For clarity, here's how I define terms used when discussing sharpening.
For the past few years I've been using regular V edges. Over time I've moved towards convex edges. I started out doing thin V grinds, then convexing the edge bevel into the primary grind. These days I do the whole bevel convex and I find myself preferring this method. Very easy to get hair whittling sharpness, sandpaper is cheap and readily available at many stores and it saves me time from having to convex the edge bevel as a seperate step like I used to. I'll still cover my old methods for those who prefer V edges.
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My sharpening equipment.
Reprofiling[/CENTER]
For this I have a DMT X course stone with a nice stand and cover. I superglued a DMT XX course steel plate to the cover. so I can use the base to the XC with it. These stones work really fast and are low maintenance. When reprofiling a knife I keep a damp towel handy to wipe off the removed metal periodically, keeping the stone fresh and grinding quickly.
I use heavy pressure and quick strokes. Edge leading or trailing makes no difference here since you won't be working with the edge, just go with what you're more comfortable with. I use edge trailing usually because I find it easier to control for this type of work.
The question of how thin to go often comes up when discussing reprofiling. How thin depends on if you plan to use a microbevel or not. For a large, flat ground knife like a Military, if I were going to use a microbevel I'd grind the secondary bevel at 5-8 degrees per side. If I were not, I'd use 10-12 degrees per side. For most of the steels Spyderco uses, I've found this to be slightly thicker than what I need for my typical uses (Food prep, carving wood, slicing cardboard, cutting plastic packaging, slicing rope etc.), which provides me with a little extra robustness in case I make a sloppy cut or bump into metal by accident. This still gives excellent cutting performance, though for a dedicated slicer like my Caly Jr ZDP189 I'd typically go only a few degrees more obtuse than the primary grind itself then apply a tiny microbevel at about 6 degrees per side.
These angles are much thinner than what nearly every other source I've ever come across recommends for knife sharpening.
*Shrug* They're durable enough for me, even for my fixed blades I baton with regularly, and I don't see any benefit to leaving the edge much thicker than it needs to be. I don't know what kinds of usage others have in mind when they recommend a 30 or 40 degree edge for a knife, but that is something I would consider too obtuse even for my axe, much less a small knife like the Calypso. The best way is to test it yourself, if you don't mind potentially damaging your knife. Think of the most edge abusive task you would typically expect to use the knife for, then start reprofiling your knife. When you're done, go try that cutting task. If the edge doesn't fail, go thinner. Keep going (gradually!) until the edge bends or microchips at the edge. Any damage detectable by the unaided eye or fingernail is what you should look for. Once you've found the point, you can sharpen a degree or two more obtuse than that, or you can go a degree or two more acute and use a microbevel. Either way, your edge should now be optimized for YOUR uses.
You can reprofile serrated knives too, with two options you can generally take. If you're patient, you can wrap the corner of a desk or sharpmaker rod with low grit sandpaper, and use edge trailing strokes at a more acute angle than you'd use to sharpen the secondary bevel. Or you can reprofile it like you would a plain edge knife, and stop once you're about to remove the secondary bevel completely. Then just sharpen it as you did before and regrind the back bevel as needed.
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[/CENTER]A Boker Trance with the serrated area reprofiled some. Very quick, rough job.
Specialty bladeshapes sometimes require a little ingenuity to reprofile. A standard hawkbill isn't very difficult. A SM rod or wooden dowel wrapped in low grit sandpaper will take care of it. Reverse S Curve blades and regular Recurves can be handled the same way.
This part can take anywhere from a few minutes if you're just dropping the secondary bevel angle of a flat ground 8Cr13MoV, to hours if you're regrinding a ZDP189 Endura flat to the stone (Not recommended, buy a belt sander :p ).
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[/CENTER]Paramilitary before and after reprofiling. The reprofiled blade sharpens quicker utilizing a microbevel, cuts with much less pounds of force and provides adequate durability for my needs.
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[/CENTER]Centofante 3 taken flat to the stone, turning the hollow saber grind into more of a flat saber grind. With a microbevel this could be used to carve seasoned hardwood, and was among the best cutters I've used.
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[/CENTER]A less extreme example, this Police 3 was reground slightly for better cutting and to even the edge bevels. Later it was ground to a thinner, more polished convexed edge and has performed much better.
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[/CENTER]Endura ZDP189 before and after being reprofiled. The factory edge came sharp enough to whittle the hair in the picture, but the penetration in thick materials when making a cut was very poor. The reground Endura cut very well and the edge was durable enough to stand up to batoning wood.
[CENTER]Bevel Refinement[/CENTER]
After grind the bevel in at the angle I want, and making sure the bevel is flat and the old one is completely gone, I begin to polish it. If I was using the XX course stone, I'll run the bevel over the X course a few times. Then I use the DMT fine stone. The big jump in grits doesn't matter much in my experience as the diamonds work quickly. Once the X coarse scratches are all gone, I'll either stop there or polish the bevel on 2000 grit sandpaper if I feel like making it really shine. At this point the edge should be polished and burr free, easily popping off arm hairs. This stage only takes a few minutes for pocket knives. Longer depending on the steel type and size of the knife.
At this point, with the edge at least shaving sharp and the bevel set, I use the knife to whittle seasoned hardwood rods I keep on hand. If the bevel is thin enough, the wood will easily peel off and the knife can be held nearly flat to the wood. To me this is more comfortable than having to turn the knife to cut using a 20 degree per side edge, which coupled with the reduced force the thin edge cuts with means much less strain on my hands and wrists. If I'm not happy with how it cuts, I grind it thinner. This part is subjective to a degree. You can try this or find some other way of determining how good the edge feels to you. Try to pick a cutting task that is affected more by geometry than sharpness though.
[CENTER]Sharpening The Edge[/CENTER]
For this I typically use the white sharpmaker rods. They provide a fine enough finish for an EDC in my opinion, but if I had an ultrafine benchstone I'd use that instead. I typically will hold the knife a degree or two higher than I ground the edge bevel at and use edge leading strokes. I've found they produce less burring than edge trailing. I use very few strokes, usually between 3 and 5 strokes per side on a freshly reground knife. I check the edge by making sure it effortlessly pops of hair stubble throughout the entire edge. From here I usually give it 5-10 strokes per side on a leather strop with green buffing compound, using edge trailing strokes. I check the edge and make sure it push cuts receipt paper with ease, and it is "sharp."
To touch up the edge, I repeat this section. Typically I touch up the edge when it no longer easily shaves, and for this I again use 3-5 strokes per side on the SM whites then a few strokes on my strop. The process of touching up an edge is easily completed in under a minute.
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