Do you want to know the secret to sharpening?
Here it is....
ready?
There are 2 secrets to sharpening.
SHAPE and FINISH
The shape of the edge (geometry question) and the finish of the edge (rougher or finer grit used at the last stage) determines how your knife will cut.
NEVER MIND any talk about x strokes this side, then flip and do this and that and you can split hairs. You need to understand what is going on when sharpening, so that you can use any gear you need and any technique you think will help to get the job done.
Sharpening is also about practice. I'd recommend the following to help you learn about sharpening.
Not knowing what gear you have, if you really want to learn how to sharpen a knife I'd recommend you get a coarse stone, or a coarse/fine combo stone from a store. Don't spend too much money! I have seen Norton brand stones in Walmart in the US for around $10. Something like that is perfect. Now, get yourself a ceramic stick set-up like the Sharpmaker from Spyderco. You do not have to get a Sharpmaker!! I think it is a great piece of gear, but it is a lot of money to spend if you are learning. Around here I can get a simple set-up that includes a wooden base and 2 ceramic rods that fit into the base in a V shape. That simple set-up is under $20 Canadian. You also need a knife. If you don't have a knife to practice on, I'd recommend a Frosts Mora knife (check camping stores). Get the carbon steel model, it should be around $8.
OK, now you have your knife and you have to ask yourself what you want to do with it. Do you want to slice rope all day, or make it a general camp tool? We'll say you want to make your Frosts Mora into a camp tool, to do a lot of wood work while camping. So then as far as shape goes, you want a thin V or convex profile, and for the finish you want a finer finish to help with push cutting wood.
Generally speaking, if you want to slice with your knife, you need a coarser finish. If you want to push cut with your knife, you need a finer finish. Generally, for harder materials you need a thicker edge, for finer materials you want a thinner edge. Shape and finish is what its about!
OK, back to the Mora. Now, it probably come sharp, but ignore that. In fact, I would recommend slicing with the edge into the edge of the coarse stone to get rid of the edge!!!
What you'll end up doing in this sharpenign tutorial then is setting up a micro-bevel. A microbevel is a small, very very small bevel on the bery edge of the knife. If you want to shape the edge to, say, 40 degrees, you don't need to sharpen the whole thing to 40 degrees. You will get better performance, and have an easier time sharpening, if you thin the whole edge bevel to, say 30 degrees and then set a micro-bevel at 40 degrees. The thinner main edge helps the knife penetrate what you are cutting (shape) and the micro-bevel will do the actual cutting. The microbevel is easy to set, fast to set, easy to make it nice and even, and fast to touch-up.)
DB was right when he said to keep the sharpening even. So do whatever you need to sharpen the knife, just keep things even. Lets assume then that you have, for arguments sake, a Spyderco Sharpmaker (again, NOT necessary, but I do recommend it.) The sharpmaker lets you set the stones in at 40 degrees and 30 degrees. For your Frosts Mora camp knife, lets use the 40 degree setting for the micro-bevel. That means you need to sharpen the main edge bevel at less than 40 degrees. Lets go with 30 degrees. What is 30 degrees? Eh, hard to say. One way to check is to mark your knife edge with a magic marker, and then take some strokes on the sharpmaker with the 40 degree setting (or whatever microbevel system you get.) Where the marker is removed is an indication of what a 40 degree angle setting is. Now when you lay your knife on the coarse stone you got and take a a few strokes, look at the very edge again, you should have removed material ABOVE that 40 degree angle indication line you made with the sharpmaker. You'll learn pretty quickly what is thinner or thicker than whatever microbevel you want to set.
So go ahead and start thinning your main edge bevel. Take slices, do circles, whatever. Just alternate sides regularly to keep things even. I do exactly the same thing with my belt sander when I am making a knife and formign the primary grinds or setting the edges! Its all about shape and finish.
