Convex Edge vs. Hollow ground

wildmanh

wildmanh

Part time Leather Bender/Sheath maker
Joined
Jul 9, 2000
Messages
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It looks to me like a lot of the new Khukuris are coming with a hollow ground edge instead of a Convex edge that they would normally have. My 25" AK came hollow ground.:confused: I prefer a Convex edge on most Khuks because its stronger IE less prone to impact or develope a wave after chopping hard stuff. The GS, Chit., and similer Khuks I like Hollow ground because they are IMO Slicers and that edge handles slicing better than Convex again, IMO.

This is why I like what I like. A few months ago I took some Khukuris out in the back yard to see which ones chopped through bone best. My 15" AK (Convex), 15" Sirupati (Convex) 16" GS (hollow ground), 12" AK (I think it was flat ground).

The 15" AK chopped up the spair ribs easily and did not show any signs of use. The 15" Sirupati took a little longer to chip but still no signs of damage to the edge. The GS took about as long as the Sirupati but develuped a small wave. And lastly, the 12" AK took a lot longer than the rest and it also developed a small wave. For me that show that a Convex edge is better for choppign threw harder substances (IE bone). On the other hand the GS sliced threw brush and saplings like a hot knife threw butter. Now, when I field tested my 25" AK (hollow ground) I chopped and split some rather hard wood and even hit a fence post and other metal a time or two. The edge developed a wave after chopping threw a knot in a log, impacted 1/8" from hitting the metal fence post and waved when it hit the other piece of metal (heared the sound but never found it, I think it was a nail).

In suming up, I would like to see a Convex edge on Choppers and Hollow ground on Slicers. So, what do the rest of you think? Convex or Hollow ground and on which Khukuris? Thanks for reading this,
 
I like the idea but I think we're probably going to be stuck with the edge the kamis give us using the "high tech" equipment they have at present.
 
I agree with Heber. My 25" AK is of the hollow ground edge too. I guess I will have to watch out for nails! Convex edge might be a little thougher here and would split wood better.
 
We need more high tech equipment -- belt sander and a drill press -- but where to get the belts for the sander?
 
The as forged scaly and rusty looking Chainpuri and Hanuman blades I ordered from Uncle Bill both have the edge bevels forged in.
Kumar somehow actually had what would normally be a flat edge bevel sort of forged into a concave or hollow ground shape.:confused:
I'm still not real sure of just how he managed that, but the kamis are definitely experts with both the forge and the hammer and anvil!!!!
When we first started getting khukuris from Shop-2, before it became BirGhorka, the edges were convex as a khukuri edge should be and IMO were forged to shape!!!!!!!
The conversion to the more hollow ground blades started kind of gradually, I think as the kamis learned to use the electrical
grinder.:(
Uncle Bill and I have talked about this quite a bit and the bottom line is that there haven't been enough failures to try to change the kamis mind's which is damned near impossible anyway.
(Damned kamis anyway, always trying to "improve" something!!!!)
I have to agree with Uncle Bill as he's the one who actually knows how many khukuris IF Any that have had to be replaced because of bent or chipped out edges.
The hollow grind does cut a lot freer up to its edge bevel and is usually sufficeient to carry through the cut.
The nice thing about convex edges such as those found on an axe is that they don't stick as badly in the wood.

H.I.Khukuris are still the worlds Best IMO and will beat the Cold Steel variety hands down unless they get to sticking in the wood as badly as the Cold Steel ones do.
And even then I would rather have a hand made khukuri from Nepal than anything made by Lynn Thompson and Associates.:p
 
I think what the kamis have found is it is much easier and faster to grind the edge than forge it and that's what they are doing.

But the current ground edge is holding up pretty well. I'm guessing we are getting maybe one returned edge (almost never a chip but bend or fold which can usually be repaired -- some very little damage and can be brought back to as new condition) in 5 or 6 hundred knives in the field which is not bad for the type use our khukuris put to.

Costs go up both here and in Nepal but the kamis are finding ways with the "high tech" equipment to speed up production and keep end costs pretty constant for which I'm thankful. I really would like to see them get a good belt grinder and I think a drill press would help, too, but they are doing a good and fast job with hand drills.
 
Thanks for all the good input, please keep it coming. I think it's increadable that the Kamis can forge a Convex or hollow ground edge. Even with a Hollow ground edge, my 25" AK hardly binds up in wood. Normally it just sails right through it.:D Looks like I'll have to purchase another Khukuri with a Hollow ground edge to see if it binds.:D

Me trying to explain another Khukuri purchase to my mom: "But mom, it's for a research project:D:p" Oh wait, I'm moving out soon so that won't be a problem any more. hehe hehe hehe:D:D
 
I'm wondering if the Kamis could use the "High Tech" equipment to put on a Convex edge. I am just starting to learn about grinding/pollishing but still, I think it would be possible. What do you guys think?

Uncle, if a Hollow ground edge does become the norm then I wouldn't mind paying a little extra for a Costom Khukuri that has a Convex edge. Of course I'll have to wait till I move out to order it.;)
 
I'm afraid to rock the boat right now but maybe later we can figure a way to get a belt sander into the shop. I've never tried to grind an edge on a forged blade but if I were going to try to get a convex edge I'd much rather tackle the job with a belt sander than a bench grinder. What the hell. Just stick it on a CNC Bridgeport, push go and be done with it.
 
It is going to be hard to work a convex edge with a grinder. You really need to use a slack belt. Although, they could compromise and put in a flat grind.

n2s
 
They have the slack belt -- a strip of leather like a strop with glue and grit on it. Problem is it will take a kami a couple of days to fashion the edge with this vs 10 minutes on the grinder.
 
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