"Tree felling" knives - can we make them better

[james terrio]

How about convex then hollow grind? Like axes grinds are made?

I don't see any particular advantage to that, but I haven't tried it. Full convex edges are durable, easy to maintain and even regrind... hollows and semi-hollows, not so much.

Fullers as shown in the pics and drawing above are interesting, and they certainly work to reduce weight while maintaining strength and rigidity. But they add a lot of expense (thicker stock to begin with and a lot more machining) to achieve the same mass and power one can get with thinner stock and a "normal" full flat or full-convex grind. Basically, a solution to a problem that doesn't exist... but they sure look cool.

 

[Insipid Moniker]

I think it's entirely possible to make a knife that is significantly better at chopping, but the concentration on one specific task will cost you versatility. Basically, your knife will look more and more like an axe and be worse and worse at slicing, carving and other tasks. Personally, I think some of the appeal of knives over axes or hatchets is that they can perform a wider variety of tasks. If you sacrifice that, why wouldn't you just carry a hatchet?

 

[John Moran]

Stress concentrators from the stamps, and leverage on the holes in the handle? really.

 

[McVeyMac]

I think it's entirely possible to make a knife that is significantly better at chopping, but the concentration on one specific task will cost you versatility. Basically, your knife will look more and more like an axe and be worse and worse at slicing, carving and other tasks. Personally, I think some of the appeal of knives over axes or hatchets is that they can perform a wider variety of tasks. If you sacrifice that, why wouldn't you just carry a hatchet?

Sometimes I do carry a small fixed blade and a hatchet. I have known several people who carried small hatchets hunting, field dressed and skinned deer with it and making wood for the fire was easier than with a typical small hunting knife. I see nothing wrong with this approach. However, I too think that a larger knife tends to have more versatility than an axe or a hatchet if you are only carrying one tool.

 

[Insipid Moniker]

Sometimes I do carry a small fixed blade and a hatchet. I have known several people who carried small hatchets hunting, field dressed and skinned deer with it and making wood for the fire was easier than with a typical small hunting knife. I see nothing wrong with this approach. However, I too think that a larger knife tends to have more versatility than an axe or a hatchet if you are only carrying one tool.

That's sort of what I'm getting at. I actually carry a knife, saw and hatchet (or machete) if I'm expecting to do a lot of wood processing, but I can understand the argument that a large knife gives you much of the function of that combo with a single tool. But if you start specializing that tool for chopping you get back to the point where I'm going to be carrying a specialized chopping tool and still have to bring another knife for general use tasks. If that's the case, why not just go with a time-proven chopping tool that's inexpensive and available at any big box store?

 

[Blackie Scantling]

Sometimes I do carry a small fixed blade and a hatchet. I have known several people who carried small hatchets hunting, field dressed and skinned deer with it and making wood for the fire was easier than with a typical small hunting knife. I see nothing wrong with this approach. However, I too think that a larger knife tends to have more versatility than an axe or a hatchet if you are only carrying one tool.

It was to much of a load to carry a pocket knife?

I have a dbl bit Kelly cruiser weight ax that I got so sharp it would shave and slice paper and no doubt would have skinned and butchered a deer. First time I used it to cut 1" green mesquite for a barbecue smoker it chipped chunks off the edge and rolled other areas.
I realized I could either shave and skin deer with a 2lb. ax or use it for what it was intended for and that was to chop wood. But I couldn't do both.

 

[idaho]

Stress concentrators from the stamps, and leverage on the holes in the handle? really.

Stamps - multiple broken bk&t, multiple broken ontario rats on the serrations,
Handle - multiple broken 1095 and stainless fulltang blades on the first hole.

 

[marthinus]

I am still waiting to see someone use a knife in a lumberjack competition.....

[video=youtube;LRjPwWxgF-E]http://www.youtube.com/watch?v=LRjPwWxgF-E&list=PLMno7j0UW8QDkZb2XGnouSmM7QYhY7slj&feature=player_detailpage#t=220[/video]

IMO there is a reason why an axe is still the right tool for tree felling.

 

[idaho]

I am still waiting to see someone use a knife in a lumberjack competition.....

[video=youtube;LRjPwWxgF-E]http://www.youtube.com/watch?v=LRjPwWxgF-E&list=PLMno7j0UW8QDkZb2XGnouSmM7QYhY7slj&feature=player_detailpage#t=220[/video]

IMO there is a reason why an axe is still the right tool for tree felling.

Ofcourse axe it many levels of magnitude better than a knife.
Yet, there is still market for 10 inch knives, and woodworking is their prime use (at least in YT videos )

 

[HwangJino]

What's wrong with a hatchet and small mora?

 

[james terrio]

Stress concentrators from the stamps, and leverage on the holes in the handle? really.

Yeah, there are lots of examples of those kinds of failures. It doesn't happen every time, of course, but it does happen... and that can be unsafe, and definitely inconvenient and expensive for the person using the knife.

Stamps - multiple broken bk&t, multiple broken ontario rats on the serrations,
Handle - multiple broken 1095 and stainless fulltang blades on the first hole.

These concerns are all valid. Stress risers are always a bad idea, and they really show up on big knives that see heavy chopping. BK&T has switched over to laser-etched logos instead of stamped ones, precisely because of breakage problems (which were rare, but still catastrophic and disturbing). Serrations (IMO) have no place on a chopping knife, because they add little to no usefulness and can cause problems. As for holes in the tang, they must also be designed in such a way that they do not concentrate stress right near the ricasso area. Very few major manufacturers bother to chamfer the holes in the tang; that alone would help.

What's wrong with a hatchet and small mora?

Nothing. What's wrong with staying on topic and discussing chopping knives? Like it or not, they're here to stay and thousands of people enjoy using them. If you don't, that's fine... there are lots of threads and even entire forums dedicated to using hatchets and small knives.

