What Is A "Doubly Convexed Balde"?

In a video on the Ka-Bar site, Ethan Becker states that the original Kephart knife had a "doubly conveyed blade" (see video 1:58). Does he mean that it's a convex with a micro bevel?

Thanks. :)



P.S. I can provide a link to the video, but I'm new here, and I don't want to violate any forum rules.
 

Chris Railey

KNIFE MAKER
My Guess: Historically, knives were thinner during the period. Also, Kephart liked a slicey knife. YouTube knife maker William Collins is similar in this regard.
Its hard to get more slicey than a thin full flat grind. Not arguing, just making conversation. Plus, with a convex spine it would be hard to use a fire steel with it. I guess its just a change in time.
 
Its hard to get more slicey than a thin full flat grind. Not arguing, just making conversation. Plus, with a convex spine it would be hard to use a fire steel with it. I guess its just a change in time.

I'm not an expert. Really, really not. :) Your point about the full flat grind makes sense to me. But did they have fire steels in the late 1890s? Also, I thought the video said that Kephart even tapered the tang, which, if it means anything, might mean that they just liked the feeling of a thin, quick-handling knife. Still guessing here.
 

tkroenlein

Well-Known Member
Other than balance or reduction in weight, what is the benefit of that?
IDK. The sloppy flat grinds on the Condor Kepharts are kinda the same.

I'm not sure a knife moves through flesh fast enough to benefit from reducing drag, but it might help a tater not stick?
 

Jon Buescher

Well-Known Member
I'm not an expert. Really, really not. :) Your point about the full flat grind makes sense to me. But did they have fire steels in the late 1890s? Also, I thought the video said that Kephart even tapered the tang, which, if it means anything, might mean that they just liked the feeling of a thin, quick-handling knife. Still guessing here.
they definitely had flint and steel, not sure if Ferro Rods were a thing, I guess I could look it up but...
 

Smallshop

KNIFE MAKER
I convex all my blades now. The apex of the blade being at the top of the spine...the only time I "doubly convex" is when the belt is too slack or I hold the blade incorrectly on the grinder.(I call it a mistake) It does not take much of a convex radius to get the benefit of a convex shape. I only grind the complete convex because it is easier to keep the two sides more accurate. Honestly...I think 1/8" convex is adequate. But...a full convex looks sweet!

I cannot really see any advantage to "doubly convex" it seems akin to guys that hollow grind with the bottom of the blade (cutting edge) being thicker than the thinnest part of the hollow...other than weight reduction it adds nothing to performance. A convex is already moving whatever you are slicing away from the blade because of the wedge effect...and again the first 1/8 of the blade seems to do that. dropping the apex essentialy means changing the radius of the convex to a steeper cutting angle....which I try not to do with my thick blades. You want to be careful to not re-invent the axe...lol!

my 1/4 thick bowie blades seem to slice in the kitchen rather well....never would have guessed. But they do not seem to vacuum food to the sides...
 

Chris Railey

KNIFE MAKER
I'm not an expert. Really, really not. :) Your point about the full flat grind makes sense to me. But did they have fire steels in the late 1890s? Also, I thought the video said that Kephart even tapered the tang, which, if it means anything, might mean that they just liked the feeling of a thin, quick-handling knife. Still guessing here.
Tapering the tang really does help the balance of a knife, that is how I set the balance point of any knife I make 1/8" or thicker. I guess it had more to do with weight and personal preference perhaps. I have made a couple of Kephart style knives but they were full flat grinds. I guess I should have done more research. The new owners did not seem to mind though.
 

Smallshop

KNIFE MAKER
Tapering the tang really does help the balance of a knife......
Within reason of course. I notice almost every custom bowie seems to have a distal taper which is opposite of what it needs. Taking a nose heavy knife and making it even more nose heavy seems counter intuitive to me. I think guys get a pass on this 'cause we all expect a long blade to be nose heavy. I got my short Bowie to balance right at the guard but it took two fairly deep fullers (on each side) to do it....it feels very quick for a larger knife...

I believe distal tapers have become a "sign" of good craftsmanship even when not warranted. Of course I am biased 'cause I do not really care for 'em....lol.

On a short knife I cut out the tang area and on a long knife add fullers...I guess we all do what we think looks best...lol.
 

Chris Railey

KNIFE MAKER
Yeah I do not taper all of my tangs. I guess my post above does read that way. My reason is for balance only. If a blade is tip heavy I use heavier handle material or maybe a pommel to move the balance point where I want it. In that case tapering the tang would be counterproductive for sure.
 
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