but not nearly as well or with the same surface finish quality as one that’s been properly honed. Paraphrasing George Thomas, “a rough ground tool can not produce a fine finish” or words to that effect. And a well honed tool with a slight tip radius will also last much longer. Many times you don’t even need to regrind the tool, just re-hone it and it’s as good as new.
However the term honing is a bit subjective as far as how sharp the tools cutting edges should be. Pulling the tools honed edge with very light pressure down your thumbnail, it should be sharp enough to start to raise a chip is one way. A proper and very good quality stone with a recognizable brand name such as a Norton isn’t cheap. And cheap stones aren’t worth buying. And after enough use, they need to be re-flattened. Instead I chose to buy from a woodworking tool dealer a diamond coated plate. They stay flat, last almost forever, hone quicker and in some cases, are cheaper than a good stone. I also use that plate with a few drops of light weight oil. Something easy to get like 3 n 1 if it’s available in the UK, or sewing machine oil works fine.