Learning to sharpen a knife by feel makes sure your knives last longer and are easier (and safer) to use -- even more so than an automatic sharpener, which can grind your knives down and shorten their life. This method, from sharpening master Peter Nowlan, is a solid "four pressure" system you can learn at home.
The video above is a good tutorial from start to finish on how the method works, but if you don't have time for the full thing (or you're cribbing for later), here's how it shakes out, from the accompanying article over at KnifePlanet (linked below):
The levels of pressure are from P4-P1 and this is just a designation I chose, I prefer NOT to equate the numbers to actual degrees of pressure, i.e. P4 does not necessarily mean 2kg of pressure.
The reason I say this is so that nobody feels locked in to using 2kg of pressure initially, to form the burr, you need to use the amount of pressure necessary to create a burr on the knife you are sharpening. It may be very very dull and therefore require more pressure than a knife that is not so bad, so you wouldn't need to use that much pressure. HOWEVER, in the process of going from P4 down to P1, P4 is still the most pressure you will use, whether it is 4 or 1kg.
P4 -- therefore is the most amount of pressure used to form a burr on both sides of the knife and P4 pressure is only used once in the entire process with one knife. As soon as the burr is formed you need to reduce your starting pressure by 50%. LESS is MORE, go easy to start and adjust as necessary. In other words, when you approach the knife with the intent of forming the burr, use moderate pressure to start and see how it goes, if you think you need to notch it up a bit, do so but just be vigilant. (More on that at the end)
P3 -- is a significant reduction in pressure, still on the same stone but remember, you do not want to form another burr so just be mindful of that, especially on those coarse stones. Your goal is coarse stone refinement, just cleaning the edge and you don't need to spend much time at these level of pressure. I just go from heel to tip and then back from tip to heel and then flip the knife and repeat. Then I lower the pressure again to P2.
P2 -- Pressure is very light pressure, this amount of pressure would not form a burr on a coarse stone, well it would take an eternity, it is that light, it is very a very soft and focused movement as you CARESS the stone with the edge of the knife, all at the same angle of course, as close to it as you can manage that is.
P1 -- This is the least amount of pressure you can manage to maintain without dropping the knife. This is really a nice and very easy motion as you move that edge over the stone from heel to tip, tip to heel then repeat on the other side. (Or if you start at the tip, from tip to heel and back from heel to tip)
The whole guide is worth a read if you want to follow along step-by-step as well, but the important things to remember here are to grab yourself a good whetstone and take things slow and easy. It will take practise before you can move more quickly, but as you get the feel down you'll learn what the "burr" feels like, and what it feels like when you smooth it out. Hit play on the video above, or the link below for more.