I like to do small circles just because it goes faster for me. Once you get close to getting right to the edge, things will change a bit. How do you know you are at this stage? Well, you will with experience! But two ways to know are either you can constantly check for burr formation, or look at your magic marker line. As you thin otu the bevel, that magic marker will be disappearing closer and closer to te very edge. Once the marker is gone from the very edge (an dis now gone from the whole edge), you are proably done on that side. I recommend using both checks, and eventually you won't need the magic marker. So once youa re close to the edge on one side, just do strokes on that side until you form a burr. The burr is where tou have sharpened right to the very edge and now the very thin edge had flipped over to the opposite side of the knife you were sharpening on. To check for the burr gently drad your fingers perpendicular to the edge, from the spine of the knife past the edge (spine down), and feel the burr catch or drag on your finger. I hope this part is very clear. you are not slicing your finger alogn the edge! You are dragging your fingers very lightly not lengthwise along the knife, but widthwise. And you just want to feel the burr drag on your finger.
Once you have a good burr (not a slight one) along all of the edge, you will flipthe knife over and do strokes or circles until you have a burr on the opposite side of the knife again. If there are parts of the knife that don't have a burr yet, concentrate on those parts before flipping the knife over. You need a nice burr alogn the whole edge. When you flip the knife over to set a burr on the other side, it will go quick! Repeat doing what you did before, setting a nice even burr ont he whole edge.
Now you have thinned the edge! If you have a coarse/fine stone, you can then use the fine side on your newly formed edge bevel. Since the edge bevel has now been thinned out, you won't be doign any more thinning (shaping). You will be changing the finish. Think about this again. Once you have set your main edge bevel at 30 degrees, the hard work is over! So any more work at the 30 degree setting will be changing the finish. Also, since you have already removed the steel at the edge to make a 30 degree setting, when working on the fine stone you'll find things go quick again.
Why go with the fine finish on the primary edge bevel? It will help with 2 things. A lot of how an edge works is what the steel is like behind the very edge. If you polish this part, it will make cutting smoother, as you have a nice smooth surface penetrating what you are cutting. Also, it helps prepare things for your micro-bevel setting tool. This is especially important if you don't use a sharpmaker. The sharpmaker has coarser and finer stones, so you could probably, without much trouble, go from the coarse bench stone t the coarse ceramics and then the fine ceramics of the Sharpmaker without difficulty. But going from a coarse bench stone finish to setting a microbevel with a fine ceramic is a bit of a jump. You can still do it, but it will just take more time.
After your coarse (or fine) stone work, having set the primary edge bevel to 30 degrees, I like to do a few alternating strokes, still at the 30 degree angle, just to align the burr. This just makes setting the micro-bevel easier I find.
OK, set up your micro-bevel system. Usually all you do is hold your knife between the V sticks and take slices. Do alternating slices and do 20 or so per side.
VOILA!
You don't need much work on the micro-bevel setting device because you have thinned the primary edge out so nicely already. The microbevel will go on so easy and fast you will be surprised.
Go ahead and slice some paper and check your edge out! If it drags at spots, do some more work on your micro-bevel setting device. If you have a strop, go ahead and strop the knife edge as well and enjoy that finish!
I hope this helps. I bet you know a lot of this information already, and you probably have your own sharpening gear. Just remember it is the information and principles that matter; adapt them to you and your gear.
As I said, I have a belt sander that I use to make knives with and sharpen knives on. I do exactly as I typed herw with that gear. I set my mai edge bevels with my belts and set micro-edge bevels with my sharpmaker.
Sometimes I do different things, sich as setting convex bevels and stropping off the burr. But here the principles are the same: I set the shape I want and then the finish.
If you can thin an edge out and put on a microbevel, the rest of sharpening will come easy.
Good luck, I hope this helps!
I'm sincerely interested in why you don't think a constant grinding angle is essential. Without a constant grinding angle you just keep regrinding a new edge, instead of sharpening the edge that you made on your last pass. In essence you're starting from scratch with each pass you make.