I honestly feel sorry for the people who start chopper threads with honest intentions, and intelligent questions - as it seems idaho did. They nearly always turn into a "you should just carry an axe or chainsaw" thread within the first page or two, as we've already seen here. Then they escalate into namecalling and arguments and the mods have to close them. Let's break that cycle, shall we?

 

[leghog]

To see if I could do it

Waste of a tree.

 

[numbersman]

Would you believe - smatchet?

 

[idaho]

Yeah, there are lots of examples of those kinds of failures. It doesn't happen every time, of course, but it does happen... and that can be unsafe, and definitely inconvenient and expensive for the person using the knife.

i believe that this is the best way to make large knife handle tang. Single mounting point, at the far side of handle. And stress absorbing handle material - unfortunatly, molded handles are next to undoable at custom/handmade scale, so single block of micarta will have to suffice

But those knives (scrapyards) have unnesesary choils, and maybe their grinds can be better.

These concerns are all valid. Stress risers are always a bad idea, and they really show up on big knives that see heavy chopping. BK&T has switched over to laser-etched logos instead of stamped ones, precisely because of breakage problems (which were rare, but still catastrophic and disturbing). Serrations (IMO) have no place on a chopping knife, because they add little to no usefulness and can cause problems. As for holes in the tang, they must also be designed in such a way that they do not concentrate stress right near the ricasso area. Very few major manufacturers bother to chamfer the holes in the tang; that alone would help.



Nothing. What's wrong with staying on topic and discussing chopping knives? Like it or not, they're here to stay and thousands of people enjoy using them. If you don't, that's fine. We're not offended by that

I honestly feel sorry for the people who start these threads with honest intentions, and intelligent questions - as it seems idaho did. They nearly always turn into a "you should just carry an axe or chainsaw" thread within the first page or two, as we've already seen here. Then they escalate into namecalling and arguments and the mods have to close them. Let's break that cycle, shall we?

Nah, after years and years of internet use I've learned to ignore such post, and try to steer topics in the direction I am interested in by adding more content in the main topic.

 

[james terrio]

i believe that this is the best way to make large knife handle tang. Single mounting point, at the far side of handle. And stress absorbing handle material - unfortunatly, molded handles are next to undoable at custom/handmade scale, so single block of micarta will have to suffice.

Stout narrow tangs like that one definitely have their place, and can work very well. As for softer handle materials, one way to deal with that (without farming out to an injection-molding company, which as you say is prohibitively expensive on a small scale) is to use "washers" made of neoprene, horse-stall mat material etc, and stack them up on the tang, to build the handle like the classic leather handles. The handle will then require a solid (micarta, G10, steel or whatever) pommel, which can be secured through a single hole at the end, as in that picture.

Nah, after years and years of internet use I've learned to ignore such post, and try to steer topics in the direction I am interested in by adding more content in the main topic.

Right on :thumbup:

 

[firebolt]

i have been making my own blade sports knife and competing with it ,
big learning curve, grinds full flat , blade will stick to easy other wise , for competition, grind out as thin so it would not chip, so find the limit off the blade steel and heat treatment and make it a hair thicker
being in the woods, anything thinner as my upper arm, i use a knife ( or saw depending on the use off harvested wood and preservation off the tree )
is the best you can have, makes quick work, wrist thick usually one blow even with a cheap ass cold steel kukri ( i did some grinding on it ) for the relative thin stuff it works even better than a axe.
bigger than that, i will gladly take a felling or small axe any day over a knife , sure it can be done with a knife , but to get a work out i like to do outer things

 

[Myal]

I have a bigger knife i use to cut trees down , to baton , to pry with and generally have fun
Its not that thick , and yeah its a high carbon steel , its got some distal taper goin on , the tang is tapered , the blade is tapered , its convex ground , and its a fairly low Rc hardness , guessing at mid to low 50s .
I gave it a hand and a half width for the handle , I can swing it two hands all day , no issue , no hotspots , but it excels at light brush / machete use one handed .
pretty much just a sharpened up recycled leafspring from under a 69 ford :

I built it to fit me , for harvesting canegrasses for livestock .

Using it for tree cutting , I can put some slice into the cut or chop , instead of counting purely on impact alone to force the edge into the wood . That means wrist sized green wood is sliced in one swing usually .

This knife is kept shaving sharp , it holds its edge surprisingly well under a lot of abuse too . I gave it a profile that will slice a roast or tear up an iorn bark rail sleeper and not worry about it

 

[John Moran]

q max = q(1+2a/b) = q(1+2 x sqrt a/p)
where ρ is the radius of curvature of the crack tip. A stress concentration factor is the ratio of the highest stress (q max) to a reference stress (q) of the gross cross-section. As the radius of curvature approaches zero, the maximum stress approaches infinity. Note that the stress concentration factor is a function of the geometry of a crack, and not of its size. These factors can be found in typical engineering reference materials to predict the stresses that could otherwise not be analyzed using strength of materials approaches. This is not to be confused with 'Stress Intensity Factor'

Idaho
"Some failures have occurred" is not a data point in a process for eliminating failure, it is a true statement about everything man made. My suggestion is to take your 5 areas of failure and assign a value of 1 to 100 for each based on empirical data, and evaluate the design considerations for areas of acceptance and compromise. For areas where you can't find empirical data there are literally billions of broken parts in the world from which reference material has been generated to assist in your undertaking. ( The above formula is just one small example).

Good luck in your design.

 

[mete]

I had a book [until I lent it out ] about the Burma campaign in WWII written by someone who was there ! A whole chapter was devoted to knives and they carried various types plus an axe .An excellent discussion and they weren't just making a video, they were serious !! So test your knives in the real world !