Excellent article on convexing edge.

[firkin]

The site mentioned in this thread,

http://www.bladeforums.com/forums/showthread.php?s=&threadid=263199

which has a review of the Chiruwa AK by Singularity, also has a great illustrated article on convex edges:

"Convex Profiling and Sharpening by Hand HOW-TO"

http://outdoors.free.fr/s_article.php?id_article=66

Singularity used to post here a bit, but decided that for his technique and uses the lighter, straighter blades like goloks suited him better that khuks. He got a bit of static for that.

Too bad he doesn't post here anymore, but if you poke around that site, you'll find a lot of good information.

After reading his article, I see he's doing pretty much the same thing that I've done to a few kardas and some Scandinavian blades. Right now, I'm trying it on a 15" AK. The mousepad/sandpaper trick follows whatever profile the khuk has and gets the knife sharp. But if you want a full convex bevel, I think some serious stone-work is needed if one is working by hand.

You will dish out the stones, so be prepared for that. If the stones are hard, they just won't cut as fast. No need for spendy stones for the coarser grits. I use water on my stones.

Here's the progression of stones that I use:

*Cheap combo aluminum oxide stone (got mine from Ragnar, but I see that he has sold out of the larger size)
Coarse side
Fine side

*Blue "Oregon Stone" fine side
[This is softer than the other stone and seems to help a lot to take out the scratches from the earlier abrasives--dunno it is really a smaller grit or not. Maybe it just breaks down to a finer mud in use.--Does anybody know if these are still made and where to get them??]

*600 grit paper
[Sanding lenthwise with 600 grit paper will help you see if any deep scratches remain from coarser grits. use a piece of stiff, heavy leather for a sanding block. Go back to coarser stones if needed.]

*800 grit Japanese water stone
[Yes this will dish out, and it's not super cheap--dunno what else cuts this fast and yet doesn't leave deep scratches though--the "secret" to a smooth finish, IMO]

*600 grit paper again.
[This is very close to the water stone, you should be able to get a nice hand-rubbed finish if you haven't rushed through the abrasive sizes but it leaves more obvious fine scratches.]

Optional:

*800 grit Japanese water stone again.

*3000 grit water stone.
[Dang near polished--could go to finer paper next, or just strop the thing with green compound and use it like I do--pretty soon it will take a polish]

Two-sided 800/3000 grit waterstone are available, that's what mine is. Coarser Japanese water stones apparantly wear really fast, it's probably better to use something else like I do for the coarser grits if one is doing major reprofiling.

A couple recent threads on the shop forum have info on using water stones for profiling. (In that case the idea is to keep a crisp, sharp grindline on a flat-ground blade, whereas I'm convexing the bevel to remove any trace of a grindline )

 

[The Big Kahuna]

Thanks! Always learn a lot from this forum.

 

[firkin]

Oh yeah, a few more things...

1) If the khuk is sorta hollow-ground, like many are, especially in the recurve, the edge is automatically getting sharpened, even if most of the effort is concentrated elsewhere. Watch your fingers!

2) My aluminum oxide stone from Ragnar is 6x2x1, and it works best on the khuk if I lay the khuk on the edge of the counter and move the stone on the khuk. Remember 1)! It's not polished yet but the thing is about as sharp as one could wish any kitchen knife to be.

3)It's very close to being fully convex or at least flat everywhere now, once that happens, then using big bench stones to get a finer polish is much easier. And the finer stones won't wear as much. Trash the cheap coarse ones to save the spendy fine ones.

4) Some good safety points in this article from the same site:
http://outdoors.free.fr/s_article.php?id_article=94

This is the first time I've tried to reprofile the entire bevel on a khuk. (I've done a couple of JKM-1s, kardas and some other knives). And profiled 1/4 or 1/3 of a khuk's bevel on bench stones. Powering through the recurve as Fed suggested in some earlier posts works just fine, as long as one isn't overly concerned about wearing the corners of the stones. On the khuk, I've found that lengthwise sanding with 220 grit paper shows up where deep scratches remain and helps smooth things out a litte faster when using the coarse stones. When I use a piece of heavy leather as a sanding block, I fold it in half and wrap the sand paper around it, then apply the folded part to the blade. This keeps my fingers well clear and gives enough flex to work on any remaining hollows a bit. The thing is plenty sharp now, take off the wire edge and it is sharp indeed. The polish is needed for durability of the edge for chopping and the appearance and rust resistance of the rest. Just getting the edge aligned and straight increases the sharpness more than one (at leat me) might think. Again, watch the fingers!

Haven't cut myself yet on this project, which is good, because I'm kinda surprised at how much sharper the thing has gotten. And I could get it to shave and slice paper before if I stropped it.

Yeah, I guess a belt sander is added to the wish-list, but it looks like a few evenings will get me there too. Not quite ready to tackle my thin edged UBE yet, but after a couple more of the choppers, maybe.