Could you share the necessary theory with us, what a person needs to understand? Thanks
this is not the right thread but anyway.....
to sharpen you need to remove metal.
you don't need to remove metal in excess or too few.
the most important thing to have in mind is that there are different blades with different POU, each blade has a particular angle that works best for that purpose. for example, in a folder or a very small fixed blade, you don't need a thick edge with an obtuse angle, but a thin edge with acute angle, instead, if you have a big and heavy blade, most of the cuts will be made through pression and impacts and not through real cutting, in this case, you need a thick edge with obtuse angle, to absorb great abuses and even if it doesn't cut very well, that will work fine anyway.
in some extreme cases you don't need your tool sharp at all. for example, there is no big difference in an axe razor sharp or an axe that is pratically dull.
the axe works for pression and it will cut, split, chop because of it's weight and balance and general geometry and even if the edge is not razor sharp, it will work good anyway.
it's a very long thing to explain but you may have already understood the main points.
you need to remove metal on the edge in order to maximize the performances of the blade you're sharpening.
this is called WORKING ON EDGE GEOMETRY. this means that the edge of the knife once you've removed enough metal must have the correct geometry for his dedicated purpose.
now, once the edge has a correct geometry we can think about making it scary sharp, like a razor and more...
and to make it sharp you basically need to polish the edge.
to get the correct edge geometry you'll use coarse stones like 120-220-300 max grit stones. with this method you remove a LOT of metal quickly, but the edge will have "microserrations" that will ake it less sharp and will make the edge less durable.
to remove microserrations you simply jump to finer stones.
I sharpen my blades using only 2 japanese waterstones with combo grit.
the first stone is the 300-1000... I use the 300 to remove chips and restore the edge geometry I want ( I even reprofile edges free hand and sharpen standard V edges to convex edges on stone) than I start polishing the edge with the other side of the stone with the 1000 grit side.
once I've removed all the scratches of the 300 stone with the 1000 I'm ready to use the 4000 stone, and once I've removed the scatches of the 1000 I polish the edge with 8000 grit stone.
to give final polish to the edge and create a micro convex bevel on even a perfectly V edge, I simply strop the edge on leather with dry metal polish on it.
a great metal polisher is Metal Glo. once it's dry it removes a LOT of metal. it's a good options even to sharpen up to 1000 and then directly strop on metal glo.
you can use finer metal polishers to have a finer edge.
my method is easy because it's not important to do particular attention to the movements you do, and neither the directions of the blade while you're sharpening it. you just need to remove metal.
the only mistake may be drastically change the sharpening angle with your hand, but I think it's easy to begin with an inclination and then mantain about the same angle from beginning to the end... for example, if you sharpen in a range of 35-40° it's fine, but if you begin at 40°, than switch to 50, than to 25, the first mistake is that you have removed the very edge uring the strokes at 50°, and than, switching back at 25, you're not removing metal from te edge at all.
so, it's long to explain but, the easier thing to do to get a razor sharp knife is to start at an angle more acute than the one you need, for example at 25° and than your natural mistakes (because it's impossible for a human being to mantain the exact same angle durin all the sharpening) will let you have the desired edge angle of (for example) 35°. but if you start sharpening at the desired angle, you'll get an edge too obtuse, resulting in a blade that doesn't cut well.
further explainations will continue in private or if requested
