design feature toughness

[NickWheeler]

I make my plunges sharp. Not 90 degree inside corners sharp, but like a 3/32" or so radius... And I have never had a blade fail at the plunge.

 

[james terrio]

I make my plunges sharp. Not 90 degree inside corners sharp, but like a 3/32" or so radius... And I have never had a blade fail at the plunge.

It's true that even a small radius like that helps a great deal. :thumbup: The same goes for the transition between the shoulders and tang of a narrow-tang knife. It's simply a matter of distributing stress, in kind of the same way that an arched doorway is stronger than a rectangular one.

In my former life in the printing/converting industry, I used hundreds of solid rotary dies and cylinders like this:

I never saw one break that had even a very small radius between the body and the "shafts" on each end that fit into the bearing blocks. I saw several of 'em break that had 90degree inside corners there. Believe me, blowing up a $2K piece of tooling and putting a $30K job on hold while you wait for a new one to come in gets people all kinds of irritated. Point is, it doesn't take as much pressure as you might think to snap off a 2" diameter chunk of hardened tool steel if all the stress is focused on that one tiny, tiny area.

 

[chad2]

I make my plunges sharp. Not 90 degree inside corners sharp, but like a 3/32" or so radius... And I have never had a blade fail at the plunge.

i hope that people dont think that i am trying to bash on knives that have plung grinds because i am not, my purpose for this thread is to find a way to push the limits of the steel with out having any issues with the design. i want to make a knife that if it fails it will be because the material cant take it any more not because of a thumb ramp or jimping or plung grind.

 

[chad2]

James nailed it when he mentioned "compromise". If I want to build tough, I compromise cutting and slicing ability. Finding that sweet spot is the key. I have a model that has a 5" handle with a 6" blade. It is close to .300" thick at the spine. It will never win any cutting competitions and will probably destroy a perfectly good sushi roll... but it fits my ideal of a "survival" knife perfectly(for the moment). I named it the PIG... Purposefully Inflated Geometry.

Hey rick that sounds awesome! Also what kind of resin do you coat your wrapped handles in? And does it stay flexable after cured?

 

[Buffalohump]

I think Scott Gossman already made your knife.

This one has an 8 inch blade of 3/16 A2. Full tang, thick all the way to the tip. Convex edge. No weak points here!