Simple way to put a convex edge on a CAK?

Anything made of suitable metal can be made sharp enough to shave. My 15" 1/2" thick Ang Khola, 18" 1/2" thick Bhojpuri and 18" 7/16" thick M-43 can all shave hair off my legs... hell, even my camp ax (which I don't use anymore) could shave

You can set up a cheap convex sharpener by tacking or taping sandpaper to a mousepad and putting that on a flat surface. The only thing you'll probably need to pay for in this setup is the sandpaper: a 3M assorted wet/dry pack ( sheets of 220, 400, 800, 1000 grits) only costs $5ish. Sharpen the blade at roughly 18ish degrees per side without adding too much pressure onto the blade - the give of the mousepad will convex the edge with a ~21ish degree final angle. Do all the work (this means creating a bur) with 220 grit - only use the higher papers to refine/polish the edge you establish. Once you finish with the 1000 grit, use an old leather belt to strop the bur off - be sure to keep the belt taught and to use minimal pressure!

For the basic technique using the above method, check out this video. Remember he's only refining the convex edge - not establishing one. The technique is the same though, you just need to start at 220 and remember not to move on to higher grits until you can feel the bur you've created using 220! If you move on too early, you'll just find yourself with a dull (albeit shiny) edge!


You can see my setup in the background of this picture - I'm too lazy to snap another one:


Here's the end result of your efforts - My m43 can shave with ease and still hit a tree full force without any visible edge damage:

 

Excellent video tutorial on how to put a convex edge on a knife here http://www.knivesshipfree.com/pages/Sharpening-Videos

With that said, I only convex my tomahawks and use my Spyderco Sharpmaker to sharpen my khuks. I have also found that a medium mill bastard file goes a long way and saves considerable time in getting the edge thinned out enough to let the Sharpmaker really do it's job well. With many of my khukuris, the edge thickness/sharpness varied a bit from tip to cho and taking a file to the thick spots allowed me to even the edges out and then get them shaving sharp along the entire edge with the Sharpmaker.

 

Once sharpened and often in use use the chakma, it works the same as a stell without removing metal. They really help preserve the edge under heavy use.

 

Or to straighten out dings/rolls in the edge if you do something stupid like drop your M-43 tip down in the grass, but it hits an unseen rock.

 

Well as the old fisherman said, I must not be holding my mouth right. I've been researching the benefits of a convex edge and it does sound stronger than a flat edge. To be honest I didn't even know about convex edges a month ago and didn't realize when i first tried to resharpen my 15' AK that the reason it was so difficult and time consuming was because I was actually reshaping the edge from a convex to a flat. But back to what I first said. I've been watching the videos, bought the sandpaper, adjusted my pressure to about what I use when i'm shaving and after using the 220 grit to reshape my edge back to convex on a small off brand, carbon steel khukuri I picked up awhile back I still can't get it sharp enough to peel potatoes. I do have a couple of butchers steels, one course and one I've had and been using for 20 yrs that is now a fine. So I just reshaped my edge back to flat on the cheap kuk and shaved some armhair. I'm gonna make a good strop and order some compound, but I may need to check out the method involving power tools as I have a belt sander. I might have better luck with that. Oh, I did have one other thought. Does anyone know what the traditional nepal method for maintaining a shaving edge on a Khukuri is. Do they just use a chakma?

 

It's really only OCD people like me who put literal shaving sharp edges onto kukris... a kukri is a chopper, and a chopper doesn't need to be able to shave to perform it's intended task well. In fact, a shaving edge probably wouldn't stay shaving sharp for long when you do heavy chopping tasks - I know I occasionally have to run my kukris over 2000grit then strop them to remove the microscopic burs that destroy the shaving convex edge. They still chop as well when these invisible burs form, but the microscopic burs do ruin it's ability to shave.

You would never see a Nepalese farmer putting a shaving edge on their kukri as maintaining the edge past functionality is a waste of time - I grew up in rural Philippines and I know for a fact that farmers didn't do it with their bolos (which, due to being more machete-like in usage, would actually benefit more from such an edge than a kukri would). I'm assuming that the Nepalese farmers do it the same way people did it in the Philippines: a simple coarse/fine stone then actual field usage to knock the bur off - perhaps a farmer or two would have something to steel the bolo in case it deforms.

 

Great advice all around... and if I may add some advice for folk uncertain about sharpening, err on the side of acuteness. It's a lot less hassle to have to go back and decrease the sharpness of a thin edge than to thin down an obtuse one!

 

Thanks killa. Thats helpful information. I'll prolly just keep steeling my kuks. I never use stones anyway for any of my knives. Just my fine steel for bringing up an edge to shaving sharp and my coarse for a really dull knife when i need to remove alot of metal followed by my fine steel with a light touch. I was interested in the convex techniques but I guess in the long run I'll stick to what I'm familair with. Steeling also is, for me, easier to sharpen an edge with a deep belly like kuks have than if I used a stone. Plus I like having it shaving sharp in case, you know, I have to skin out a buffalo, elk or grizzly.

 

No. It is a way to go with a khuk, and while some of us are quite enthusiastic about it, don't let yourself be unduly swayed by that. The average farmer in Nepal does not own a belt sander. The Ghurkas most likely do not pack mouse pads and sandpaper when they deploy. They've all managed to get by for centuries, regardless.

If you want to get into convex edges, Killa offered the best option for someone on a strict budget. It does work; I initially learned to do it the same way. His advice regarding the level of sharpness necessary to do the job is also spot-on. Sharper is always better, but the law of diminishing returns applies here. A mirror-polished shaving edge will not chop wood appreciably better than the standard HI edge in my experience. That having been said, a high level of sharpness can be helpful when clearing lighter vegetation.