I am just wondering how you guys sharpen these big boys, I am not interested in esoteric techniques like sharpening on yak wheels, but just good old sharpening.
Do you use a stone or a spyderco type sharpener, some of these thinhs look like you would move the stone over the blade and not the blade on the stone...
Just wondering what works?
I'll give this a go:
I start with a coarse DMT diamond file (basically a "stone on a stick," more file than stone in use) and work my way up to the medium cut. I very rarely use the fine cut on the big knives, it's just not appropriate in my view. The edge should be relatively rough if you want to take down hard woods or clear tough, woody-rooted plants where grit and sand are likely to contact the edge. Anything but a coarse or medium cut edge will just dull pre-maturely in hard use. I'm trying to leave some "tooth" in the edge with my technique for hard use field knives and this seems to work out quite well. It's also easier to maintain. Shaving with a Khukuri, however temping, is generally not recommended. Buy a decent straight razor if you like going old-school on your mug and leave the chopping and slashing to the khuks.
The first convex edge bevel I cut is around 10 degrees. I usually work my way down to a less acute 35 degree final angle after radiasing from 10ish-to around 35 degrees in increments of about 5-8 degrees each (the angle varies by blade, thickness of the blade towards the edge, etc). I'll smooth the radii of each edge bevel until I've cut and partially polished down to the last bevel of the edge.
This method for getting a "rolled edge" is about a one to two hour job with diamond stones, 5-7 with a good set of files on a new blade. It's only about 20 min to touch up a heavily dinged and dulled edge with the same diamond files and maybe 3-5 minutes with these same tools after moderate dulling. Diamond stones/files are pretty aggressive and eat through a lot of metal, not something you want to do any more than you have to. A coarse butchers steel can re-align the teeth and repair minor dings/chips with limited metal removal (it's a glorified file with a less aggressive cut). I recommended having a coarse butcher steel for touch-ups in the pack/pouch for just such occasions. Smaller steels can even fit in the Khukuri shealth as an alternative to the Chakmak.
To get a clean convex profile, most of my edges are about 1/2" inch wide. The profile takes some practice to get consistent on both sides and notch to point. The bigger the knife, the greater the risk of cutting asymmetric convexed radii on each side, or uneven along the entire bevel. I've ruined my share of edges and even whole blades getting the technique down.
Since there is no replacement for practice, it's my advise to buy one of those $12 Khukuri's that have aweful blades and unhardened edges. You'll probably get the technique down in the process of destroying your first or second "practice" blade. eBay is a great source for some total garbage knives, I suggest starting there (a cheap Khukuri is best since the angles will be similar, but it's not absolutely essential).
Regular files are rarely hard enough to eat much steel on a good knife, but if you get particularly hard set of files, the slower cut might actually be a good thing as you'll have time to react if you start taking too much metal off of one side. Best to start with a good set of files before going to the more aggressive diamond impregnated sticks/wands/stones/files. A "good" set of files might put you back $25.00 (they need not be very large, the 8" and 10" type are both great).
Work an inch at a time and smooth the whole edge every few minutes of sharpening by giving the entire edge a light burnishing (slide the file diagnally across the edge from the nose to the heel, same direction each side) before going back to the next section on the edge to be addressed. The point of the blade is the most difficult to sharpen, since it's unsupported in most safe holding positions and you have to apply some pressure to remove metal. You can brace the blade with one foot while using both hands to steer and push the files, but it's not terribly safe and I wouldn't recommend it. A safer method (though not necessarily "safe") is to put the knife on some shop towels on a shop bench, press down hard with one hand to control the blade with just the point of the blade protruding over the edge of the table and work the edge on the point slowly and carefully. Invest in a pair of cut resistent gloves (kevlar, aramid, heavy leather gloves are the least protective of these) to do this or any other type of sharpening of a big blade, you'll thank me later.
I usually start cutting my convex edges at the point (contrary to some advise to begin at the heel, probably good advise for shorter, straighter blades) so that I can more safely wrap the blade in a heavy cut resistant material and move this back from the point a bit at a time as I work the edge with the diamond files. I came up with the additional safety procedure after an incident involving a moment's distraction. Nuff said.
Everyone has a different technique, but files of various types, particularly half-rounds, rounds and narrow flats in rough cut, medium cut and medium-fine cut are just about ideal for these curved rough use blades. I can go through quite a lot wood, bone and other hard materilas with these convex "rolled" edge profiles, but your mileage may vary.
Be safe and good luck.
For me, if I really want to do it "right" and the edge is pretty blah from the get go, I rough out a convex edge with a couple of stones, move on to sand paper, and strop on leather. I can get an edge that is hair popping sharp all the way down the edge this way. It typically takes me 4 or 5 hours, but it's worth it.
